Anti-diabetic actions of Berry polyphenols – Review on proposed mechanisms of action

The incidence of type 2 diabetes mellitus (T2DM) has reached near-epidemic proportions in the Western world with other parts of the world following close behind. Glycemic control is paramount in type 1 diabetes mellitus (T1DM) and T2DM. Berries may beneficially influence glycemic control through the action of their polyphenolic components. While clinical studies on the anti-diabetic effects of berry polyphenols are limited, epidemiological data have indicated favorable effects of berry/anthocyanins intake on development and/or management of T2DM. Furthermore, data derived from in vivo animal studies and in vitro cell culture models are promising. Various molecular targets and modulation of cell signaling pathways in pancreatic β-cells, hepatocytes, adipocytes, and skeletal muscle cells are among the proposed mechanisms for berry polyphenols and their metabolites’ action. Berry polyphenols may exert anti-diabetic effects by (i) enhancing insulin production and reducing apoptosis and promoting proliferation of pancreatic β-cells, (ii) regulating glucose metabolism by interfering with absorption or by increasing peripheral tissue glucose uptake through insulin receptor-dependent or independent mechanisms via modification of oxidative stress, inflammation or perceived energy status of cell. This mini review discusses recent findings from our laboratory and other studies on the anti-diabetic effects of berry polyphenolic compounds with special emphasis on the cellular and molecular mechanisms involved in the beneficial effects of berry polyphenol compounds.