Increased Intramyocellular Lipid Concentration Identifies Impaired Glucose Metabolism in Women With Previous Gestational Diabetes Alexandra Kautzky-Willer,1 Martin Krssak,1 Christine Winzer,1 Giovanni Pacini,2 Andrea Tura,2 Serdar Farhan,1 Oswald Wagner,3 Georg Brabant,4 Ru¨ diger Horn,4 Harald Stingl,1 Barbara Schneider,5 Werner Waldha¨usl,1 and Michael Roden1 Women with previous gestational diabetes (pGDM) are frequently insulin-resistant, which could relate to in- tramyocellular lipid content (IMCL). IMCL were mea- estational diabetes mellitus (GDM) is a fre- sured with 1H nuclear magnetic resonance spectroscopy quent metabolic complication during preg- in soleus (IMCL-S) and tibialis-anterior muscles nancy that does not completely normalize after -IMCL-T) of 39 pGDM (32 ؎ 2 years, waist-to-hip ratio Gdelivery (1–3). Women with a history of previ) -and 22 women with normal glucose toler- ous gestational diabetes (pGDM) are often insulin-resis (0.01 ؎ 0.81 ance (NGT; 31 ؎ 1 years, 0.76 ؎ 0.02) at 4–6 months tant and exhibit markedly increased risk for the later after delivery. Body fat mass (BFM) was assessed from development of type 2 diabetes (4,5). The most prominent bioimpedance analysis, insulin sensitivity index (SI), parameters that predict type 2 diabetes in later life are the and glucose effectiveness (SG) from insulin-modified need for insulin in addition to diet therapy to achieve frequently sampled glucose tolerance tests. pGDM ex- normoglycemia, early diagnosis of GDM during pregnancy, hibited 45% increased BFM, 35% reduced SI and SG (P < and maternal BMI and plasma glucose during the oral 0.05), and 40% (P < 0.05) and 55% (P < 0.005) higher glucose tolerance test (OGTT) at diagnosis as well as at IMCL-S and IMCL-T, respectively. IMCL related to body the first postpartum assessment (4,6,7). fat (BFM P < 0.005, leptin P < 0.03), but only IMCL-T Skeletal muscle insulin resistance is a key feature of the correlated (P < 0.03) with SI and glucose tolerance metabolic syndrome and predisposes to type 2 diabetes ؍ index independent of BMI. Insulin-resistant pGDM (n and premature cardiovascular complications (8). Although (had higher IMCL-S (؉66%) and IMCL-T (؉86% (17 lifestyle (9), obesity, and increased lipid supply play an than NGT and insulin-sensitive pGDM (؉28%). IMCL important role in this disease (8,10), the hierarchy of -in insulin (0.05 ؍ were also higher (P < 0.005, P sensitive pGDM requiring insulin treatment during events is still unclear. It was postulated that muscle fat content could contribute to insulin resistance and glucose pregnancy and inversely related to the gestational week 1 of GDM diagnosis. Thus, IMCL-T reflects insulin sensi- intolerance (11–19), but only the advent of H nuclear tivity, whereas IMCL-S relates to obesity. IMCL could magnetic resonance spectroscopy (NMRS) made it possi- serve as an additional parameter of increased diabetes ble to quantify and distinguish between extramyocellular risk because it identifies insulin-resistant pGDM and and intramyocellular lipid contents (IMCL) (11,14,15,17, those who were diagnosed earlier and/or required insu- 18,20–22). lin during pregnancy. Diabetes 52:244–251, 2003 We tested the hypotheses that intracellular fat content in different muscles diversely relates to insulin sensitivity and correlates with established risk markers for type 2 diabetes in pGDM, such as gestational week at diagnosis, insulin treatment during pregnancy, glucose levels during From the 1Department of Internal Medicine III, Division of Endocrinology and OGTT at diagnosis and postpartum, and the degree of Metabolism, University of Vienna, Vienna, Austria; 2Metabolic Unit, Institute 1 of Biomedical Engineering, National Research Council (ISIB-CNR), Padova, obesity. Thus, we applied H NMRS to measure rapidly and Italy; 3Institute for Medical Laboratory Diagnostics, University of Vienna, noninvasively IMCL in soleus (IMCL-S) and tibialis ante- Vienna, Austria; 4Division of Endocrinology, University of Hannover, Han- rior muscles (IMCL-T) in pGDM. IMCL were correlated nover, Germany; and 5Institute of Biostatistics, University of Vienna, Vienna, Austria. with parameters of glucose tolerance, insulin sensitivity, Address correspondence and reprint requests to Michael Roden, MD, cardiovascular risk, body fat content, and distribution. Division of Endocrinology and Metabolism, Department of Internal Medicine Furthermore, the