Prevalence and Determinants of Diabetic Retinopathy and Cataracts in West African Type 2Diabetes Patients

PREVALENCE AND DETERMINANTS OF DIABETIC RETINOPATHY AND CATARACTS IN WEST AFRICAN TYPE 2DIABETES PATIENTS

Objective: To quantify the prevalence of, and Charles Rotimi, PhD; Harold Daniel, MD, PhD; risk factors for, diabetic retinopathy and cataracts in patients with type 2 diabetes, and their Jie Zhou; Augustine Obisesan, BS; Guanjie Chen, MD, MPH; spouse controls, enrolled from 5 centers in 2 Yuanxiu Chen, MD PhD; Albert Amoah, MD; West African countries (Ghana and Nigeria). Victoria Opoku, MD; Joseph Acheampong, MD;

Method: The analysis cohort was made up of Kofi Agyenim-Boateng, MD; Benjamin Ackon Eghan Jr, MD; 840 subjects with type 2 diabetes, and their Johnnie Oli, MD; Godfrey Okafor, MD; Ester Ofoegbu, MD; 191 unaffected spouse controls, who were en- Babatunde Osotimehin, MD; Fayeofori Abbiyesuku, MD; rolled and examined in Lagos, Enugu, and Iba- dan, in Nigeria, and in Accra and Kumasi, in Thomas Johnson, MD; Olufemi Fasanmade, MD; Ghana. A diagnosis of diabetic retinopathy was Ayo Doumatey, MS; Temilolu Aje, BS; made only where a participant had a mini- Francis Collins, PhD, MD; Georgia Dunston, PhD mum of one microaneurysm in any field, as well as exhibiting hemorrhages (dot, blot, or flame shaped), and maculopathy (with or without clinically significant edema). INTRODUCTION tography, indicated that 23% of patients Results: Average duration of diabetes was 7.0 had retinopathy with diabetes of less years, and mean age at diagnosis was 46.5 Diabetic retinopathy is the leading than 2 years duration.6 At the time of years. Prevalence of diabetic retinopathy was cause of blindness in adults between the diagnosis, about 21%–29% of patients 17.9%. Cataracts were present in 44.9% of the with type 2 diabetes in the United States patients with type 2 diabetes, and in 18.3% of ages of 20 and 65 in industrialized 1,2 and Europe have retinopathy.3,4,7 Nearly spouse controls. The risk of developing reti- countries. The condition probably be- nopathy increased more than 3-fold for pa- gins early in diabetes, approximately 4 50% of all patients with diabetes will tients at the highest fasting plasma glucose to 7 years prior to clinical diagnosis. develop some form of diabetic retinop- (FPG) level (ORϭ3.4; 95% CI, 1.8–6.3), com- This is particularly the case with type 1 athy, and 65% to 74% of those who pared to patients at the lowest FPG level. The diabetes, where it is unusual to see ret- have diabetes for 10 years or longer will odds ratios for persons with diabetes for 10 show clinical evidence of diabetic reti- years or more, compared to persons with di- inal lesions in patients who have the dis- 3–5 4,7,8 abetes for less than 5 years, was 7.3 (95% CI, ease for less than 5 years. However, nopathy. In type 1 diabetes, diabetic 4.3–12.3) for retinopathy, and 2.6 (95% CI, findings from the Wisconsin Epidemi- retinopathy occurs in 90% of patients 1.5–4.5) for cataracts. ology Study, which utilized retinal pho- who have had the disease for 10 years or longer.8 Conclusions: Cataracts were a more impor- Though diabetic retinopathy pro- tant cause of vision impairment than was dia- From the National Human Genome gresses predictably, in some patients, it betic retinopathy in this cohort. The preva- Center at Howard University, College of lence of cataracts in patients with diabetes was advances rapidly and inexorably toward Medicine, Washington, DC (CR, HD, JZ, vision loss, even with early detection, more than twice that of their spouse controls, AO, GC, YC, AD, TA, GD); University of indicating that type 2 diabetes is an important Ghana Medical School, Department of follow-up, and adequate treatment, risk factor for cataract formation. Individuals Medicine, Accra (AA, VO), University of Sci- while the condition remains unchanged who developed type 2 diabetes at an earlier ence and Technology, Department of Med- for many years in other patients. The age were more likely to develop both diabetic icine, Kumasi, (JA, KA, BAE) Ghana; Uni- reasons for the observed differential pro- retinopathy and cataracts. A strong positive as- versity of Nigeria Teaching Hospital, De- gress toward development of retinopa- sociation was observed between FPG level, partment of Medicine, Enugu (JO, GO, ED), duration of diabetes, and risk of retinopathy