921-P: Do Glucose and Lipid Metabolism Differ by Adiposity in Adolescents with Type 1 Diabetes (T1D)? Preliminary Results of a 2-Step Clamp Study

Puberty is a known stage of insulin resistance in lean adolescents with or without T1D. Moreover, 25% of adolescents with T1D in clinical practice are overweight, which may further contribute to insulin resistance. The present study examines whether higher body fat aggravates insulin resistance in the liver, muscle, and adipose tissue in pubertal adolescents with T1D by performing a 2-step, 8 and 80 mU/m2/min hyperinsulinemic euglycemic clamp. Body Composition was measured by DEXA, abdominal fat by MRI and hepatic fat by MRI-proton density fat fraction (PDFF). Endogenous glucose production and glycerol turnover were traced with [6,6-2H2] glucose and [2H5]-glycerol (Figure). Participants (mean age 14.4±1.2 years, A1c 7.6±0.5%) with lower (22.9) and higher (36.7) mean % body fat had mean weights of 61.6 and 68.1 kg, BMI% 68.3 and 84.8, and PDFF 1.4 and 1.7%, respectively. Endogenous glucose production was partially suppressed across the body fat spectrum during the low dose insulin infusion. In contrast, those with higher body fat tended to have diminished suppression of glucose production during the high dose insulin infusion. Rates of lipolysis appear to be unaffected. Hence our preliminary findings suggest that on the spectrum of increasing body fat in pubertal adolescents with T1D, we start to see metabolic inflexibility in youth with a moderate degree of adiposity. Disclosure M. A. Van name: None. S. Siebel: None. E. M. Tichy: None. S. Caprio: None. W. V. Tamborlane: Consultant; Self; Medtronic, Sanofi, Other Relationship; Self; Tolerion, Inc. N. Santoro: None. Funding National Institute of Diabetes and Digestive and Kidney Diseases (1K23DK115894-01A1)