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Objective: To examine whether the patterns of insulin concentration during the oral glucose tolerance test (OGTT) predict type 2 diabetes., Research Design and Methods: We followed 400 nondiabetic Japanese Americans for 10-11 years. Insulin concentrations at 30, 60, and 120 min during a 2-h 75-g OGTT at baseline were used to derive the following possible patterns of insulin: pattern 1 (30-min peak, higher insulin level at 60 than at 120 min), pattern 2 (30-min peak, lower or equal level at 60 vs. 120 min), pattern 3 (60-min peak); pattern 4 (120-min peak, lower level at 30 than at 60 min), and pattern 5 (120-min peak, equal or higher level at 30 vs. 60 min). Insulin sensitivity was estimated by homeostasis model assessment of insulin resistance (HOMA-IR) and Matsuda index. Insulin secretion was estimated by the insulinogenic index (IGI) [Δinsulin/Δglucose (30-0 min)] and disposition index (IGI/HOMA-IR)., Results: There were 86 incident cases of type 2 diabetes. The cumulative incidence was 3.2, 9.8, 15.4, 47.8, and 37.5% for patterns 1, 2, 3, 4, and 5, respectively. Compared with pattern 1, patterns 4 and 5, characterized by a lasting late insulin response, were associated with significantly less insulin sensitivity as measured by the Matsuda index and lower early insulin response by the disposition index. The multiple-adjusted odds ratios of type 2 diabetes were 12.55 (95% CI 4.79-32.89) for pattern 4 and 8.34 (2.38-29.27) for pattern 5 compared with patterns 1 and 2. This association was independent of insulin secretion and sensitivity., Conclusions: The patterns of insulin concentration during an OGTT strongly predict the development of type 2 diabetes.

Migrant Japanese populations in both the USA and Brazil have for a long time shown a higher prevalence of type 2 diabetes than native Japanese, suggesting an interaction of lifestyle and genetic predisposition in the etiology of type 2 diabetes. The overall objective of the Seattle Japanese American Community Diabetes Study was to learn more about the etiology and pathogenesis of type 2 diabetes in Japanese Americans. This metabolically based epidemiological study included extensive assessments of insulin sensitivity, insulin response, and adiposity with the latter including measurements of body fat distribution by both anthropometry and computed tomography. Because of this, the importance of visceral adiposity as a risk factor for abnormal glucose tolerance, hypertension, coronary heart disease and the metabolic syndrome was shown. In conjunction with an examination of diet and physical activity patterns, the result was a clearer understanding of the etiology and pathogenesis of type 2 diabetes in Japanese Americans. We propose that a lifestyle that fosters increased weight gain, especially in the visceral adipose depot, promotes the development of insulin resistance, which in turn exposes an underlying reduced β-cell reserve in susceptible individuals, resulting in glucose intolerance and, eventually in many, the development of diabetes. We have shown that it might be possible to delay or prevent the development of diabetes through dietary and exercise interventions in individuals identified as having impaired glucose tolerance. The lessons learned from studying migrant Japanese in Seattle might in many ways be applicable to other populations of Asian origin. (J Diabetes Invest, doi: 10.1111/j.2040-1124.2012.00195.x, 2012) [ABSTRACT FROM AUTHOR]

OBJECTIVE--It has been reported that moderate alcohol consumption decreased the risk of type 2 diabetes but that elevated liver enzymes increased it. The comparative importance of alcohol consumption and liver enzymes as predictors of type 2 diabetes remains unconfirmed. RESEARCH DESIGN AND METHODS--The participants included 8,576 Japanese men, aged 40-55 years, without type 2 diabetes at entry. Type 2 diabetes was diagnosed if a fasting plasma glucose level was ≥126 mg/dl or if participants were taking oral hypoglycemic medications or insulin. RESULTS--During the 4-year follow-up period, we confirmed 878 cases. In multivariate models, moderate daily alcohol consumption (16.4-42.6 g ethanol/day) decreased the risk of type 2 diabetes, and higher levels of γ-glutamyhransferase (GGT) and alanine aminotransferase (ALT) increased the risk. In joint analyses of alcohol consumption and liver enzymes, moderate drinkers with the lowest tertile of GGT had the lowest risk of type 2 diabetes. Compared with them, nondrinkers with the highest GGT had the highest risk of type 2 diabetes (odds ratio 3.18 [95% CI 1.75-5.76]). At every level of GGT, moderate or heavy alcohol drinkers (≥42.7 g ethanol/day) had a lower risk of type 2 diabetes than nondrinkers. The relationship of ALT and daily alcohol consumption with the risk of type 2 diabetes was almost the same as that of GGT. CONCLUSIONS--GGT, ALT, and daily alcohol consumption were independently associated with the risk of type 2 diabetes. Nondrinkers with the highest GGT or ALT had a high risk of type 2 diabetes. [ABSTRACT FROM AUTHOR]

OBJECTIVE--Visceral adiposity is generally considered to play a key role in the metabolic syndrome. We sought to determine whether greater visceral adiposity directly measured by computed tomography (CT) is associated with increased future insulin resistance independent of other adipose depots. RESEARCH DESIGN AND METHODS--We followed 306 nondiabetic Japanese Americans over 10-11 years. Baseline variables included BMI; waist circumference; and abdominal, thoracic, and thigh fat areas measured by CT. Total fat area was estimated by the sum of all of these fat areas. Visceral adiposity was measured as intra-abdominal fat area at the umbilicus level. Total subcutaneous fat area was defined as total fat area minus intra-abdominal fat area. Insulin resistance was evaluated by homeostasis model assessment for insulin resistance (HOMA-IR), fasting plasma insulin level, Matsuda index, and area under the oral glucose tolerance test curve (AUC) of insulin. RESULTS--Both baseline intra-abdominal fat area (P = 0.002) and HOMA-IR (P < 0.001) were independently associated with increased HOMA-IR at 10-11 years in a multiple linear regression model after adjustment for abdominal subcutaneous fat area, age, sex, 2-h plasma glucose level, and incremental insulin response. Intra-abdominal fat area remained a significant predictor of increased HOMA-IR at 10-11 years even after adjustment for total subcutaneous fat area, total fat area, BMI, or waist circumference, but no other measure of CT-measured regional or total adiposity was significantly related with HOMA-IR at 10-11 years in models that contained intra-abdominal fat area. Similar results were obtained for predicting future fasting plasma insulin level, Matsuda index, and AUC of insulin. CONCLUSIONS--Greater visceral adiposity is associated with an increase in future insulin resistance. [ABSTRACT FROM AUTHOR]

OBJECTIVE -- Because skeletal muscle is one of the target tissues for insulin, skeletal muscle mass might be associated with type 2 diabetes. Serum creatinine is a possible surrogate marker of skeletal muscle mass. The purpose of this study was to determine whether serum creatinine level is associated with type 2 diabetes. RESEARCH DESIGN AND METHODS-- The study participants were nondiabetic Japanese men (n = 8,570) aged 40-55 years at entry. Type 2 diabetes was diagnosed if fasting plasma glucose was ≥ 126 mg/dl or if participants were taking oral hypoglycemic medication or insulin. RESULTS-- During the 4-year follow-up period, 877 men developed type 2 diabetes. Lower serum creatinine was associated with an increased risk of type 2 diabetes. The multiple-adjusted odds ratio for those who had serum creatinine levels between 0.40 and 0.60 mg/dl was 1.91 (95% CI 1.44-2.54) compared with those who had levels between 0.71 and 0.80 mg/dl. CONCLUSIONS -- Lower serum creatinine increased the risk of type 2 diabetes. [ABSTRACT FROM AUTHOR]