University College Hospital, Department of thy are not clear. Puberty and cataract and cataracts. The low prevalence of retinop- Chemical Pathology, Ibadan (BO, FA), Uni- surgery can accelerate all of the retinal athy and cataracts observed within the first 5 versity of Lagos, College of Medicine, En- changes in diabetes, and pregnancy years of diagnosis of diabetes in this cohort, docrine and Metabolic Unit, Lagos (TJ, OF), makes diabetic retinopathy particularly suggests that intensive blood glucose control Nigeria; National Human Genome Re- 9–12 may reduce the risk of the development and search Institute, National Institutes of aggressive. Gender does not appear progression of retinopathy and cataracts. In Health, Bethesda, Maryland (FC). to significantly affect the prevalence, in- this regard, early eye examination, preferably cidence, or rate of progression of dia- at first presentation of elevated blood glucose, Address correspondence to Charles Ro- betic retinopathy in older-onset people; is highly recommended. (Ethn Dis. 2003; timi; National Human Genome Center, however, the frequency of proliferative 13[suppl2]:S2-110–S2-117) Howard University; Genetic Epidemiology Unit, College of Medicine; 2216 6th Street, retinopathy is higher among younger- 6,13–15 Key Words: Type 2 Diabetes, Retinopathy, NW; Washington, DC 20059; 202-806-5419; onset males, compared to females. Cataracts, West Africa 202-806-2254 (fax); [email protected] The impact of obesity, a major risk fac-

S2-110 Ethnicity & Disease, Volume 13, Spring 2003 DIABETIC RETINOPATHY AND CATARACTS - Rotimi et al tor for the development of type 2 dia- Diagnosis of type 2 diabetes was betes, on the prevalence or severity of . . . the increasing prevalence based on criteria established by the diabetic retinopathy, has not been well American Diabetes Association Expert established.16–20 of diabetes worldwide, Committee41: exhibiting either a fasting The prevalence of retinopathy in pa- especially in developing plasma glucose (FPG) concentration of tients with type 2 diabetes demonstrates Ն126 mg/dL (7.0 mmol/L) on more 26 wide variations between countries: in countries, combined with than one occasion, or a 2-hour post load Ն Europe, it ranges from 17% in Switzer- the worsening healthcare value 200 mg/dL (11.1 mmol/L) on land, 39% in Sweden, to approximately more than one occasion, and/or phar- 52% in the United Kingdom.21,22 Dia- situation in sub-Saharan macological treatment of diabetes, with betic retinopathy is probably the result adequate justification from medical re- of microvascular dysfunction induced Africa, may elevate the cords. Elevation of FPG concentration by hyperglycemia. Several studies have already high rate of all-cause was the preferred criterion; OGTT con- demonstrated that poor diabetes control firmation was required in patients with predisposes individuals to and is detri- blindness. FPG below 126 mg/dL who had other mental to diabetic retinopathy.6,23,24 The clinical evidence suggestive of diabetes. expected high level of poor diabetes Detection of auto-antibodies to GAD, a control in Africa could make diabetic level of fasting C-peptide Ͻ0.03 mmol/ among Africans with access to health retinopathy a major problem in diabetes L, and absent history of type 1 diabetes care in urban areas.27–39 In this study, we care. (ie, age below 25 years, insulin depen- used standardized screening methods in dence, and repeated episodes of keto- 5 urban and suburban centers across 2 acidosis), were used to exclude probable West African countries, excluding, to DIABETIC RETINOPATHY cases of type 1 diabetes. Non-diabetic the extent possible, patients with type 1 IN AFRICA spouse controls (FPG Ͻ110 mg/dL or diabetes. 