It has been shown that subjects with normal glucose tolerance (NGT) but elevated 1-hour glucose level ≧155 mg/dl during a 75g oral glucose tolerance test (75g OGTT) is an independent risk factor for type 2 diabetes. In Caucasian, subjects with elevated 1-h glucose were characterized by adiposity with lower insulin sensitivity and impaired beta-cell function. While type 2 diabetes in Asians is frequently affected in non-obese (BMI<25 kg/m2) subjects, the characteristics of non-obese Asians with elevated 1-h glucose are totally unknown. Here, we studied 59 non-obese Japanese men with NGT. Based on the level of 1-hour glucose level during 75g OGTT, we divided the subjects into Low-1 hour group (< 155mg/dl) and High-1 hour group (≧155mg/dl). We measured ectopic fat in muscle and liver and subcutaneous and viscera fat areas by 1H-MRS and MRI, respectively. We also measured tissue specific insulin sensitivity by 2 step hyperinsulinemic-euglycemic clamp. Insulinogenic index (0.66±0.30 vs. 1.41±1.21ΔInsulin0-30 min/ΔGlucose 0-30min, p=0.02) was significantly lower and area under the curve of glucose and insulin during 75g OGTT were significantly higher in High-1 hour group than Low-1 hour group (Figure). However, other parameters including insulin sensitivity and ectopic fat in muscle and liver, subcutaneous and viscera fat areas were comparable between the groups. These data suggest that non-obese Japanese men with High-1 hour glucose are characterized by impaired early-phase insulin secretion and subsequent hyperinsulinemia. Insulin resistance and abnormal fat distribution are not evident in this population.
M. Sato: None. Y. Tamura: None. H. Kaga: None. Y. Someya: None. S. Kakehi: None. N. Yamasaki: None. D. Sugimoto: None. S. Kadowaki: None. R. Suzuki: None. Y. Furukawa: None. K. Takeno: None. T. Funayama: None. R. Kawamori: None. H. Watada: Research Support; Self; Astellas Pharma Inc., Boehringer Ingelheim Pharmaceuticals, Inc., Daiichi Sankyo Company, Limited, Kissei Pharmaceutical Co., Ltd., Merck Sharp & Dohme Corp., Mitsubishi Tanabe Pharma Corporation, Novartis Pharmaceuticals Corporation, Novo Nordisk A/S, Pfizer Inc., Sanofi, Sumitomo Dainippon Pharma Co., Ltd., Takeda Pharmaceutical Company Limited, Teijin Pharma Limited. Speaker's Bureau; Self; Astellas Pharma Inc., Boehringer Ingelheim Pharmaceuticals, Inc., Daiichi Sankyo Company, Limited, Eli Lilly and Company, Merck Sharp & Dohme Corp., Mitsubishi Tanabe Pharma Corporation, Novo Nordisk A/S, Ono Pharmaceutical Co., Ltd., Sanofi, Takeda Pharmaceutical Company Limited, Terumo Medical Corporation. Other Relationship; Self; Boehringer Ingelheim Pharmaceuticals, Inc., Kowa Pharmaceutical Europe Co. Ltd., Merck Sharp & Dohme Corp., Mitsubishi Tanabe Pharma Corporation, Ono Pharmaceutical Co., Ltd., Sanwa Chemical Industry Co. Ltd., Takeda Pharmaceutical Company Limited.