1559-P: Differential Effects of Type 1 (T1D) and Type 2 Diabetes (T2D) on the Growth Hormone (GH)-Insulin-Like Growth Factor (IGF) Axis in Youth

Abstract

T1D and T2D are characterized by hyperglycemia and insulin resistance (IR), but in T1D the IR occurs even in the absence of metabolic syndrome features. The loss of β-cell insulin secretion in T1D results in lower portal and thus hepatic insulin concentrations in T1D than in T2D or nondiabetic (non-DM) individuals, affecting the GH-IGF axis, as exogenous insulin is subcutaneously delivered in T1D. In this study, we examined how the GH-IGF axis differs by diabetes type, and how it relates to IR. This study included youth (mean age 15±2 years, 37% female) with T1D (n=16), T2D (n=27) and non-DM controls (n=38). A morning fasting blood sample was obtained to measure GH, IGF-1, and IGF binding proteins (IGF BP-1, 2 and 3). Hyperinsulinemic euglycemic clamps were performed to measure glucose infusion rate (GIR), an estimate of skeletal muscle IR, and serum free fatty acid (FFA) suppression. GH, IGF BP-1 and IGF BP-2 were higher in T1D compared to non-DM youth (Figure). Higher IGF BP-3 was associated with lower GIR (more muscle IR) in all youth, but lower IGF BP-1 and 2 were associated with lower GIR in non-DM youth only. Higher GH, IGF BP-1 and IGF BP-3 were associated with less FFA suppression (more adipose IR) in T1D youth only. The GH-IGF-1 axis is altered and is differentially correlated to IR in T1D versus T2D. These data provide clues regarding the unique phenotype of IR in T1D. Disclosure J.K. Snell-Bergeon: None. J.E.B. Reusch: Board Member; Self; American Diabetes Association. Other Relationship; Self; Merck & Co., Inc. A.D. Baumgartner: None. M. Cree-Green: None. K.J. Nadeau: None. Funding American Diabetes Association (7-13-CD-10 to J.K.S-B.)