2-hour post load value Ͻ140 mg/dL) Though diabetic retinopathy is a were also enrolled. leading cause of blindness in industri- RESEARCH DESIGN AND Eye Examination alized countries, in sub-Saharan coun- METHODS tries, other causes of blindness, such as Eye examination was part of a com- vitamin A deficiency, trachoma, and on- Our cohort was made up of siblings prehensive physical examination of each chocerciasis, decrease the proportional (840 individuals) with type 2 diabetes, participant in the study. Each partici- contributions of diabetic retinopathy as and their unaffected spouse controls pant had the following ocular exami- a cause of loss of sight.25 However, the (Nϭ191), who were enrolled and ex- nations: visual acuity; ocular alignment increasing prevalence of diabetes world- amined in 5 sites in 2 West African and motility; pupil reactivity and func- wide, especially in developing coun- countries (Lagos, Enugu, and Ibadan, in tion; visual fields; intraocular pressure; tries,26 combined with the worsening Nigeria, and Accra, and Kumasi in Gha- slit lamp examination of the cornea, iris, healthcare situation in sub-Saharan Af- na). This investigation is part of an on- lens and vitreous; and dilated fundus ex- rica, may elevate the already high rate of going research effort, the Africa America amination. all-cause blindness. Diabetes Mellitus (AADM) Study, the Due to the large number of partici- Reports about the specific contri- goal of which is to identify susceptibility pants and limited resources, retinal pho- butions of type 2 diabetes to blindness genes for type 2 diabetes in West Afri- tography was excluded as a diagnostic in Africa are limited. Similarly, reports cans. The details and rationale of the tool. Previous experiences of the oph- from Africa on the prevalence of dia- sampling approach have been described thalmologists in the 5 centers demon- betic retinopathy are limited, due to in- elsewhere.40 Briefly, with informed con- strate a better than 80% concurrence adequate screening, lack of adequate sent, detailed epidemiological, family, between their clinical and photographic screening technology, and the high rate and medical, information was obtained assessment of the presence and absence of mortality. Available reports come from eligible participants. Blood sam- of lesions associated with diabetic reti- mainly from small scale studies that of- ples were also obtained from each par- nopathy. To assure reproducibility of the ten include patients with type 1 or type ticipant for biochemical measurements, assessment and classification of ocular 2 diabetes. These factors probably ex- including glucose, and C-peptide, and complications between the 5 centers, plain the wide range (9%–55%) of the in order to detect autoantibodies to glu- the absence and/or presence of hemor- prevalence of diabetic retinopathy tamic acid decarboxylase (GAD). rhages, microaneurysms, cotton wool

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from 20 to 79 years). Mean FPG was Table 1. Distribution of study participants by center, country and type 2 diabetes Ϯ status: The Africa America Diabetes Mellitus (AADM) Study 197.8 91.2 mg/dL for cases, and 94.0 Ϯ 18.3 mg/dL for the controls. The Centers Cases Controls mean C-peptide value was 1.3 Ϯ 0.75 Nigeria: Lagos (% males) 186 (51%) 45 (29%) mmol/L for cases, and 1.23 Ϯ 0.80 Ibadan 149 (57%) 27 (22%) mmol/L for the controls. A large pro- Enugu 167 (50%) 43 (28%) Ghana: Accra (% males) 166 (33%) 32 (47%) portion of cases (73%) had fasting Kumasi 172 (23%) 44 (64%) blood glucose levels greater than the di- Total 840 (43%) 191 (39%) agnostic value of 126 mg/dL. Mean body mass index (BMI) was 25.0 Ϯ 4.3 kg/m2 for men, and 27.5 Ϯ 5.8 kg/m2 for women. Remarkably, the spots, neovascularization, cataracts, ret- this report, 840 cases were enrolled (sur- inal detachment, maculopathy, and passing the study goal), along with 191 mean BMI of cases did not differ sig- glaucoma, in each subject’s eyes was re- spouse controls. With slight variation, nificantly from that of controls, presum- corded, along with other ocular abnor- the distributions of cases and controls ably reflecting the effect of the same malities. A diagnosis of diabetic retinop- were similar across the 5 centers. family household environment (‘‘eating athy was made only where a participant Selected characteristics of the cohort from the same pot’’), since the controls had a minimum of one microaneurysm by type 2 diabetes status are shown in were spouses of the cases. About 40% in any field, in addition to exhibiting Table 2. The distribution of men and of both cases and controls had BMI val- hemorrhages (dot, blot, or flame women was similar for cases and con- ues greater than 27, making this cohort shaped) and maculopathy (with or with- trols (Pϭ.34), and, on average, the con- significantly heavier than the general out clinically significant edema). For the trols were 4 years younger than the cases population of Nigeria and Ghana. same reason of reproducibility, no