Visceral adiposity and risk of type 2 diabetes - A prospective study amongJapanese Americans

OBJECTIVE - We conducted a prospective study among Japanese Americans of di abetes incidence in relation to visceral and regional adiposity, fasting in sulin and C-peptide, and a measure of insulin secretion, because little pro spective data exist on these associations. RESEARCH DESIGN AND METHODS - Baseline variables included plasma glucose, C -peptide, and insulin measured after an overnight fast and 30 and 120 min a fter a 75-g oral glucose tolerance test; abdominal, thoracic, and thigh fat areas by computed tomography (CT); BMI (kg/m(2)); and insulin secretion (i ncremental insulin response [IIR]). RESULTS - Study subjects included 290 second-generation (nisei) and 230 thi rd-generation (sansei) Japanese Americans without diabetes, of whom 65 and 13, respectively, developed diabetes. Among nisei, significant predictors o f diabetes risk for a 1 SD increase in continuous variables included intra- abdominal fat area (IAFA) (odds ratio, 95% CI) (1.6, 1.1-2.3), fasting plas ma C-peptide (1.4, 1.1-1.8), and the IIR (0.5, 0.3-0.9) after adjusting for age, sex, impaired glucose tolerance, family diabetes history, and CT-meas ured fat areas other than intraabdominal. Intra-abdominal fat area remained a significant predictor of diabetes incidence even after adjustment for BM I, total body fat area, and subcutaneous fat area, although no measure of r egional or total adiposity was related to development of diabetes. Among sa nsei, all adiposity measures were related to diabetes incidence, but, in ad justed models, only IAFA remained significantly associated with higher risk (2.7, 1.4-5.4, BMI-adjusted). CONCLUSIONS - Greater visceral adiposity precedes the development of type 2 diabetes in Japanese Americans and demonstrates an effect independent of f asting insulin, insulin secretion, glycemia, total and regional adiposity, and family history of diabetes.