Cardiovascular risk factors and the prediabetic syndrome

Cardiovascular disease is increased 2- to 4-fold in non-insulin-dependent diabetes mellitus (NIDDM); yet in most studies, there is a relatively weak relationship between the frequency of coronary heart disease (CHD) and the duration of diabetes and severity of hyperglycaemia. A number of authors have suggested that the prediabetic stage may contribute to the risk of CHD in NIDDM. Hyperinsulinaemia and insulin resistance have been strongly associated with the development of NIDDM. Data are less conclusive about the relationship of hyperinsulinaemia to the development of CHD in nondiabetic subjects. Relatively little data are available on hyperinsulinaemia and/or insulin resistance to CHD in NIDDM subjects. Tight control of glycaemia with exogenous insulin improves cardiovascular risk factors in NIDDM subjects and therefore is unlikely to increase the risk of CHD. Although the relation of insulin to CHD in the general population is somewhat controversial, insulin is clearly related to multiple cardiovascular risk factors (especially elevated triglyceride, decreased high-density lipoprotein, small dense low-density lipoprotein, impaired glucose tolerance and increased plasminogen activator inhibitor 1 (PAI-1)). However, the relation of insulin resistance to hypertension remains controversial.