Elevated insulin concentrations are frequently found in both men and women with coronary heart disease (CHD), and are likely to be due to insulin resistance. Hyperinsulinaemia may increase CHD risk by directly promoting atherogenesis, and insulin propeptides may also be important in this respect. However, increased insulin concentrations may adversely affect several other CHD risk factors, and it has been postulated that insulin resistance is a pivotal metabolic disturbance in a constellation of CHD risk factors. There is an association between hyperinsulinaemia and hypertension, although it is not known if this association is direct. Increased insulin concentrations are also associated with high triglycerides, low HDL or HDL2 concentrations, and increased small dense LDL. Obesity is also associated with insulin resistance, and it is the central or android body fat distribution which correlates with these metabolic disturbances. All these associated factors constitute a distinct syndrome--the insulin resistance syndrome--which is a frequent finding in patients with CHD, including microvascular angina. It is possible that the adverse associations of insulin resistance and dyslipidaemia are mediated through increased nonesterified fatty acid flux. Increased insulin levels are also associated with increases in the anti-fibrinolytic factor, plasminogen activator inhibitor-I (PAI-I). Whilst increased insulin levels are typically associated with insulin resistance, reduced hepatic insulin uptake may also be important. We now have techniques which can quantitate insulin secretion, hepatic uptake and release, elimination, and resistance. The menopause has appreciable effect on insulin and glucose metabolism. Estrogen and progesterone augment pancreatic insulin secretion, but the former reduces insulin resistance whilst the latter increases it.(ABSTRACT TRUNCATED AT 250 WORDS)