at- (49.4 vs 53.5 years, respectively; P More than half (53%) of the pa- tempts were made to classify retinopa- Ͻ.0001). Approximately 50% of the tients with type 2 diabetes were also hy- thy into the conventional stages of non- cases had exhibited type 2 diabetes for pertensive, compared to 37% among proliferative and proliferative maculop- 5 years or less. The average duration of the controls; hypertension was defined athy, with or without edema. type 2 diabetes was 7.0 years (ranging as systolic blood pressure (BP)ϭ140 from 0 to 46 years), and the average age mm Hg and/or diastolic BPϭ90 mm Statistical Analysis at diagnosis was 46.5 years (ranging Hg, or taking concomitant anti-hyper- All statistical analyses were per- formed using the SAS statistical package (Cary, NC). Frequency differences were Table 2. Selected characteristics of West African diabetic patients and control par- evaluated by the chi-square (␹2) proce- ticipants: The AADM study dure. Differences in group means were Variables Male (Mean ؎ SD) Female (Mean ؎ SD) P Value tested using the t test. Statistical signif- CASE icance occurred if a computed 2-tailed Age 53.9 Ϯ 10.6 53.2 Ϯ 10.9 .3201 probability value was less than 5% (P Ͻ Waist-hip ratio 0.94 Ϯ 0.07 0.90 Ϯ 0.07 Ͻ.0001 .05). Logistic regression was used to Body mass index 24.8 Ϯ 4.1 27.3 Ϯ 5.4 Ͻ.0001 evaluate excess risk for selected variables, Insulin 19.6 Ϯ 7.2 23.0 Ϯ 30.9 .1386 C-peptide 1.13 Ϯ 0.74 1.36 Ϯ 0.78 .0002 including FPG level, duration of dia- Leptin 4.7 Ϯ 5.6 24.5 Ϯ 20.7 Ͻ.0001 betes, blood pressure level, age, and sex. Glucose 195.0 Ϯ 94.3 199.7 Ϯ 86.3 .5086 Systolic BP 135.4 Ϯ 22.0 138.1 Ϯ 25.2 .0959 Diastolic BP 83.5 Ϯ 12.0 83.27 Ϯ 13.2 .7800 RESULTS CONTROL Age 56.0 Ϯ 11.6 45.2 Ϯ 9.6 Ͻ.0001 Ϯ Ϯ The distribution of participants by Waist-hip ratio 0.91 0.10 0.86 0.07 .0008 Body mass index 25.0 Ϯ 4.3 27.6 Ϯ 6.1 .0009 center is shown in Table 1. The goal of Insulin 13.0 Ϯ 11.1 18.3 Ϯ 16.4 .0405 the AADM parent study was to enroll C-peptide 1.18 Ϯ 0.79 1.28 Ϯ 0.82 .5260 160 volunteers with type 2 diabetes, Leptin 7.9 Ϯ 11.9 32.7 Ϯ 26.4 Ͻ.0001 Ϯ Ϯ along with 40 spouse controls, at each Glucose 94.7 11.2 93.8 21.3 .7648 Systolic BP 136.6 Ϯ 22.2 127.3 Ϯ 21.3 .0050 center, for a total of 800 cases and 200 Diastolic BP 85.2 Ϯ 11.7 80.8 Ϯ 12.9 .0185 controls. At the time of preparation of

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Table 3. Distribution of diabetic retinopathy and cataracts by centers for cases and controls: The AADM Study

Lagos Ibadan Enugu Accra Kumasi Total Diabetic retinopathy (Nϭ823) 44 (24%) 31 (20.9%) 25 (16%) 39 (23.5%) 8 (4.7%) 147 (17.9%) Males 22 (23.9%) 14 (16.7%) 13 (16.7%) 12 (15.4%) 2 (5.1%) 63 (18.1%) Females 22 (24.2%) 17 (26.6%) 12 (15.4%) 27 (24.3%) 6 (4.5%) 84 (17.7%) Cataracts Cases (Nϭ831) 103 (55.4%) 68 (46.3%) 62 (37.3%) 90 (54.2%) 50 (29.2%) 373 (44.9%) Males (Nϭ352) 48 (51.1%) 46 (55.4%) 32 (39.5%) 29 (52.7%) 12 (30.8%) 167 (47.4%) Females (Nϭ479) 55 (59.8%) 22 (34.4%) 30 (37.5%) 61 (55.0%) 38 (28.8%) 206 (43.0%) Controls (Nϭ191)* 9 (20.0%) 4 (14.8%) 4 (9.3%) 7 (21.9%) 11 (25.0%) 35 (18.3%) * Too few subjects to display detailed male/female distribution. tensive medication. While about 60% cataracts. Lagos and Accra, the largest were duration of diabetes, and FPG lev- of the hypertensive type 2 diabetes pa- urban centers in the 2 countries, had the el (Tables 5 and 6). Using logistic re- tients were on anti-hypertensive therapy, highest percentage of patients affected gression analysis, and the internal dis- only 27% of the hypertensive controls by diabetic retinopathy (24%). Similar- tribution of FPG levels, we grouped di- were on anti-hypertensive therapy. ly, the Lagos and Accra centers had the abetes subjects into 3 groups (Q1ϭ40– As shown in Table 3, the prevalence highest prevalence rate of cataracts (over 104.9 mg/dL; Q2ϭ105–243.9 mg/dL, of diabetic retinopathy was 17.9% 50%), with the city of Ibadan, the next and Q3ϭ244 mg/dL). We observed a across the 5 centers. Men had a slightly largest urban center, following closely, statistically significant association be- higher rate (18.1%) compared to wom- with a prevalence rate of 46.3%. The tween glucose levels and both retinopa- en (17.7%); however, this difference did urban and rural comparison was less thy and cataracts (Table 5). In compar- not have statistical