Inside out the Ragbag of Glucose Intolerance in Obese Adolescents

Background/Aims: The prevalence of impaired glucose tolerance (IGT) is rising among obese adolescents in parallel with epidemic obesity. In some cases, IGT reverts to normal glucose tolerance (NGT) by the end of puberty. The aims of the present study were to investigate metabolic factors determining changes over time of glucose at 120 min (Glu120) following an oral glucose tolerance test (OGTT), and to verify whether preserved ?-cell glucose sensitivity (?CGS) protects against persistent IGT. Methods: We performed a cohort study of 153 severely obese children and adolescents evaluated with a 5-point OGTT at baseline and at follow-up with measurements of glucose, insulin, and C-peptide to estimate several empirical parameters of insulin sensitivity (includ ing oral glucose insulin sensitivity [OGIS] and OGTT-derived glucose effectiveness) and secretion. Results: At follow-up (range 0.9-4.8 year), 113 (73.9%) patients remained with NGT, 9 (5.9%) had IGT, and 28 (18.3%) had reverted to NGT; 3 NGT patients had developed IGT. In multivariable models, change in loge(?CGS) was inversely associated with time-related change in loge(Glu120), with (model 2) and without (model 1) correction for the change in loge(OGIS). Model 2 was more strongly associated with change in loge(Glu120). Conclusions: Changes in ?CGS and insulin sensitivity were inversely associated with changes in Glu120 at follow-up, contributing a likely explanation for the reversal of IGT to NGT.