GCK and type 2 diabetes mellitus: Catechin maintains a low level of hemoglobin A (1c) in type 2 diabetics, improves the level of glucokinase, glucose-6 phosphatase, glycogen synthase, and glycogen phosphorylase, decreases the level of cholesterol and triglycerides, and induces the restoration of the structure of the artery wall and cerebral blood flow [40].