Insulin Sensitivity Is an Important Determinant of Renal Health in Adolescents With Type 2 Diabetes

OBJECTIVE Diabetic nephropathy (DN) remains the most common cause of end-stage renal disease and is a major cause of mortality in type 2 diabetes. Insulin sensitivity is an important determinant of renal health in adults with type 2 diabetes, but limited data exist in adolescents. We hypothesized that measured insulin sensitivity (glucose infusion rate [GIR]) would be associated with early markers of DN reflected by estimated glomerular filtration rate (eGFR) and albumin-creatinine ratio (ACR) in adolescents with type 2 diabetes. RESEARCH DESIGN AND METHODS Type 2 diabetic (n = 46), obese (n = 29), and lean (n = 19) adolescents (15.1 +/- 2.2 years) had GIR measured by hyperinsulinemic-euglycemic clamps. ACR was measured and GFR was estimated by the Bouvet equation (combined creatinine and cystatin C). RESULTS Adolescents with type 2 diabetes had significantly lower GIR, and higher eGFR and ACR than obese or lean adolescents. Moreover, 34% of type 2 diabetic adolescents had albuminuria (ACR >= 30 mg/g), and 24% had hyperfiltration (>= 135 mL/min/1.73m(2)). Stratifying ACR and eGFR into tertiles, adolescents with type 2 diabetes in the highest tertiles of ACR and eGFR had respectively lower GIR than those in the mid and low tertiles, after adjusting for age, sex, Tanner stage, BMI, and HbA(1c) (P = 0.02 and P = 0.04). GIR, but not HbA(1c), LDL, or systolic blood pressure, was also associated with eGFR after adjusting for sex and Tanner stage (beta +/- SE: -2.23 +/- 0.87; P = 0.02). CONCLUSIONS A significant proportion of adolescents with type 2 diabetes showed evidence of early DN, and insulin sensitivity, rather than HbA1c, blood pressure, or lipid control, was the strongest determinant of renal health.