Insulin sensitivity, muscle fibre types, and membrane lipids.

One of the key abnormalities of non-insulin-dependent diabetes mellitus (NIDDM) and related diseases of the "Metabolic Syndrome" is impaired insulin action (insulin resistance). Since skeletal muscle plays a major role in insulin-stimulated glucose uptake and whole-body energy expenditure, it is a central player in carbohydrate and lipid metabolism, and hence in the balance between health and disease. This manuscript seeks to describe the evidence both for involvement in insulin resistance of three major muscle variables: membrane lipid composition, storage triacylglycerol and fibre type mixture; and for the interrelationships between these variables. Taken with results provided in other chapters in this volume, the literature described gives insights into the role that certain dietary fats and physical inactivity may play in the development of insulin resistance and hence the disease cluster of the Metabolic Syndrome.