Ganoderan B increased the plasma insulin level in normal and glucose-loaded mice but elicited no effect on insulin binding to isolated adipocytes. Administration of ganoderan B elicited significant increases of the activities of hepatic glucokinase, phosphofructokinase and glucose-6-phosphate dehydrogenase, decreased the hepatic glucose-6-phosphate and glycogen synthetase activities and did not affect the activities of hexokinase and glycogen phosphorylase. Ganoderan B reduced the glycogen content in the liver but had no influence on total cholesterol and triglyceride levels in the plasma and liver.