Glucose and Free Fatty Acid Metabolism in Obese Adolescents

Abstract

Blood glucose and plasma free fatty acid (FFA) concentrations were measured in fourteen obese and twelve normal adolescents before and after infusions of glucose, epinephrine and insulin, and the institution of a 24 hour fast. Initial mean fasting concentrations of FFA for obese and normal subjects were significantly higher than the mean for normal adults. Initial mean fasting concentrations of FFA and glucose did not differ significantly between obese and control adolescent subjects. A significantly lower blood glucose level was noted in obese subjects 4 hours after glucose infusion. The half-time disappearance as well as the FFA response was normal after glucose infusion. The mean blood glucose concentrations in the obese subjects were lower than those in the normal subjects 5 and 15 minutes after epinephrine infusion. There was a significant delay in FFA response to epinephrine in the obese subjects. FFA response to insulin infusion was diminished in the obese subjects. No significant differences were noted in the glucose response to insulin in either group. Prior to fasting, the initial FFA concentration was abnormally high in the obese subjects. There were no significant differences in FFA or glucose response to fasting between the two groups. It is suggested that the response of plasma FFA, but not blood glucose, to insulin is diminished in obese adolescents. Some evidence is presented for a decreased glycogenolytic response to epinephrine in obese adolescents.