Altered Plasma Levels of Glucagon, GLP-1 and Glicentin During OGTT in Adolescents With Obesity and Type 2 Diabetes

Context: Proglucagon-derived hormones are important for glucose metabolism, but little is known about them in pediatric obesity and type 2 diabetes mellitus (T2DM). Objective: Fasting and postprandial levels of proglucagon-derived peptides glucagon, GLP-1, and glicentin in adolescents with obesity across the glucose tolerance spectrum were investigated. Design: This was a cross-sectional study with plasma hormone levels quantified at fasting and during an oral glucose tolerance test (OGTT). Setting: This study took place in a pediatric obesity clinic at Uppsala University Hospital, Sweden. Patients and Participants: Adolescents with obesity, age 10–18 years, with normal glucose tolerance (NGT, n = 23), impaired glucose tolerance (IGT, n = 19), or T2DM (n = 4) and age-matched lean adolescents (n = 19) were included. Main Outcome Measures: Outcome measures were fasting and OGTT plasma levels of insulin, glucagon, active GLP-1, and glicentin. Results: Adolescents with obesity and IGT had lower fasting GLP-1 and glicentin levels than those with NGT (0.25 vs 0.53 pM, P < .05; 18.2 vs 23.6 pM, P < .01) and adolescents with obesity and T2DM had higher fasting glucagon levels (18.1 vs 10.1 pM, P < .01) than those with NGT. During OGTT, glicentin/glucagon ratios were lower in adolescents with obesity and NGT than in lean adolescents (P < .01) and even lower in IGT (P < .05) and T2DM (P < .001). Conclusions: Obese adolescents with IGT have lowered fasting GLP-1 and glicentin levels. In T2DM, fasting glucagon levels are elevated, whereas GLP-1 and glicentin levels are maintained low. During OGTT, adolescents with obesity have more products of pancreatically than intestinally cleaved proglucagon (ie, more glucagon and less GLP-1) in the plasma. This shift becomes more pronounced when glucose tolerance deteriorates.