The state of hyperinsulinemia/insulin resistance determines the likelihood that an individual will develop premature atherosclerotic vascular disease. Therefore, various methods to assess in vivo insulin sensitivity have been developed. In adults, it has been shown that the hyperglycemic clamp assesses both insulin sensitivity and insulin secretion in the same individual simultaneously. Our study aimed to determine if in children the insulin sensitivity index derived from a hyperglycemic clamp is a reliable estimate of insulin sensitivity during a hyperinsulinemic-euglycemic clamp.

34 healthy children (age 12.6±0.3 yrs; 18M, 16F; 9 prepubertal, 25 pubertal; 15 Black, 19 White) were studied. Each participated in a 2h hyperglycemic clamp (225mg/dl) & a 3h hyperinsulinemic(40mU/m2/min)-euglycemic clamp in random order. Insulin sensitivity during the euglycemic clamp (IS-EU) was calculated over the last 30 min by dividing glucose disposal rate by steady state insulin concentration. During the hyperglycemic clamp insulin sensitivity index (IS-HY) was calculated over the last 60 min by dividing glucose disposal rate by endogenous insulin levels.

During the hyperglycemic clamp insulin sensitivity was 12.0±1.4 mg/kg/min per uU/ml, first phase insulin was 126.6±18.6 uU/ml, and second phase insulin was 146.1±15.5 uU/ml. During the euglycemic clamp, insulin sensitivity was 10.6±1.0 mg/kg/min per uU/ml. The correlation between IS-HY and IS-EU was r=0.82, p=0.005 in the total group. This correlation was stronger in males (r=0.87, p<0.001) than in females(r=0.55, p=0.01), comparable in prepubertal (r=0.78, p=0.007) and pubertal subjects (r=0.79, p=<0.001) as well as White (r=0.76, p<0.001) and Black children (r=0.74, p=0.001).

In summary, the hyperglycemic clamp technique is a reliable method to assess both insulin secretion and sensitivity in children and adolescents, in a single experiment.