Investigating how dietary protein impacts the liver-alpha cell axis and insulin clearance in Black African and Caribbean adults with type 2 diabetes

Black African and Caribbean (BA) populations are disproportionately affected by type 2 diabetes (T2D), with a greater prevalence and earlier age of onset, compared to their White European counterparts. BA populations may also have an alternative pathogenesis of T2D, with defective insulin clearance being a primary abnormality. Insulin clearance is modulated by plasma glucagon, which is stimulated in turn by dietary protein intake – a feedback loop known as the liver-alpha cell axis. We will investigate this relationship in a BA population. In a pilot study of 8 BA men and women with T2D, aged 40-75 years, we will provide 3 doses of dietary protein (0, 0.15 and 0.4 g/kg) on three separate experimental visits, to stimulate plasma glucagon secretion, and assess postprandial hepatic insulin clearance, plasma glucagon, blood glucose and plasma insulin and C-peptide. These findings will determine whether the primary defect in BA populations, impaired insulin clearance, is mediated by plasma glucagon, and whether we can manipulate this through quantity of dietary protein ingestion. This pilot study will have important implications for the further understanding of T2D disease pathophysiology in BA populations, and for the dietary management of T2D in BA populations.