Postprandial glycemic response in different ethnic groups in East London and its association with vitamin D status: Study protocol for an acute randomized crossover trial.

BackgroundIn the UK, Black African-Caribbeans (ACs) and South Asians (SAs) have 3-6 times greater risks of developing type-2 diabetes mellitus (T2DM) and significantly higher prevalence of vitamin D (vitD) deficiency than White Caucasians. East London is among the areas with the highest prevalence of T2DM and the highest proportion of ethnic minority groups. This ethnic health inequality is ascribed to socioeconomic standing, dietary habits, culture, and attitudes, while biological diversity has rarely been investigated.AimThe study aims to investigate the difference in the postprandial glycemic response (PGR), an independent risk factor of T2DM, between ethnic groups (White Caucasians, SAs, and ACs) in East London and its association with vitD status.MethodsThis acute randomized crossover trial will recruit healthy adults (n = 106) in East London between November 2023 and March 2025. Two test drinks are consumed by participants (a glucose drink containing 75 g glucose and pure orange juice) on different occasions. PGRs are monitored before and after drinking every 30 min for up to 2 h via finger prick. A fasting blood sample obtained via phlebotomy will be used for plasma 25(OH)D and relevant tests. A knowledge/perception questionnaire about vitD and a 4-day food diary (analyzing vitD dietary intake) will also be collected. Data will be analyzed using a multiple linear regression model adjusted by confounding factors (age, gender, body mass index, and body fat percentage).SummaryThe study results will be disseminated through journals and conferences, and target stakeholders.