Role of the Gut in the Temporal Changes of β-Cell Function After Gastric Bypass in Individuals With and Without Diabetes Remission
Research Design and Methods: Longitudinal, prospective measures of β-cell function after oral glucose and IV graded glucose infusion in individuals with severe obesity and diabetes studied at 0, 3 (n=29), 12 (n=24) and 24 (n=20) months after RYGB. Data were collected between 2015 and 2019 in an academic clinical research center.
Results: The decreases in body weight, fat mass, waist circumference and insulin resistance after surgery (all p<0.001 at 12 and 24 months), did not differ according to diabetes remission status. In contrast, both the magnitude and temporal changes in β-cell glucose sensitivity after oral glucose differed by remission status (p=0.04): greater (6.5 fold, p<0.01) and sustained in full remitters, moderate and not sustained past 12 months in partial remitters (3.3 fold, p<0.001), minimal in non-remitters (2.7 fold, p=ns). The improvement in β-cell function after IV glucose was not apparent until 12 months, significant only in full remitters, and only ~1/3 of that observed after oral glucose.
Pre-intervention β-cell function and its change after surgery predicted remission; weight loss and insulin sensitivity did not.
Conclusion: Our data show the time course of changes in β-cell function after RYGB. The improvement in β-cell function after RYGB, but not changes in weight loss or insulin sensitivity, drives diabetes remission.