European Journal of Endocrinology (2006) 154 763–775 ISSN 0804-4643

INVITED REVIEW Insulin-sensitizing agents in polycystic ovary syndrome Renato Pasquali and Alessandra Gambineri Unite´ Operativa di Endocrinologia, Dipartimento di Medicina Interna, Universita` Alma Mater Studiorum, Azienda Policlinico S. Orsola-Malpighi, Via Massarenti 9, 40138 Bologna, Italy (Correspondence should be addressed to R Pasquali; Email: [email protected])

Abstract Insulin-sensitizing agents have been recently proposed as the therapy of choice for polycystic ovary syndrome (PCOS), since insulin resistance and associated hyperinsulinemia are recognized as important pathogenetic factors of the syndrome. Moreover, since almost all obese PCOS women and more than half of those of normal weight are insulin resistant, and therefore present some degree of hyperinsulinemia, the use of insulin sensitizers should be suggested in most patients with PCOS. Insulin sensitizer treatment has been associated with a reduction in serum androgen levels and gonadotropins, and with an improvement in serum lipids and in prothrombotic factor plasminogen- activator inhibitor type 1, whatever the insulin sensitizer used. This therapy has also been associated with a decrease in hirsutism and acne, and with a regulation of menses and an improvement of ovulation and fertility. Notable improvements in all these parameters have also been described after a change in lifestyle approach, particularly in the presence of obesity. Lifestyle interventions should therefore be combined with insulin sensitizers in PCOS when obesity is present.

European Journal of Endocrinology 154 763–775

Introduction hyperandrogenism in the majority of PCOS women, particularly when obesity is present (5, 6). On the other Polycystic ovary syndrome (PCOS), one of the most hand, obesity by itself may favor ovarian hyperandro- common causes of ovulatory infertility, affects 4–7% of genism in a subset of PCOS women, by mechanisms that women (1). Since the first description by Stein and may be partly independent of the primary role of excess Leventhal in 1935 (2), this syndrome has, over the years, circulating insulin (7, 8), provided that genetic or other been defined in different ways. In 1990 the National still undefined factors are present (9). In most PCOS Institutes of Health (NIH) established new diagnostic patients, however, obesity probably represents a second- criteria for this disorder, which were based on the ary additional pathogenetic condition, capably of presence of hyperandrogenism and chronic oligo- amplifying primary factors leading to exaggerated anovulation, with the exclusion of other causes of ovarian androgen secretion, such as an increased hyperandrogenism such as adult-onset congenital luteinizing hormone (LH) stimulation (5, 7, 10). adrenal hyperplasia, hyperprolactinemia, and andro- Regardless of the causative factors, there is no doubt gen-secreting neoplasms (3). More recently, a consensus that the phenotype of a woman affected by PCOS is conference held in Rotterdam in 2003 re-examined the fundamentally related to two main factors, namely the 1990 criteria and agreed to the appropriateness of hyperandrogenic and the insulin-resistant hyperinsuli- including ultrasound morphology of the ovaries as a nemic states (Fig. 1). further potential criteria to define PCOS (4). On the other Treatment of androgen excess can be pursued by hand, it was also established that at least two of the reducing androgen production rates from the ovaries following criteria are sufficient for diagnosis: oligo and/or and the adrenals or, conversely, by counteracting anovulation, clinical and/or biochemical signs of androgen function at receptor levels. An alternative is hyperandrogenism and polycystic ovaries at ultrasound. represented by therapeutic procedures aimed at improv- Despite this effort, however, the definition still appears to ing insulin resistance and, consequently, hyperinsuli- be incomplete, since it does not consider characteristics nemia. As reported above, this method exploits the frequently present in PCOS, particularly insulin resist- pathophysiological role of excess insulin in determining ance, hyperinsulinemia and obesity, the key features of increased androgen secretion and activity. The improve- the metabolic syndrome (5). Insulin resistance and ment of insulin resistance and the decrease of insulin associated hyperinsulinemia are also now recognized concentration and action can be achieved in different as important pathogenetic factors in determining ways: (i) by reducing body weight with lifestyle

q 2006 Society of the European Journal of Endocrinology DOI: 10.1530/eje.1.02156 Online version via www.eje-online.org

