Insulin, C-Peptide, and Leptin Concentrations Predict Increased Visceral Adiposity at 5- and 10-Year Follow-Ups in Nondiabetic Japanese Americans

Insulin, C-Peptide, and Leptin Concentrations Predict Increased Visceral Adiposity at 5- and 10-Year Follow-Ups in Nondiabetic Japanese Americans Jenny Tong 1 , Wilfred Y. Fujimoto 1 , Steven E. Kahn 1 , David S. Weigle 1 , Marguerite J. McNeely 2 , Donna L. Leonetti 3 , Jane B. Shofer 4 and Edward J. Boyko 5 1 Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, VA Puget Sound Health Care System and Harborview Medical Center, University of Washington, Seattle, Washington 2 Department of Medicine, University of Washington, Seattle, Washington 3 Department of Anthropology, University of Washington, Seattle, Washington 4 Research and Development Service, VA Puget Sound Health Care System, Seattle, Washington 5 Epidemiologic Research and Information Center, VA Puget Sound Health Care System, Seattle, Washington Address correspondence and reprint requests to Jenny Tong, MD, VA Puget Sound (S-151), 1660 S. Columbian Way, Seattle, WA 98108. E-mail: tongj{at}u.washington.edu Abstract We prospectively examined the relationship between leptin and markers of insulin resistance and secretion and future visceral adipose tissue accumulation. In this study, 518 nondiabetic Japanese-American men and women underwent the following measurements at baseline and at 5- and 10-year follow-ups: plasma glucose and insulin measured after an overnight fast and during a 75-g oral glucose tolerance test, insulin secretion ratio (ISR) [(30-min insulin − fasting insulin)/30-min glucose], fasting C-peptide levels, plasma leptin (baseline only), and fat areas (intra-abdominal and subcutaneous) measured by computed tomography. Predictors of future intra-abdominal fat (IAF) were determined using multiple linear regression. Fasting insulin and C-peptide levels at baseline were significantly associated with IAF area at 5 years (coefficient = 0.041, P = 0.001 and coefficient = 1.283, P < 0.001, respectively) and 10 years (coefficient = 0.031, P = 0.020 and coefficient = 0.221, P = 0.035, respectively). ISR was not significantly associated with IAF at 5 or 10 years. Leptin level at baseline was positively associated with IAF at 5 years (coefficient = 0.055, P = 0.002) and 10 years (coefficient = 0.059, P = 0.003). In conclusion, higher levels of fasting insulin, C-peptide, and circulating leptin level predicted visceral fat accumulation independent from subcutaneous fat accumulation in nondiabetic Japanese-American men and women in both short-term (5 years) and long-ter