Longitudinal Changes in Insulin Sensitivity, Insulin Secretion, and β-Cell Function During Puberty

ObjectiveTo determine longitudinal changes in insulin sensitivity (SI), insulin secretion, and β-cell function during puberty in white and black youth.Study designThe tolbutamide-modified frequently sampled intravenous glucose tolerance test and minimal modeling were used to measure SI, the acute insulin response to glucose (AIRg), and β-cell function (disposition index, DI) in white (n = 46) and black (n = 46) children (mean [±SD] age at baseline = 10.2 ± 1.7 years). Growth curve models (including 272 observations) with SI, AIRg, and DI regressed on Tanner stage were run after adjusting for covariates.ResultsAfter adjusting for covariates, growth curve models revealed that SI decreased and subsequently recovered by the end of puberty in whites and blacks (both p < .05), AIRg decreased linearly across Tanner stages in both races (both p < .001), and DI decreased across puberty in blacks (p = .001) but not in whites (p = .2).ConclusionsWhite and black youth exhibited transient insulin resistance and diminished AIRg during puberty. The progressive decline in DI among blacks versus whites may reflect a unique effect of puberty on β-cell compensation in blacks. Future studies are needed to identify whether this difference contributes to the increased risk of type II diabetes in young blacks.