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Figure 1 Pathophysiological role of hyperan- drogenism and the insulin resistance-hyper- insulinemic state in determining the PCOS phenotype. modifications, if overweight or if obesity is present; (ii) whilst it is uncommon in their normal-weight counter- by using insulin-sensitizing agents; (iii) by using parts (5, 12). In any case, the prevalence rate for antiandrogens. It has in fact been demonstrated that impaired glucose tolerance in the population of obese long-term treatment with antiandrogens may improve PCOS subjects appears to be higher than that reported insulin sensitivity in both normal weight and obese in population-based studies on the incidence of glucose PCOS women presenting an insulin-resistant state (6). intolerance in women of similar ages (13), although In addition, there is increasing evidence that ovulation epidemiological studies are lacking. These findings and fertility rate can also be significantly improved by indicate that obesity may contribute to determining insulin sensitizers, often regardless of changes in the insulin-resistant state and may impair glucose circulating insulin levels. This opens up the intriguing tolerance in PCOS. Although insulin resistance seems possibility that these compounds can exert a direct to play a determining role in the development of action at ovarian level, and introduces new routes in the diabetes, the presence of insulin resistance does not treatment of infertility in PCOS. immediately imply a concomitant alteration of glucose This short review is focused on the role of insulin tolerance. In fact, most obese insulin-resistant PCOS sensitizers, given alone or combined with other women still have normal glucose tolerance. However, it therapies, on hyperandrogenism, metabolism, body has recently been found that PCOS women with composition, menses abnormalities and spontaneous impaired glucose tolerance or type 2 diabetes are and stimulated ovulation in PCOS. significantly more insulin resistant and hyperinsuline- mic than those with normal glucose tolerance, regardless of the presence of obesity (11). It has also PCOS, obesity, insulin resistance and the been reported that the development of states of glucose metabolic syndrome intolerance can be predicted to a certain extent, since there are early markers such as low birth weight and This metabolic syndrome is a consistent feature of the early menarche age in PCOS, as in the general majority of obese women with PCOS, although it can population (14, 15). Prospective studies in which also be detected in many normal-weight affected women PCOS women were followed for approximately 10 (5, 6). Obese women with PCOS, particularly those with years have also found that insulin resistance tends to the abdominal obesity phenotype, are usually more worsen over time, together with an increment of insulin insulin resistant and more hyperinsulinemic than and c-peptide response to an oral glucose challenge, and their normal-weight counterparts (5, 7). Both fasting that, in several cases, glucose intolerance appears (16). and glucose-stimulated insulin concentrations are in Taken together, these findings strongly support the role fact significantly higher in obese than in non-obese of insulin resistance in the development of altered PCOS subgroups. Accordingly, studies examining insu- glucose tolerance states in PCOS women. lin sensitivity by using different methods, such as the Studies examining the extent of insulin secretion in euglycemic hyperinsulinemic clamp technique, the relation to insulin sensitivity have demonstrated that a frequent-sample intravenous glucose test and the insulin b-cell dysfunction may coexist with insulin resistance in test have further demonstrated that obese PCOS women obese PCOS women. In particular, a defective early have significantly lower insulin sensitivity than their phase b-cell insulin secretion and a reduced insulin non-obese PCOS counterparts and, therefore, a more secretory response to boluses or graded intravenous severe insulin-resistant state (see extensive reviews in infusion of glucose, when expressed in relation to the refs 5, 7, 8). degree of insulin resistance, have been reported in these Glucose intolerance is present in as many as 30–40% women (16, 17). Notably, these findings have been of obese PCOS women in the United States (5) and described in Hispanic-American insulin-resistant obese probably to a lower extent in those living in Europe (11), PCOS women, but not in PCOS women living in Europe

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Downloaded from Bioscientifica.com at 09/30/2021 12:05:43PM via free access EUROPEAN JOURNAL OF ENDOCRINOLOGY (2006) 154 Insulin-sensitizing agents in PCOS 765 or in Mediterranean areas (11, 18). It is therefore without the metabolic syndrome. Taken together, possible that several environmental factors, such as these findings demonstrate that the prevalence of the habitual diet or other lifestyle behavior, may be involved metabolic syndrome in women with PCOS is higher in this difference. than that of the general population, regardless of PCOS women, particularly if they are obese, may also ethnicity and geographical area. They also indicate a present with a more atherogenic lipoprotein pattern strong association between the metabolic syndrome and profile, which is characteristic of the metabolic the hyperandrogenic state. syndrome and is strongly associated with the presence Studies in American (23, 24), Asian (25) and Italian of insulin resistance. A greater reduction of high density (11) subjects have also shown that women with PCOS lipoprotein (HDL)-cholesterol, together with a higher have an increased risk for the selective development of increase in both triglycerides and total- and low density impaired glucose tolerance and type 2 diabetes, with a lipoprotein (LDL)-cholesterol levels, has in fact been tendency to early development of glucose intolerance observed in obese women in relation to normal-weight states (16), when compared to the general population. PCOS women, particularly when the abdominal obesity The close connection between PCOS and glucose phenotype is present (8). intolerance is further emphasized by the finding of a Some recent studies have used the ATPIII criteria to high prevalence of polycystic ovarian morphology on assess the prevalence of the metabolic syndrome in ultrasound scans in both premenopausal women with PCOS women. Glueck et al. (19) studied 138 PCOS type 2 diabetes (26) and in those with previous patients and found a prevalence rate of 46%, whereas, gestational diabetes (27). Similar to what occurs in more recently, Apridonidze et al. (20) found a preva- the general population (28), there is evidence that lence of 43% by retrospectively reviewing the medical insulin resistance may play a major pathophysiological charts of 106 PCOS women attending the Endocrine role in the development of glucose intolerance in PCOS Clinic in Richmond, Virginia, USA. Both these studies, women also. The decrease of insulin sensitivity in PCOS therefore, described a prevalence of the metabolic appears, in fact, to be quite similar to that found in syndrome in PCOS nearly twofold higher than that patients with type 2 diabetes and to be relatively reported in the general population investigated in the independent of obesity, fat distribution and lean body cited NHANES III report (21), matched for age and body mass (5, 6). However, there is strong evidence that weight. Apridonidze et al. (20) have also described obesity, particularly the abdominal phenotype, per se higher free testosterone and lower sex-hormone-bind- represents an important independent risk factor for ing globulin (SHBG) levels in those women with the glucose intolerance in PCOS women (8). Moreover, an metabolic syndrome with respect to those without it, as impaired early phase insulin secretion appears to play a well as a higher prevalence of acanthosis nigricans and role in the development of glucose intolerance in obese a greater tendency to have a family history of PCOS. PCOS, at least in Hispanic-American subgroups (5, 29), These results were in accordance with a cross-sectional particularly when they have a positive family history for population-based study conducted by Korhonen et al. diabetes (29, 30). The prevalence of impaired glucose (22) who reported a different concentration of some sex tolerance and type 2 diabetes described by our group in hormones between premenopausal women with and PCOS women living in various cities in Italy (11) was without the ATPIII-defined metabolic syndrome. We significantly higher than that described in the general recently analyzed 200 selected PCOS women from the population of a similar age (31), but somewhat lower Mediterranean area and found that 18% were charac- with respect to that reported in previous studies, cited terized by the absence of any criteria of the metabolic above, performed on US or Asian PCOS women (23–25). syndrome, 51% had at least two criteria and 31% met This suggests that environmental factors may play a the three criteria according to the ATPIII recommen- dominant role in determining individual susceptibility dations (authors’ unpublished data). Therefore, collec- to metabolic disorders, which is probably more tively, 82% of PCOS women had at least one feature of important than genetic background, as supported by the metabolic syndrome, a finding consistent with a recent long-term epidemiological studies demonstrating very large presence of single or grouped metabolic that the appearance of type 2 diabetes can be prevented abnormalities in this disorder. Compared to those by adequate lifestyle intervention, focusing on dietary without any criteria, the other two groups were habits and increased physical activity (32–33). progressively more obese and had a higher prevalence of the abdominal pattern of fat distribution. In addition, women presenting with the metabolic syndrome were The rationale for using lifestyle inter- characterized by higher systolic and diastolic blood vention and insulin sensitizers in PCOS pressure, higher pulse rate, greater frequency of liver enzyme abnormalities, worsened insulin resistance, What is reported above forms the rationale for using higher glycosylated hemoglobin and a more severe lifestyle interventions and insulin sensitizers in the hyperandrogenemia (higher free androgen index and treatment of PCOS (34). The lifestyle approach appears lower SHBG concentrations) with respect to those to be particularly useful in the presence of obesity.

