Oral glucose tolerance tests (1.75 gm./kg. ideal body weight) were performed on sixty-six obese children and adolescents, four to sixteen years of age. Ten subjects of normal height and weight of the same age range and without a family history of diabetes served as controls. Plasma glucose, immunoreactive insulin, and free fatty acid levels were determined.

Twenty-seven (45 per cent) of the subjects had normal tolerance, fifteen (23 per cent) had distinctly abnormal tolerance. Hyperinsulinemia was observed in nearly all the obese subjects, but it was significantly greater in those with abnormal tolerance than in those with normal tolerance. Free fatty acids fell rapidly after the ingestion of glucose in the majority of subjects. In some there was a delay in return to fasting levels.

Thirty-four of the obese subjects had close diabetic relatives (diabetic family history [DHF+]) and thirty-two did not (DFH −). The incidence of moderately abnormal tolerance in the two groups, was the same but markedly abnormal tolerance was found only in the DFH + group. DFH + children had significantly greater elevations in insulin levels than DFH − children at both levels of tolerance. The DFH + subjects with severe hyperglycemia had somewhat increased levels of insulin occurring only after the first hour of the test.

The hyperinsulinemia observed in the obese children in this study cannot be completely explained by compensatory overproduction due to peripheral resistance to insulin, and an alternate hypothesis is suggested.

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