significance. Among consistent for the controls, probably due ison to the patients in the group with subjects with diabetic retinopathy, 59% to small numbers. lowest FPG level, the risk of developing had the disease for 10 years or more, As shown in Table 4, diabetic reti- retinopathy was more than twice as high 24% for 5–9.9 years, and 17% for less nopathy and cataracts occurred more (ORϭ2.1; 95% CI, 1.2–3.8) for pa- than 5 years. Our data suggest that the frequently in patients who were older tients in the intermediate group, and left eye was more frequently affected by than 65 years. There was a steady in- more than 3 times as high for patients diabetic retinopathy, although this dis- crease in the prevalence of retinopathy in the group with the highest FPG level cordance did not reach statistical signif- and cataract with age. The observed in- (ORϭ3.4; 95% CI, 1.8–6.3). icance. In contrast, both eyes were crease in the prevalence of these 2 con- Similarly, we observed a clear trend equally affected by cataracts in cases and ditions was more dramatic for cataracts, between retinopathy, cataracts, and du- controls, in both genders, and across all however. For example, the prevalence of ration of diabetes (Table 6). The OR the age groups, in all 5 centers. cataracts in the Ͼ65-years age group comparing persons having diabetes for The prevalence of cataracts was was more than 10 times that of those in 10 years or more, to those having dia- 44.9% among patients with type 2 di- the 20–45-year age group (8.5% vs betes for less than 5 years, was 7.3 (95% abetes, compared to 18.3% among their 84.8%, respectively). The impact of age CI, 4.3–12.3) for retinopathy and 2.6 spouse controls, across the 5 centers on the prevalence of cataracts was also (95% CI, 1.7–4.0) for cataracts. Pa- (Table 3). No significant difference was strong among the control subjects. tients having diabetes from 5 to 9.9 observed between men (47.4.5%) and The 2 most important risk factors years had intermediate rates (ORϭ2.6 women (43.0%) in their rates of having for diabetic retinopathy in this cohort for retinopathy and 1.6 for cataracts).

Table 4. Distribution of diabetic retinopathy and cataracts by age groups and gender for persons with type 2 diabetes: The AADM Study

Diabetic Retinopathy Cataracts Age Groups N Males Females Total N Males Females Total 20–45 201 7 (9.6%) 17 (13.3%) 24 (11.9%) 201 5 (6.8%) 12 (9.4%) 17 (8.5%) 46–65 513 43 (18.9%) 56 (19.6%) 99 (19.3%) 518 121 (53.1%) 140 (49.1%) 261 (50.4%) Ͼ65 108 13 (27.1%) 11 (17.7%) 24 (21.8%) 112 41 (82.0%) 54 (87.1%) 95 (84.8%) Total 823 63 (18.1%) 84 (17.7%) 147 (17.9%) 831 167 (47.4%) 206 (43.0%) 373 (44.9%)

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Table 5. Distribution of odds ratios (OR) evaluating the association between the prevalence of retinopathy, cataracts, and fasting blood glucose level (FBG): The Despite a poor glycemic AADM Study control rate (more than 73% Diseases # of Persons FBG mg/dl OR (95% CI)* of patients had FPG levels Retinopathy 184 40–104.9 1.0 (reference) 373 105–243.9 2.1 (1.2–3.8) Ͼ126 mg/dL), the 190 ϭ244 3.4 (1.8–6.3) Cataracts 183 40–104.9 1.0 (reference) prevalence rate for diabetic 377 105–243.9 1.0 (0.7–1.6) 193 ϭ244 1.9 (1.2–3.1) retinopathy fell within the * Odds ratios were adjusted for age, sex, and BMI. lower range of reported estimates (9%–55%) for More than 50% of persons having type secutive diabetes patients examined in a 27–39 2 diabetes for 20 years exhibited reti- teaching hospital in Nigeria.42 In a Africa. nopathy, and nearly 70% had cataracts. South African rural district, diabetic retinopathy of any grade was found in 40.3% of patients, and due to the se- prevalence rate of diabetic retinopathy DISCUSSION verity of the condition, laser photoco- may be more representative of the gen- agulation was warranted in 11.1% of eral population in sub-Saharan Africa. 