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However, the treatment of obesity with behavioral management of PCOS should be encouraged before any modification of dietary habits and physical activity is pharmacological treatment. Although the literature often discouraging, owing to the very high rates of does not include many reports on the effect of weight weight relapse after weight loss regimens and, primarily, loss in obese women, all studies nonetheless demon- to the difficulty of maintaining dietary compliance in the strate that weight loss improves both endocrine and long term. For these reasons, many institutions and metabolic abnormalities and that ovulation and fertility companies have made a great effort in the last few years may be significantly restored. Several studies have in to search for safe drugs, capable of reducing body fact demonstrated a beneficial impact of dietary-induced weight by at least 10%, and chiefly favoring weight weight loss on insulin resistance and hyperinsulinemia maintenance in the long term. This does not represent in PCOS women. In a first non-controlled study (39) we an unachievable goal, as has been demonstrated by the evaluated 20 obese anovulatory women, of whom 14 Swedish Obesity Study, a 15-year controlled prospective exhibited PCOS and 6 exhibited hyperandrogenism- project aimed at evaluating the long-term efficacy of insulin resistance-acanthosis nigricans syndrome, weight loss produced by bariatric (gastric) surgery on before and after an average of 8 months on a health, obesity-associated comorbidities, quality of life hypocaloric dietary regimen. After a mean weight loss and many other factors (34). This study clearly of approximately 9.7 kg, glucose-stimulated insulin demonstrated that intentional weight loss in obese levels significantly decreased, consistent with an patients markedly improved metabolic abnormalities, improvement of insulin sensitivity. The beneficial effect reduced the 10-year incidence of diabetes and dyslipi- of diet-induced weight loss on fasting and glucose- demia (35) and the 8-year incidence of hypertension stimulated insulin levels was subsequently confirmed by (36), and was associated with reduced medications and other controlled and non-controlled studies (reviewed in therefore medication costs for diabetes and cardiovas- Ref. 34). Dietary-induced weight loss also has important cular diseases (37). Unfortunately, long-term studies beneficial effects on androgen levels and related clinical focusing on the treatment of obese PCOS women are still features. Harlass and coworkers (40) first reported an lacking. However, short-term studies on the effects of increase in SHBG along with a decrease in total and free weight loss in obese PCOS women have produced testosterone in a small group of obese anovulatory consistent evidence of the benefits achievable not only women after weight loss ranging from 4.8 to 18%. In in relation to metabolic abnormalities but also fertility. most of the subsequent larger non-controlled studies In fact, weight loss can significantly improve menstrual that we recently reviewed (34), a significant reduction cycles and ovulation, thereby favoring pregnancy in in total and free testosterone levels was confirmed after otherwise infertile obese PCOS women. Since infertility diet-induced weight loss. Accordingly, diet-induced represents a major complaint of adult PCOS women, reduction of body weight has been demonstrated to weight loss should therefore be encouraged in all obese decrease the activity of P450c17a,akeyenzyme anovulatory PCOS women wishing to become pregnant, involved in ovarian androgen synthesis (41). The key regardless of whether these women are willing to treat factors responsible for all these effects appear to be the their obesity in the long term. This should ultimately reduction of insulin levels associated with an improve- increase patient compliance with short-term weight- ment in the insulin-resistant state. Notably, weight loss reducing treatment. does not alter androgen concentrations in non-PCOS The use of insulin sensitizers follows the same obese women (41), therefore confirming that the over- reasoning, since it has been clearly demonstrated that stimulation of ovarian steroidogenesis by inappropri- a decrease in insulin concentration, as a result of ately high circulating insulin is a specific feature of improved insulin resistance, may have important effects PCOS. The reduction of leptin concentrations after on hyperandrogenism, metabolic alterations and, par- weight loss may represent an additional mechanism ticularly, on fertility. In addition, insulin sensitizers can favoring the decrement of ovarian steroid secretion in be added to lifestyle intervention, when obesity is obese PCOS women, leptin being involved in the present, although there is preliminary evidence that regulation of endocrine ovarian function (8). some behavioral modification in dietary habits may Hirsutism tends to significantly decrease in most obese have a positive effect even in normal-weight insulin- PCOS women after weight loss (8). Moreover, weight resistant PCOS women (38). In the majority of available reduction also seems to have potential benefits on lipid studies, however, insulin sensitizers have been investi- abnormalities, as an increase in HDL-cholesterol and a gated as the sole treatment or in combination with decrease in triglyceride concentrations have been other drugs, such as oral contraceptives and antiandro- described (8). Finally, evidence exists that dietary- gens, but not with lifestyle interventions. The following induced weight loss may improve both menses abnorm- sections will summarize available knowledge in this alities and spontaneous ovulation in the majority of field. affected women (40, 42–44). However, it should be noted Because obesity affects many women with PCOS and that available data on the consequences of weight loss on may independently affect the adverse health conse- menses and ovulatory abnormalities among obese quences of PCOS, the role of weight reduction in the women with PCOS were obtained from uncontrolled

