Hyperglucagonemia in youth is associated with high plasma free fatty acids, visceral adiposity, and impaired glucose tolerance.

Abstract

To delineate potential mechanisms for fasting hyperglucagonemia in childhood obesity by studying the associations between fasting plasma glucagon concentrations and plasma lipid parameters and fat compartments. Cross-sectional study of children and adolescents with obesity (n = 147) and lean controls (n = 43). Differences in free fatty acids (FFAs), triglycerides, insulin, and fat compartments (quantified by magnetic resonance imaging) across quartiles of fasting plasma glucagon concentration were analyzed. Differences in oral glucose tolerance test (OGTT) glucagon response was tested in high vs low FFAs, triglycerides, and insulin. Human islets of Langerhans were cultured at 5.5 mmol/L glucose and in the absence or presence of a FFA mixture with total FFA concentration of 0.5 mmol/L and glucagon secretion quantified. In children with obesity, the quartile with the highest fasting glucagon had higher insulin (201 ± 174 vs 83 ± 39 pmol/L, P < .01), FFAs (383 ± 52 vs 338 ± 109 μmol/L, P = .02), triglycerides (1.5 ± 0.9 vs 1.0 ± 0.7 mmol/L, P < .01), visceral adipose tissue volume (1.9 ± 0.8 vs 1.2 ± 0.3 dm3 , P < .001), and a higher prevalence of impaired glucose tolerance (IGT; 41% vs 8%, P = .01) than the lowest quartile. During OGTT, children with obesity and high insulin had a worse suppression of glucagon during the first 10 minutes after glucose intake. Glucagon secretion was 2.6-fold higher in islets treated with FFAs than in those not treated with FFAs. Hyperglucagonemia in childhood obesity is associated with hyperinsulinemia, high plasma FFAs, high plasma triglycerides, visceral adiposity, and IGT. The glucagonotropic effect of FFAs on isolated human islets provides a potential mechanism linking high fasting plasma FFAs and glucagon levels.