43 Using a standardized protocol in a the cases. However, in a larger study The major risk factors for diabetic multi-center study of the genetics of of 1,386 consecutively registered Ethi- retinopathy identiﬁed in this study in- type 2 diabetes in West Africans, we ob- opians with type 2 diabetes, Lester et al cluded sex, age, age at diagnosis, level of served the prevalences of diabetic reti- reported a prevalence of 15% for dia- glycemic control (FPG level), and du- nopathy and cataracts to be 17.9%, and betic retinopathy, which is closer to the ration of diabetes. Level of blood pres- 44.9%, respectively. The prevalence of prevalence observed in this West African sure exerted a small and independent 38 cataracts was estimated as 18.3% among cohort. risk to the prevalence of retinopathy in the spouse controls. Despite a poor gly- The wide range in prevalence esti- this cohort, after adjusting for the com- cemic control rate (more than 73% of mates across Africa is due to several rea- bined effects of age and sex in a logistic Ͼ patients had FPG levels 126 mg/dL), sons, including the use of hospital- model. The small effect of blood pres- the prevalence rate for diabetic retinop- based, as opposed to population-based, sure may be due to the relatively high athy fell within the lower range of re- patients. It is reasonable to expect that rate of hypertension treatment (60%) ported estimates (9%–55%) for Afri- studies based on hospital records will among type 2 diabetes patients; only 27–39 ca. have a preponderance of people with ad- 27% of the controls with diagnosed hy- In a study of 302 diabetic hospital vanced, and/or severe, disease; therefore, pertension were on anti-hypertensive patients in Ethiopia, Seyoum et al re- the rate of complications due to type 2 treatment, suggesting that diabetes pa- ported an overall prevalence of 37.8% diabetes will be over-represented. Due tients have a greater motivation to seek 41 for diabetic retinopathy. Nwosu et al to the scope and design of this study, medical attention, compared to individ- found a prevalence of 30% for visual which enrolled known, as well as new, uals with only hypertension. In addi- impairment in their study of 100 con- cases of type 2 diabetes, the estimated tion, given the real and perceived seri- ousness of the complications of diabetes, spouses may be more willing to divert Table 6. Distribution of odds ratios (OR) evaluating the association between the their often meager resources to the care prevalence of retinopathy, cataracts, and duration of diabetes: The AADM Study of their diabetic partners. Diseases # of Persons # with Disease Duration (years) OR (95% CI)* Unlike blood pressure, both dura- Retinopathy 368 25 0–4.9 1.0 (reference) tion of diabetes and level of glycemic 208 34 5–9.9 2.6 (1.5–4.5) control were major risk factors for dia- 230 85 10ϩ 7.3 (4.3–12.3) betic retinopathy. The odds ratio com- Cataracts 372 111 0–4.9 1.0 (reference) 210 98 5–9.9 1.6 (1.0–2.4) paring persons having diabetes for 10 232 155 10ϩ 2.6 (1.7–4.0) years or more, to persons having dia- * Odds ratios were adjusted for age, sex, and BMI. betes for less than 5 years, was 7.3 (95% CI, 4.3–12.3) for retinopathy, which is

S2-114 Ethnicity & Disease, Volume 13, Spring 2003 DIABETIC RETINOPATHY AND CATARACTS - Rotimi et al consistent with previous reports from ern, and the prevalence rates of diabetic of diabetic retinopathy to visual impair- several studies in both developed and retinopathy approximate the prevalence ment may approximate its contribution developing countries.38,44–48 reported in Western populations. It is to blindness in industrialized countries. The average duration of type 2 dia- plausible that this urban-rural gradient Currently, cataracts represent a greater betes in this population was about 7 exists because patients in the urban cen- visual impairment concern in West and years. The strong association observed ters had better health care, and survived Central Africa, and probably other parts between duration of diabetes and prev- long enough to develop retinopathy and of Africa, as well.62 Though type 2 di- alence of diabetic retinopathy clearly in- be examined, while rural patients with abetes contributed significantly to the dicates that the level of glycemic control no health care died before developing development of cataracts in this popu- in this cohort was, indeed, poor; about retinopathy, or did not survive long lation, the high prevalence of cataracts 60% of patients having the disease for enough with their retinopathy to be in the control population demonstrates 10 years or more also had some form of available for examination. This is a that other cataractogenic factors, unre- retinopathy, compared to 17% of those known issue in epidemiology, hence the lated to type 2 diabetes, play an impor- having the disease for less than 5 