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Downloaded from Bioscientifica.com at 09/30/2021 12:05:43PM via free access EUROPEAN JOURNAL OF ENDOCRINOLOGY (2006) 154 Insulin-sensitizing agents in PCOS 767 prospective studies, or from studies including a control pregnancy as a primary outcome. However, in the five group that failed to complete the study program, thereby trials evaluating this aspect, a significant effect for limiting the validity of the results. metformin was described (odds ratio: 4.88; 95% confidence interval, 2.46–9.67). Of these five trials, four had populations known to be previously resistant to clomiphene. Only one trial reported miscarriage rates Insulin sensitizers and multiple pregnancy rates, but neither were significant. A more recent systematic review by Insulin-sensitizing agents have recently been proposed Kashyap et al. (49) reported the same conclusions, as a therapy for the treatment of PCOS. These agents with particular emphasis on the fact that metformin improve insulin action by increasing insulin sensitivity, appears to be effective for the achievement of pregnancy, thereby decreasing hyperinsulinemia. Since almost all when compared to clomiphene citrate. obese PCOS women and more than half of those with The effect of metformin in improving follicle stimulat- normal weight are insulin resistant and present with ing hormone (FSH)-induced ovulation in clomiphene- some degree of fasting or stimulated hyperinsulinemia, resistant PCOS women has not been studied, however, in the use of insulin sensitizers could therefore be the framework of prospective randomized trials with FSH suggested in most patients with PCOS. and placebo as control medications. However, in a randomized prospective trial performed in a small group of clomiphene-resistant PCOS women, De Leo et al.(50) Metformin found that the number of follicles O15 mm in diameter Metformin is the oldest and still the most used insulin on the day of human chorionic gonadotropin (HCG) sensitizer worldwide in the treatment of states of glucose administration was significantly lower in cycles per- intolerance, particularly type 2 diabetes mellitus. It is formed after metformin treatment, as well as the considered an insulin sensitizer since it lowers glucose percentage of cycles with HCG withheld because of levels without increasing insulin secretion. In fact, it excessive follicular development, suggesting a direct effect lowers hepatic glucose production by reducing gluco- of metformin on circulating insulin and/or on ovarian neogenesis and by decreasing glycogenolysis, increases function. These data were not, however, confirmed in a peripheral glucose uptake by skeletal muscle and subsequent study (51). The impact of metformin on adipose tissue and reduces intestinal glucose absorption ovarian response when co-administered during recombi- (45). It is also possible that metformin acts, at least in nant FSH (rFSH) treatment in clomiphene citrate- the presence of diabetes, by improving the effect of resistant PCOS therefore needs further investigation. glucose toxicity and/or lipotoxicity and insulin secretion A recent study has also shown that metformin appears by pancreatic cells (45). to be more effective than laparoscopic ovarian diathermy In women with PCOS, metformin administered at in overall reproductive outcomes in overweight infertile doses of up to 1500 mg/day decreases insulin, testos- clomiphene-resistant women with PCOS (52). terone and LH levels and it also appears to favor some There are also studies that support a potential role of weight loss (46). Some studies have also reported that metformin in favoring significant benefits on primary the degree of hirsutism was attenuated. Most impor- outcomes of in vitro fertilization (IVF) techniques. Since tantly, however, the majority of studies have shown that reduced hyperandrogenemia and insulin resistance in metformin may significantly improve menstrual cycles PCOS women should facilitate FSH stimulation, the and ovulation rates, both spontaneous and clomiphene- parallel administration of metformin before and during induced. Several recent reviews covering all aspects of IVF cycles might be expected to reduce the requirement for metformin therapy are available and readers may refer FSH and improve the quality of embryos, thereby to these for more detailed information (46–49). In a increasing the pregnancy rate. Although the effects of recent meta-analysis performed by Lord et al. (47, 48), metformin on FSH stimulation have been debated in the the effectiveness of metformin in improving clinical and literature in recent years (see Ref. 53 for review), there are biochemical features of PCOS was assessed. The study only a few studies on the effect of metformin on ovarian was performed by including all controlled trials (nZ13) stimulation and IVF in insulin-resistant women with which investigated the effect of metformin compared PCOS (54–56) and only one of these has a prospective with either placebo or no treatment, or compared with double-blind randomized design (56). Two studies an ovulation induction agent. Meta-analysis showed reported that metformin treatment increased the mean that metformin is effective in achieving ovulation in number of mature oocytes (55, 57) and cleaved embryos women with PCOS with an odds ratios of 3.88 (95% (57), and significantly improved fertilization rates and confidence interval, 2.25–6.69) when metformin is clinical pregnancy rates (57) without any effect on the compared to placebo and 4.41 (95% confidence requirement for FSH (55). However, in a prospective, interval, 2.37–8.22) when metformin plus clomiphene double-blind, randomized, placebo-controlled trial, per- is compared to clomiphene alone. Care is needed in formed to evaluate the effect of pretreatment with interpreting pregnancy rates, as no trial measured metformin in a large group of women with PCOS

