INS and Hyperglycemia: The flavanol epigallocatechin gallate (EGCG), a main component of green tea extract, preserves the insulin secretory machinery; EGCG (10 μm for 48 h) stimulates the activation of the IRS-2 signalling in rat insulinoma pancreatic β-cells (RIN-m5F), also under chronic hyperglycaemia(92).