years. expressed: PϭIn*D; where Pϭprev- tant role in the development of cata- Similarly, patients with the worst level alence, Inϭincidence, and Dϭduration racts. of glycemic control had more than 3 of diseases.57 This study provided compelling ev- times the risk of developing type 2 di- Worldwide, 50% of all cases of di- idence that developing strategies for diabetes, compared to those with the abetes remain undiagnosed.58 The rate abetes prevention, glycemic control, and ‘‘best’’ control in this cohort. of undiagnosed diabetes in sub-Saharan early/regular eye examination, would re- A consistent association between Africa may be higher than 50%. Con- duce the impact of diabetes on vision. poor glycemic control and diabetic ret- sequently, when the frequency of screen- In addition, investment in the relatively inopathy has been described in several ing for type 2 diabetes increases, and inexpensive surgical treatment of cata- populations.49–53 The Diabetes Control better technology for ocular examina- racts in West Africa would improve the and Complications Trial (DCCT) dem- tion is used, the prevalence of reported quality of life for people with ocular onstrated, in a large cohort of patients diabetic retinopathy in Africa may be complications. with type 1 diabetes, the importance of significantly higher, probably approach- REFERENCES hyperglycemia as a major risk factor for ing estimates from industrialized coun- 1. Palmberg PF. Diabetic retinopathy. Diabetes. diabetic microvascular complications, tries. 1977;26:703–709. including retinopathy, neuropathy, and The most effective method for the 2. Retinopathy Working Party. A protocol for nephropathy.54 The results of the United treatment of diabetic retinopathy, and screening for diabetic retinopathy in Europe. Diabet Med. 1991;8:263–267. Kingdom Prospective Diabetes Study prevention of the new blood vessel for- 3. Harris MI, Klein R, Welborn TA, Knuiman (UKPDS) also demonstrated that tight mation that ultimately leads to blind- MW. Onset of NIDDM occurs at least 4–7 glycemic control, with any of several ness, is photocoagulation.59,60 Vision years before clinical diagnosis. Diabetes Care. therapeutic regimens, would significant- may also be restored with the time-con- 1992;15:815–819. 4. Jarrett Jr. Duration of non-insulin-dependent ly reduce the risk for long-term micro- suming and expensive vitrectomy. Re- diabetes and development of retinopathy: vascular complications of type 2 diabe- sults from Sweden clearly demonstrate analysis of possible risk factors. 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The Wisconsin Epidemiologic both diabetic retinopathy and cataracts. blindness in the future. Study of Diabetic Retinopathy. II. Prevalence In these cities, the lifestyle is more West- In the long term, the contribution and risk of diabetic retinopathy when age at

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diagnosis is less than 30 years. Arch Ophthal- SP. Incidence of and risk factors for diabetic degree of control. East Afr Med J. 1989;66: mol. 1984;102:520–526. retinopathy in diabetic clinic attenders. 248–254. 9. Klein BEK, Moss SE, Klein R. Is menarche Ophthalmol Epidemiol. 2001;8(5):309–325. 38. Lester FT. Clinical features, complications, associated with diabetic retinopathy? Diabetes 24. Lewallen S, Courtright P. Blindness in Africa: and mortality in type 2 (non-insulin depen- Care. 1990;13:1034–1038. present situation and future needs. Br J dent) diabetic patients in Addis Ababa, Ethi- 10. Murphy RP, Nanda M, Plotnick L, Enger C, Ophthalmol. 2001;85:897–903. opia. Ethiop Med J. 1993;31:109–126. Vitale S, Patz A. The relationship of puberty 25. King H, Aubert RE, Herman WH. Global 39. Rotimi CN, Dunston GM, Berg K, et al. In to diabetic retinopathy. Arch Ophthalmol. burden of diabetes, 1995–2025: prevalence, search of susceptibility genes for type 2 dia- 1990;108:215–218. numerical estimates, and projections. Diabetes betes in West Africa: the design and results of 11. Klein BEK, Moss SE, Klein R. Effect of preg- Care. 1998;21:1414–1431. the ﬁrst phase of the AADM Study. Ann Ep- nancy on progression of diabetic retinopathy. 26. Ikem RT, Akinola NO, Balogun MO, Ohwo- idemiol. 