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Downloaded from Bioscientifica.com at 09/30/2021 12:05:43PM via free access 768 R Pasquali and A Gambineri EUROPEAN JOURNAL OF ENDOCRINOLOGY (2006) 154 scheduled for IVF stimulation (55), no differences were findings clearly show that metformin is an effective found between the two regimens in relation to duration of treatment for anovulation in women with PCOS and FSH stimulation, number of retrieved oocytes, fertilization that it gives some benefits on the parameters of the rates and embryo quality. However, pregnancy rates metabolic syndrome. However, Lord et al. (48) con- following IVF appeared to be significantly higher in the cluded that metformin should be used as an adjuvant of metformin group than in the placebo group. Many more general lifestyle improvements and not as a replacement studies in well-selected PCOS women should therefore be therapy for exercise and diet. The major effects of performed to prove the efficacy of metformin added to IVF metformin are summarized briefly in Table 1. procedures in this syndrome. Most importantly, metformin has also been found to have important benefits on pregnancy rates, although Metformin added to hypocaloric diet this important topic should be investigated much more intensively. Two studies have shown that metformin In one controlled study (64) performed to evaluate the may reduce the rate of first trimester spontaneous additive efficacy of metformin upon a low-calorie diet abortions (58, 59), which is threefold higher in PCOS regimen in abdominally obese women with PCOS, we women with respect to the normal population. Only one found a greater reduction of body weight and study has been performed to investigate the effectiveness abdominal fat, particularly the visceral depots, and a of metformin on pregnancy rates in unselected PCOS more consistent decrease of serum insulin, testosterone patients, although pregnancy was not a primary end and leptin concentrations after metformin (850 mg orally, twice daily) administration when compared to point (60). This large, randomized, double-blind, placebo. Chiefly, in PCOS patients these changes were placebo-controlled study on predominantly obese associated with a significant improvement of hirsutism PCOS patients treated for 16 weeks with metformin and menses abnormalities. These findings are therefore therapy demonstrated, in fact, that 17% of women on consistent with a coordinated role of hyperinsulinemia metformin conceived compared to 5% on placebo, a and abdominal obesity in the pathophysiology of PCOS. result that was not, however, significantly different. In addition, they indicate that metformin may produce Finally, recent data from Vanky et al. (61) have significant additional benefits to weight loss regimens, suggested that metformin, administered during preg- which have considerable relevance at clinical level. nancy, may reduce major fetal complications. In addition, there are studies indicating that, as well as reducing abortion rates, metformin treatment may also be effective in controlling glucose metabolism and Metformin and oral contraceptives gestational diabetes (62). These benefits may theoreti- There are no theoretical contraindications to the use cally be accounted for by the ability of metformin to of metformin with oral contraceptives (OCs) in PCOS reduce insulin and plasminogen-activator inhibitor women. The beneficial effects of metformin on factor type 1 (PAI-1), to increase glycodelin concen- cardiovascular risk factors and on insulin sensitivity trations and to enhance uterine vascularity and blood could justify the addition of metformin to OCs in flow in PCOS women, as recently reviewed (63). PCOS. However, treatment with OC may add Notably, metformin has been extensively proved to be significant efficacy in reducing clinical and biochemi- safe, effective and absolutely free of potential teratogenic cal hyperandrogenism to metformin. In a 6-month effects (46, 63). study comparing the effect of metformin with that of Metformin also has obviously important effects on ethynylestradiolCcyproterone acetate (EECCA) in parameters of the metabolic syndrome. In particular, obese PCOS women, it was found that whereas the majority of controlled studies found a significant metformin significantly decreased waist:hip ratio, decrease in circulating fasting insulin levels (odds ratio: fasting glucose and insulin levels, increased fasting K5.37, 95% confidence interval: K8.11 to K2.63) glucose oxidation and decreased lipid oxidation, (47, 48). In controlled studies using the clamp without any effect on insulin sensitivity measured technique, a significant but incomplete correction of by the euglycemic–hyperinsulinemic clamp technique, insulin resistance was also found (46). The effects of treatment with EECCA slightly worsened glucose metformin on lipids were investigated in some studies, tolerance, without, however, any change in insulin and, although a significant improvement was observed sensitivity, while it significantly decreased serum in both triglyceride and HDL-cholesterol concen- androgen levels (65). In another study performed trations, a large variability was nonetheless described by the same group (66) in non-obese PCOS women, among groups and individuals (48). Other studies metformin led to effects similar to those in obese showed an improvement of pro-inflammatory markers, PCOS women, and also improved menses cycles by such as PAI-1, endothelin, and c-reactive protein (46). approximately 50%, whereas EECCA significantly Although metformin was associated with a signifi- decreased androgens and the LDL:HDL ratio, cantly higher incidence of gastrointestinal discomfort, increased triglycerides and c-reactive protein, but no serious adverse effects were reported. All these did not influence glucose tolerance and insulin

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Table 1 Potential benefits of metformin and thiazolidinediones, given alone or in combination with lifestyle intervention, in PCOS women (references are given in parentheses).

