GLP-1, GIP, and Glucagon Excursions During a Mixed Meal Tolerance Test in Young and Lean South Asians Versus Europids

Aims South Asians exhibit an unfavourable metabolic phenotype characterized by visceral obesity, insulin resistance and dyslipidemia. While various hormones play a critical role in regulating postprandial energy metabolism, it remains unclear whether they respond differently to food intake. We aimed to compare the meal-induced excursion of incretin hormones (GLP-1 and GIP) and glucagon between South Asians and Europids.Materials and Methods Forty nine young, lean South Asian (n = 24), and Europid (n = 25) males and females underwent an extended (up to 240 min) mixed meal tolerance test (MMTT). At seven time points circulating incretins (active and total GLP-1 and GIP), glucagon, and parameters related to glucose (i.e., glucose, insulin) and lipid metabolism were measured.Results In response to the MMTT, Europids generally exhibited a single peak in glucose levels at t = 30 min, while South Asians tended to display a biphasic glucose response, with peaks at t = 30 and t = 90 min. Among South Asian males, this was accompanied by an increased insulin response, characterized by elevated levels at the corresponding glucose peaks. South Asian females, however, demonstrated a marked drop in circulating glucagon at t = 90 min, and biphasic excursions of total and active GLP-1 and GIP (t = 30 and t = 120 min). Postprandial lipid excursions did not differ between ethnicities.Conclusions In contrast to a monophasic glucose response to the MMTT of Europids, South Asians tended to exhibit a biphasic glucose response, with sex-specific hormonal patterns, suggesting altered incretin and insulin dynamics despite similar postprandial lipid excursions.Trial Registration ClinicalTrials.gov (NCT05829018; registration date: 25-04-2023)