The effects of a 12-week lifestyle intervention on incretin response during an oral glucose tolerance test in Latino youth with obesity and impaired glucose tolerance

Gastric inhibitory polypeptide (GIP) and glucagon-like peptide-1 (GLP-1), the two incretin hormones, play an important pathophysiological role in glucose homeostasis with insulinotropic effects on the pancreatic β-cells. While two previous studies in youth have examined the effects of a lifestyle intervention on incretin concentrations, neither study focused on improvements in glycemic status or oral glucose tolerance test (OGTT)-derived biomarkers. Therefore, we aimed to examine changes in the incretin responses during an OGTT before and after a 12-week lifestyle intervention in Latino youth with obesity and impaired glucose tolerance (IGT). A total of 9 Latino youth with obesity and IGT underwent a two-hour OGTT with 30-min blood samples collected for the measurement of glucose, insulin, and incretin hormones before and after the lifestyle intervention (nutrition education and 180 min of moderate-vigorous exercise weekly for a total of 12 weeks). From pre- to post-intervention, a trend towards reduction was observed in the total GIP area under the curve (AUC) during the OGTT (5499.1 ± 715.3 vs. 4085.2 ± 389.5 pg/mL, p = 0.059), with no change in GLP-1. Moreover, BMI%, glucose AUC, and two-hour glucose concentrations were significantly reduced after the intervention. Our data suggest that a lifestyle intervention in Latino youth with obesity and IGT could influence incretin and glucose metabolism. Future studies should examine if the GIP response to a lifestyle intervention is mediated by baseline glycemic status.