2001;11:51–58. Diabetes Care. 1990;13:34–40. voriole AE, Akinsola A. What does the pres- 40. American Diabetes Association. Screening for 12. Rodman HM, Singerman LJ, Aiello LM, ence of hypertension portend in the Nigerian type 2 diabetes. Diabetes Care. 1992;22(suppl Merkatz IR. Diabetic retinopathy and its re- with non insulin dependent diabetes mellitus. 1):S20–S23. lationship to pregnancy. In: Merkatz IR, Ad- West Afr J Med. 2001;20(2):127–130. 41. Seyoum B, Mengitsu Z, Berhanu P, et al. Ret- ams PAJ, eds. The Diabetic Pregnancy: A Peri- 27. Neuhann HF, Water-Neuhann C, Lyaruu I, inopathy in patients of Tikur Anbessa Hos- natal Perspective. New York, NY: Grune and Msuya L. Diabetes care in Kilimanjaro re- pital diabetic clinic. Ethiop Med J. 2001;39: Stratton; 1979. gion: clinical presentation and problems of 123–131. 13. Klein R, Klein BEK, Moss SE, Davis MD, patients of the diabetes clinic at the regional 42. Nwosu SN. Low vision in Nigerians with di- DeMets DL. The Wisconsin Epidemiologic referral hospital—an inventory before struc- abetes mellitus. Doc Ophthalmol. 2000; Study of Diabetic Retinopathy. X. Four-year tured intervention. Diabet Med. 2002;19(6): 101(1):51–57. incidence and progression of diabetic retinop- 509–513. 43. Rotchford AP, Rotchford KM. Diabetes in ru- athy when age at diagnosis is less than 30 28. Drabo PY, Kabore J, Lengani A. Complica- ral South Africa—an assessment of care and years. Arch Ophthalmol. 1989;107:244–249. tions of diabetes mellitus at the Hospital Cen- complications. S Afr Med J. 2002;92(7):536– 14. Klein R, Klein BEK, Moss SE, Cruickshanks ter of Ouagadougou. Bull Soc Pathol Exot. 541. KJC. The Wisconsin Epidemiologic Study of 1996;89:191–195. 44. Porta M, Tomalino MG, Santoro F, et al. Di- Diabetic Retinopathy. XIV. Ten-year inci- 29. Gebre-Yohannes A, Rahlenbeck SI. Glycemic abetic retinopathy as a cause of blindness in dence and progression of diabetic retinopathy. control and its determinants in diabetic pa- the province of Turin, north-west Italy, in Arch Ophthalmol. 1994;112:1217–1228. tients in Ethiopia. Diabetes Res Clin Pract. 1987–1991. Diabet Med. 1995;12:355–361. 15. Mokdad AH, Ford ES, Bowman BA, et al. 1997;35:129–134. 45. Osuntokun BO. Diabetic retinopathy in Ni- Diabetes trends in the US, 1990–1998. Di- 30. Sidibe EH. Diabetic retinopathy in Dakar gerians. A study of 758 patients. Br J abetes Care. 2000;23:1278–1283. and African literature review: epidemiologic Ophthalmol. 1969;53(10):652–663. 16. Ballard DJ, Melton LJ, Dwyer MS, Traut- elements. Diabetes Metab. 2000;26(4):322– 46. Levin L, Gelfand M. Diabetic retinopathy in mann JC, O’Fallon WM, Palumbo PJ. Risk 324. African patients. S Afr Med J. 1973;47:993– factors for diabetic retinopathy: a population- 31. Osuntokun BO, Akinkugbe FM, Francis TI, 994. based study in Rochester, Minnesota. Diabetes Reddy S, Osuntokun O, Taylor GO. Diabe- 47. Klein R, Klein BEK, Scott EM. The Wiscon- Care. 1986;9:334–342. tes mellitus in Nigerians: a study of 832 pa- 17. Nelson RG, Newman JM, Knowler WC, et tients. West Afr Med J Niger Pract. 1971;20: sin Epidemiologic Study of Diabetic Retinop- al. Incidence of end-stage renal disease in type 295–312. athy. XVI. The relationship of C-peptide to 2 (non-insulin-dependent) diabetes mellitus 32. Sobngwi E, Mbanya JC, Moukouri EN, et al. the incidence and progression of diabetic ret- in Pima Indians. Diabetologia. 1988;31:730– Microalbuminuria and retinopathy in a dia- inopathy. 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Henricsson M, Nystrom L, Blohme G, et al. Res Clin Pract. 1995;30:59–67. epidemiology of diabetes complications study. The incidence of retinopathy 10 years after 36. Kaimbo DK, Kabongo DK, Missotten L. Oc- IV. Correlates of diabetic background and diagnosis in young adult people with diabetes. ular complications in diabetes mellitus in proliferative retinopathy. Am J Epidemiol. Diabetes Care. 2003;26:349–354. Zaire. Bull Soc Belge Ophtalmol. 1995;255: 1991;133:381–391. 22. Klein BEK, Moss SE, Klein R. Longitudinal 107–113. 53. The Diabetes Control and Complications Tri- measure of glycemic control and diabetic ret- 37. Erasmus RT, Alanamu RA, Bojuwoye B, et al. al Research Group. The effect of intensive inopathy. Diabetes Care. 1987;10:273–277. Diabetic retinopathy in Nigerians: relation to treatment of diabetes on the development and 23. Janghorbani M, Jones RB, Murray KJ, Allison duration of diabetes, type of treatment, and progression of long term complications in the

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