study extends to potential links between III, University of Vienna, Wa¨hringer Gu¨ rtel 18-20, A-1090, Vienna, Austria. E-mail: [email protected]. IMCL and the leptin system, which participates in the Received for publication 25 June 2002 and accepted in revised form 16 regulation of body weight (BW) and energy metabolism October 2002. AIRg 3–10, acute insulin response 3–10 min after glucose ingestion; BFM, (19,23,25,26). body fat mass; BW, body weight; FFM, fat-free mass; GDM, gestational diabetes mellitus; IMCL, intramyocellular lipid content; IMCL-S, IMCL of soleus muscle; IMCL-T, IMCL of tibialis anterior; NGT, normal glucose RESEARCH DESIGN AND METHODS tolerance; NMRS, nuclear magnetic resonance spectroscopy; OGIS, insulin sensitivity parameter; OGTT, oral glucose tolerance test; pGDM, previous All women ingested an isocaloric diet containing 200 g of carbohydrates/day gestational diabetes mellitus; SI, insulin sensitivity index. and refrained from exercise for at least 3 days before the studies. Metabolic 244 DIABETES, VOL. 52, FEBRUARY 2003 A. KAUTZKY-WILLER AND ASSOCIATES TABLE 1 Clinical characteristics of the total group of women with pGDM (n ϭ 39), the insulin-resistant subgroup (GDM-R, n ϭ 17), and the insulin-sensitive subgroup (GDM-S, n ϭ 22) compared with women with NGT during pregnancy (n ϭ 23) 4–6 months after delivery GDM GDM-R GDM-S NGT Age (years) 31.1 Ϯ 0.81 31.0 Ϯ 1.4 31.2 Ϯ 1.0 30.6 Ϯ 1.3 BMI (kg/m2) 26.4 Ϯ 1.1 29.8 Ϯ 1.8 24.9 Ϯ 0.8* 24.3 Ϯ 0.9† WHR 0.81 Ϯ 0.01 0.81 Ϯ 0.01 0.80 Ϯ 0.01 0.76 Ϯ 0.02 Waist (cm) 89.1 Ϯ 2.3§ 96.1 Ϯ 2.5 84.5 Ϯ 2.2* 75.1 Ϯ 2.3†‡ Triglycerides (mg/dl) 118.2 Ϯ 22.0 136.3 Ϯ 50.9 105.9 Ϯ 14.3 75.2 Ϯ 6.3 Cholesterol (mg/dl) 210.9 Ϯ 7.6 200.3 Ϯ 14.1 218.0 Ϯ 8.3 198.0 Ϯ 12.4 HDL cholesterol (mg/dl) 61.4 Ϯ 2.7 54.8 Ϯ 4.7 65.8 Ϯ 3.9* 62.1 Ϯ 2.9† LDL cholesterol (mg/dl) 126.2 Ϯ 6.5 118.9 Ϯ 10.9 131.2 Ϯ 7.9 120.8 Ϯ 11.0 Systolic blood pressure (mmHg) 116.7 Ϯ 2.2 123.7 Ϯ 3.9 112.3 Ϯ 2.3* 111.5 Ϯ 2.6† Diastolic blood pressure (mmHg) 80.0 Ϯ 1.5§ 83.0 Ϯ 2.5 78.1 Ϯ 1.9 74.1 Ϯ 1.9† Ϯ Ϯ Ϯ Ϯ HbA1c (%) 5.40 0.07§ 5.36 0.14 5.43 0.08 5.1 0.03† Basal metabolic rate (kJ/kg BW) 20.10 Ϯ 0.55§ 18.35 Ϯ 0.69 21.75 Ϯ 0.65* 22.03 Ϯ 0.51† Basal metabolic rate (kJ/kg FFM) 30.50 Ϯ 0.33 29.35 Ϯ 0.50 31.58 Ϯ 0.42* 30.57 Ϯ 0.39† *P Ͻ 0.05 GDM-R versus GDM-S; †P Ͻ 0.05 GDM-R versus NGT; ‡P Ͻ 0.05 GDM-S versus NGT; §P Ͻ 0.05 GDM versus NGT. tests were performed on different days during the first phase (days 5–8) of the sensitivity from OGTT (OGIS) was derived as glucose clearance (ml ⅐ minϪ1 ⅐ menstrual cycle after 10- to 12-h overnight fasting. mϪ2) (31). Study participants. Cross-sectional analysis was performed in 39 pGDM Localized 1H NMRS. IMCL was measured with localized 1H NMRS (17,20,21) women at 4–6 months after delivery. They were recruited from our division’s on a 3.0-T/80-cm NMR spectrometer (Medspec; Bruker, Ettlingen, FRG) outpatient service, where they had been seen previously during pregnancy. equipped with a whole-body gradient coil (40 mT/m; Fig. 1). A standard GDM had been diagnosed according to the criteria of the 4th Workshop birdcage 1H coil (inner diameter 25 cm) was used in the transmission/ Conference of Gestational Diabetes (27). During pregnancy, 26 women were reception mode. The STEAM sequence (echo time 20 ms; mixing time 30 ms; treated with diet plus insulin, because blood glucose exceeded 95 mg/dl at relaxation time 6 s; number of scans 32) was complemented by CHESS water fasting and/or 130 mg/dl at 60 min postprandially. A total of 22 age-matched suppression and applied on the 1.73-cm3 volume of interest, which was placed women without any risk for diabetes and with normal glucose tolerance in the soleus or tibialis anterior muscles of the subject’s right leg. Spectra were during pregnancy served as a control group (NGT). All subjects gave written line-broadened and -fitted using the MacNUTS-PPC software (Acorn NMR, informed consent for participation in the study, which was approved by the Livermore, CA). IMCL was quantified from processed spectra after T2- local ethics committee. relaxation correction as a ratio of the intensity of (CH2)n (1.25 ppm) group Patients with previous ketoacidosis and/or ␤-cell antibodies (GAD, ICA, resonance to the intensity of the water resonance from non–water-suppressed IA2) were excluded. The relationship among IMCL, insulin sensitivity, and spectra of the same volume of interest (Fig. 1).