Parameter Metformin Thiazolidinediones (troglitazone, rosiglitazone, pioglitazone)

Body weight Unchanged or slightly reduced Unchanged or slightly increased (46, 98, 101) (41, 46, 47) Glucose tolerance Improved (45) Improved (86, 88) Insulin sensitivity Improved (46, 47) Improved (6, 87, 101) Lipids ! triglycerides (46, 47) ! triglycerides (46) O HDL-C (46, 47) O HDL-C (46) Menses Improved (46, 47) Ovulation rate Spontaneous Improved (46–49) Improved (46, 82, 86, 89–97) Clomiphene induced Improved (46–49) Improved (86, 87) Other treatments Improved (49, 51) Hirsutism Unchanged or slightly reduced (46) Unchanged or slightly reduced (89) Androgen and SHBG Testosterone Slightly reduced (46, 47) Slightly reduced (87–89, 90–98) Free testosterone Slightly reduced (46, 47) Slightly reduced (87–89, 90–98) SHBG Unchanged or increased (41) Increased (47, 87) Androstenedione Slightly reduced (46) Slightly reduced (87, 88) DHEA-S Unchanged (46) Unchanged (87, 88) Pregnancy rates Spontaneous Improved (47, 53, 60) Improved (46, 98) After ART Improved (54–57) NA Miscarriage rates Reduced (47, 58, 59) NA Fetal complications Reduced (61)* NA

NAZnot available, ARTZassisted reproductive technology. HDL-C, HDL-cholesterol; DHEA-S, dehydroepiandrosterone-sulfate; SHGB, sex-hormone-binding globulin. *Literature insufficient. sensitivity. Some studies compared OCs with the Metformin and antiandrogens combined therapy of OCs and metformin. Elter et al. (67) found that the combined therapy led to a Treatment with antiandrogens is also effective in PCOS. Notably, antiandrogens markedly reduce androgens greater decrease in androstenedione and to a more (71–74) and improve gonadotropin secretion (75) and pronounced increase in SHBG, without any signifi- hirsutism (71–74), but no significant effects have been cant difference on changes in body mass index (BMI), described on ovulation and fertility (76). Several studies waist:hip ratio and glucose:insulin ratio. In another have shown that antiandrogens may also improve the study performed in a larger group of PCOS women, lipid profile (74, 76), whereas it is still unclear whether Vrbikova and Cibula (68) confirmed these findings. In this treatment can reduce insulin resistance (72, 74, 77). particular, they did not find any change in insulin As summarized above, there is evidence that hyperan- sensitivity, measured by the euglycemic–hyperinsuli- drogenism, insulin resistance and associated hyperinsu- nemic clamp technique. The combination of OCs with linemia and obesity play key and coordinating roles in the metformin thus appears to further decrease androgen pathogenesis of PCOS, contributing in different ways to levels, without any additional effect on insulin the clinical expression of the syndrome. Due to their sensitivity. specific actions, insulin sensitizers and antiandrogens are Available data do not, however, offer enough therefore thought to display potential complementary evidence to advocate the use of OCs in combination effects in the treatment of PCOS. with metformin in the treatment of PCOS. One To investigate this possibility, we carried out a particular concern is that the effect of OCs on glucose randomized, prospective, 6-month placebo-controlled metabolism and insulin sensitivity in PCOS is still study analyzing the effect of long-term treatment with controversial, and in most studies insulin resistance did metformin and flutamide, administered alone or in not change or even improve (69, 70). By contrast, it is combination and added to a low-calorie diet, on body important to outline that patients often complain of weight and fat distribution, androgens, metabolic hirsutism and other hyperandrogenic features, where parameters and clinical status in 40 obese women with OCs have demonstrated their efficacy beyond those on PCOS (77). After a 1-month diet, patients were allocated insulin sensitivity. Therefore, the use of OCs with or to treatment with placebo, metformin (850 mg/orally, without metformin should be carefully evaluated twice daily), flutamide (250 mg/orally, twice daily) or according to individual requirements that include the metformin (850 mg/orally, twice daily) C flutamide need for contraception and improvement of metabolic (250 mg/orally, twice daily) for the following 6 months, derangements. while continuing hypocaloric dieting. Overall, our

