Metabolic actions of insulin in men and women

Abstract

Insulin is an important regulator of glucose, lipid, and protein metabolism. It suppresses hepatic glucose and triglyceride production, inhibits adipose tissue lipolysis and whole-body and muscle proteolysis, and stimulates glucose uptake in muscle. In this review we discuss what is currently known about the control of substrate metabolism by insulin in men and women. The data available so far indicate that women are more sensitive to insulin with regards to glucose metabolism (both in the liver and in muscle), whereas there are no differences between men and women in insulin action on lipolysis. Potential differences exist in the regulation of plasma triglyceride concentration and protein metabolism by insulin and in changes in insulin action in response to stimuli (e.g., weight loss and exercise) that are known to alter insulin sensitivity. However, these areas have not been studied comprehensively enough to draw firm conclusions.

Figure 1

Summary of the major metabolic actions of insulin. Insulin suppresses hepatic glucose production, stimulates glucose uptake in muscle, suppresses adipose tissue lipolysis and fatty acid release into the blood stream; suppresses hepatic apolipoprotein B-100 and triglyceride secretion, stimulates lipoprotein lipase activity in adipose tissue, and inhibits protein breakdown. Adequate insulin action on adipose tissue lipolysis prevents fatty acid-induced insulin resistance in β-cells, muscle and the liver.