PUBERTAL CHANGES IN INSULIN-SECRETION AND PERIPHERAL INSULIN SENSITIVITY

Using a simple and standardized method we estimated both insulin secre tion and insulin sensitivity in peripheral tissues in relation to Tann er pubertal stages. Early insulin response, mean blood glucose (MBG), mean serum insulin (MSI), glucose uptake rate in peripheral tissues an d insulin sensitivity index (SI) in response to the standard oral gluc ose tolerance test were evaluated in 73 normal girls. Study subjects w ere divided into 4 groups: group 1 (Tanner stage I, n = 20); group 2 ( Tanner stage II, n = 14); group 3 (Tanner stages III and IV, n = 15), and group 4 (Tanner stage V, n = 24). Steroid levels and insulin-like growth factors were determined to characterize clinical pubertal devel opment. MBG was similar in all groups but MSI increased at stage II an d retained similar values throughout puberty, with those of group I be ing statistically lower than in the other groups (p < 0.001). When MSI values were adjusted per kilogram of body weight, a significant incre ase was observed in group II (p < 0.05). The MSI adjusted values were: group 1, 1.0 +/- 0.4; group 2, 1.4 +/- 0.4; group 3, 1.0 +/- 0.3, and group 4, 1.0 +/- 0.4 mU/l/kg. SI values were similar in groups 1 and 2 and significantly lower than in groups 3 and 4 (p < 0.001). Our resu lts confirm both that insulin secretion is related to age and that an insulin-resistant state occurs during puberty. Thus, the insulin-resis tant state coincides with Tanner stage II. In conclusion, this mathema tical approach is considered to be a simple and reliable method for an alyzing the possible alterations in insulin secretion and action in ch ildren and adolescents in whom more sophisticated procedures must be l imited in this early period of life for ethical reasons.