Original Abstract

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).