Intravenous glucose tolerance test in childhood obesity: metabolite levels and their relation to glucose utilization rate (KG).

Intravenous glucose tolerance tests were performed in 33 obese and 12 nonobese children. In addition to the glucose disappearance rate the changes in response to the glucose load in plasma insulin, FFA, glycerol, cholesterol, triglyceride, lactate and pyruvate were examined. The relationship between biochemical parameters and the glucose disappearance rate was also studied. 1. Reduced glucose tolerance, basal and glucose-induced hyperinsulinaemia were frequent in the obese children. 2. Normal or reduced glucose tolerance in spite of the apparent hyperinsulinaemia and the negative correlation between fasting insulin level and KG in the nonhypertriglyceridaemic obese group was the marker of insulin resistance in overweight children. 3. The reduced elevation of FFA in the 2nd hour of the intravenous glucose tolerance test might be the sign of an impaired lipolysis in obesity. 4. The significant negative correlation found between KG, fasting FFA and triglyceride levels in certain obese subgroups suggested the importance of FFA and triglyceride in the regulation of peripheral glucose utilization.