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findings suggest that the addition of metformin, any significant difference in BMI, fasting glucose, insulin, flutamide or the combined metforminCflutamide treat- c-peptide and lipid. This study therefore suggests an ment had some additional favorable effects with respect additional benefit of low-dose dexamethasone on hyper- to the low-calorie diet alone. In particular, flutamide androgenism in women with PCOS otherwise treated with treatment seemed to add a significant effect in decreasing lifestyle intervention and metformin. visceral fat, androgens, total and low LDL-cholesterol and in improving hirsutism. Conversely, metformin had significant benefits on menstrual status. The two drugs Thiazolidinediones showed an additional effect in reducing testosterone The insulin-sensitizing thiazolidinediones are selective concentrations and a synergistic effect in increasing ligands of the nuclear transcription factor peroxisome- HDL-cholesterol and SHBG levels. Improvement of proliferator-activated receptor g (PPARg), which is insulin sensitivity and hyperinsulinemia appeared, expressed most abundantly in adipose tissue, but is also however, to depend on hypocaloric diet, without any found in pancreatic beta cells, vascular endothelium and further significant effect of the pharmacological treat- macrophages (85). The first approved thiazolidinedione ments, either alone or in combination. We recently was troglitazone, subsequently withdrawn from the extended these data with a larger group of obese PCOS market due to hepatotoxicity.The two currently available women, treated with the same protocol for 12 months PPARg agonists are rosiglitazone and pioglitazone. (78). After that time, flutamide maintained the same Thiazolidinediones exert their insulin-sensitizing actions significantly greater effects on visceral fat and androgen through two mechanisms: directly, by the so-called ‘fatty levels than placebo, further improved hirsutism and acid steal’ hypothesis, and indirectly, by increasing the displayed significant efficacy in reducing glucose-stimu- expression of adiponectin, an adipocytokine with an lated insulin levels. Metformin treatment maintained the insulin sensitivity effect, and probably by decreasing the same positive effects shown after the 6-month period, expression of 11b-hydroxysteroid dehydrogenase type 1, chiefly in improving menstrual cycles. Interestingly, an enzyme which catalyzes the conversion of inactive however, the combined therapy further and significantly cortisone to active cortisol (86). According to the ‘fatty improved insulin resistance, which suggests that long- acid steal’ hypothesis, thiazolidinediones promote fatty term sustained decrease of androgen excess may favor acid uptake and storage in adipose tissue. In this way,they improvement of insulin sensitivity. increase adipose-tissue mass and spare other insulin- The administration of metformin and flutamide, sensitive tissues such as skeletal muscle and the liver, and either alone or in combination, therefore appears to be possibly pancreatic beta cells, from the harmful metabolic a promising way of treating dieting obese PCOS women. effects of high concentrations of free fatty acids (86). Preliminary data support this approach even in young Most clinical studies evaluating the effect of thiazolidi- normal-weight PCOS women (73). Flutamide, however, nediones on PCOS have been performed with troglitazone. is not considered completely safe, because of its potential A few recent studies are available using rosiglitazone and teratogenic properties, at least in experimental animals pioglitazone. Obese PCOS women who took troglitazone (79). For this reason, its use should still be restricted to had consistent improvements in insulin resistance, preclinical research activity, provided written and glucose tolerance and hyperandrogenemia (free testoster- informed consent is obtained from the patients. one, androstenedione, DHEA-S) (87, 88). Ovulation was also positively influenced by the administration of this Other combinations with metformin drug (89). In particular, troglitazone alone resulted in ovulatory rates of O40%, and the success rate of In consideration that some PCOS women may have clomiphene increased from 35 to 75% with troglitazone increased adrenal androgen synthesis in response to pretreatment (89). Moreover, the use of troglitazone in adrenocorticotropin (ACTH), demonstrating increased clomiphene-resistant patients resulted in ovulation and activity of the pituitary–adrenal axis (80), the use of pregnancy rates of 83 and 39%, respectively (90). In corticosteroids to treat menses abnormalities (80), addition, troglitazone treatment was associated with a ovulatory dysfunction (81) or androgen excess (82, 83) reduction in levels of PAI-1 (88, 91), and with a relative has been reported by some authors, with success. improvement in endothelium-dependent vasodilation Recently, a 26-week prospective, randomized, double- (91), which correlated with the reduction in insulin blind, placebo-controlled study was carried out by Vanky levels. Recently, a large-scale, double-blind, placebo- et al. (84) in which PCOS women received either controlled trial including 305 obese PCOS women dexamethasone (0.25 mg daily) or placebo in addition confirmed previously shown results. In particular, it to diet and lifestyle counseling in combination with demonstrated that troglitazone administration was metformin 850 mg three times daily throughout the associated with significant improvements in insulin study. This study demonstrated that dexamethasone resistance and hyperinsulinemia, hyperandrogenemia, reduced testosterone, androstenedione, dehydroepian- hirsutism and ovulatory function in a dose-dependent drosterone-sulfate (DHEA-S) and free testosterone index manner (92). An interesting analysis performed by the by approximately 20–50% more than placebo, without authors was the determination of factors predicting

