1521-P: Healthy, Nonobese South Asian Men Have Both Greater Peripheral and Hepatic Insulin Resistance than Chinese Men

Introduction: South Asian individuals, despite a healthy weight, are at a greater risk of type 2 diabetes mellitus than Chinese individuals. This may be secondary to higher peripheral and/or hepatic insulin resistance (IR). Using the 2-stepped hyperinsulinemic-euglycemic clamp, we examined the differences in peripheral and hepatic insulin resistance between healthy and non-obese South Asian and Chinese men. Bioimpedance analysis was performed to assess body composition.

Methods: A 2-stepped hyperinsulinemic-euglycemic clamp was performed together with a “pancreatic” clamp by infusing somatostatin. A low-dose insulin (10 mU/m²/min) was infused for 2 hours, followed by high-dose insulin infusion (40 mU/m²/min) for 2 hours. Intravenous 20% glucose was infused to maintain euglycemia (blood glucose = 95-100 mg/dl) for the clamp duration. A higher M value (mg glucose per kg bodyweight per minute) during low-dose insulin infusion reflects lower hepatic IR while a higher M value during high-dose insulin infusion reflects lower peripheral IR.

Results: The 2 groups (26 South Asian and 26 Chinese men) had similar age (27.3 vs 26.2 years, p = 0.338), but the South Asian group had slightly higher BMI (24.6 vs 22.9 kg/m², p = 0.027) and body fat % (23.9 vs. 20.6%, p < 0.05). During low-dose step, the M-value was lower among South Asians compared to Chinese (0.8 ± 0.58 vs. 1.1 ± 0.55 mg/kg/min, p = 0.027). During high-dose step, the M-value was also lower among South Asians compared to Chinese (3.2 ± 2.6 vs. 5.2 ± 3.3 mg/kg/min, p = 0.015). The differences in the M-values between South Asian and Chinese individuals remained significant after correcting for body weight and fat-free mass.

Conclusion: Despite a healthy weight, young South Asians have both greater hepatic and peripheral muscle IR than Chinese.