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Downloaded from Bioscientifica.com at 09/30/2021 12:05:43PM via free access EUROPEAN JOURNAL OF ENDOCRINOLOGY (2006) 154 Insulin-sensitizing agents in PCOS 771 ovulation after troglitazone treatment. Patients with a non-obese (100) women. In the first prospective study higher ovulatory rate were older and less obese before (109), pioglitazone was added to metformin for 10 entering the study, and had lower fasting insulin levels, months in 13 dieting obese women not responsive to a lower free testosterone and higher SHBG levels than 12-month treatment with metformin alone. When patients with low ovulatory rates, suggesting that women pioglitazone was added to metformin, insulin and who are more affected by the syndrome are also less glucose, insulin resistance and DHEA-S fell, HDL- responsive to treatment. Finally,although pregnancy was cholesterol and SHBG rose, and menstrual regularity not an outcome measure of this study, troglitazone- improved with respect to the previous metformin treated subjects had a fourfold greater fertility rate administration. In the second randomized double- compared to the placebo group (18 vs 4%) (92). blind study (100), a 6-month treatment with rosiglita- Similar data regarding improvement in insulin zone and metformin did not prove more potent than the resistance and hyperinsulinemia, hyperandrogenism monotherapies in improving ovulation and hyperan- and ovulation observed with troglitazone administration drogenemia in normal-weight non-insulin-resistant were subsequently reported in smaller studies in which PCOS women. These results may suggest that the obese PCOS women underwent treatment with rosigli- combined therapy could only be useful in the subset of tazone (93–97) and pioglitazone (98, 99). Rosiglitazone PCOS women with insulin resistance, probably depend- was found to increase ovulatory frequency and improve ing on the different insulin-sensitizer action of the two hyperandrogenemia even in non-obese women with drugs. Table 1 summarizes the potential additive effects PCOS with normal insulin sensitivity (100). However, of thiazolidinediones added to metformin based on when compared with metformin, the effect of rosiglita- available studies. zone in improving frequencies of ovulation was lower, whereas the effect of the two drugs on hyperandrogen- emia was similar (100). Similar results were found by New potential drug: somatostatin analogs comparing the effect of pioglitazone with that of Somatostatin is a 14-amino acid endogenous hypo- metformin in a group of obese women with PCOS, thalamic peptide with a short half-life that, besides where both drugs decreased insulin resistance and blunting the LH response to gonadotropin-releasing hyperandrogenemia to the same extent (101). hormone (GnRH) (110) and decreasing growth hor- Although most evidence indicates that the reduction mone (GH) pituitary secretion (111), inhibits pancreatic in insulin levels is responsible for decreased concen- insulin release (112). Somatostatin analogs should trations of circulating androgens and, therefore, for therefore be potential drugs for the treatment of PCOS. improvement of hyperandrogenism, the thiazolidine- In 1990 Prelevic and colleagues (113) showed that a diones may affect hyperandrogenemia by reducing 7-day administration of octreotide, a synthetic somato- ovarian steroid synthesis directly (102), and, probably, statin analog with a half-life of 80–110 min, decreased by decreasing adrenal androgen secretion, as suggested fasting and glucose-stimulated insulin concentrations by the reduction of DHEA-S levels (87, 103) and by the in ten PCOS women, mostly obese. More recently, a few decrease of 17-hydroxyprogesterone and androstene- other prospective non-controlled short-term studies dione responsiveness to ACTH (104) after troglitazone using octreotide (114–121) confirmed these findings and pioglitazone administration, respectively.To support and definitively demonstrated the ability of octreotide to the hypothesis of a direct effect of thiazolidinediones on reduce insulin levels in PCOS patients. These studies ovarian steroidogenesis, there is the observation that also showed that administration of octreotide in PCOS troglitazone decreases androgen biosynthesis in primary improved pulsatile gonadotropin patterns, reduced LH, cultures of ovary cells (102) by inhibiting cholesterol androgen and IGF-I levels (114–121), and increased biosynthesis (105) and P450c17 enzyme expression and spontaneous (122) and stimulated ovulation (116, activity (106, 107), and by the finding of PPARg at 121). Unfortunately, the daily multiple s.c. injections ovarian level (108). The positive effect exerted by required by the short life of octreotide makes this thiazolidinediones on ovulation is also probably related procedure inappropriate for long-term treatment. We to a direct effect of the drug at ovarian level, as well as to a recently carried out a placebo-controlled study to reduction of insulin resistance and hyperinsulinemia. evaluate the effect of prolonged therapy with a long- The major effects of thiazolidinediones are also briefly acting somatostatin analog formulation release (octreo- summarized in Table 1. tide-LAR), injected i.m. every 28 days, in a selected group of anovulatory PCOS women with abdominal The combination of metformin and obesity (123). Octreotide-LAR consists of octreotide thiazolidinediones acetate encapsulated with a biodegradable polymer (124). Its slow and constant drug release into the So far, only two studies have evaluated the effect of a circulation makes it possible to improve patient combined treatment with metformin and thiazolidine- compliance by avoiding repeated daily s.c. injections diones on PCOS, one performed in insulin-resistant (115). An additional advantage of this formulation is obese (109) and the other in non-insulin-resistant a lowering in the occurrence of side-effects, such as

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Downloaded from Bioscientifica.com at 09/30/2021 12:05:43PM via free access 772 R Pasquali and A Gambineri EUROPEAN JOURNAL OF ENDOCRINOLOGY (2006) 154 gallstone formation (115). We found that the addition of 14 Hofman PL, Cutfield WS, Robinson EM, Bergman RN, Menon RK, octreotide-LAR significantly amplified the effects of a Sperling MA & Gluckman PD. Insulin resistance in short children with intrauterine growth retardation. Journal of Clinical Endo- low-calorie diet in decreasing fasting and crinology and Metabolism 1997 82 402–406. glucose-stimulated insulin levels and the insulin- 15 Phillips DI. Insulin resistance as a programmed response to fetal resistance state. This finding is consistent with the undernutrition. Diabetologia 1996 39 1119–1122. previously reported efficacy of octreotide to directly 16 Pasquali R, Gambineri A, Anconetani B, Vicennati V, Colitta D, influence insulin secretion (112, 125), and, thus, with Caramelli E, Casimirri F & Morselli-Labate AM. 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Restored insulin strong efficacy in improving the ovulatory rate, as all sensitivity but persistently increased early insulin secretion after women treated with octreotide-LAR ovulated, compared weight loss in obese women with polycystic ovary syndrome. to only one of those receiving placebo. This effect seems Journal of Clinical Endocrinology and Metabolism 1995 80 to be the consequence of the improvement in hyper- 2586–2593. 19 Glueck CJ, Papanna R, Wang P, Goldemberg N & Sieve-Smith L. insulinemia, as well as of a direct effect of octreotide on Incidence and treatment of metabolic syndrome in newly referred the ovaries, as suggested by the recent discovery of women with confirmed polycystic ovarian syndrome. Metabolism somatostatin receptors at ovarian level (126). 2003 52 908–915. 20 Apridonidze T, Essah P, Iourno MJ & Nestler JE. Prevalence and characteristics of the metabolic syndrome in women with PCOS. Journal of Clinical Endocrinology and Metabolism 2005 90 1929–1935. 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