Effect of insulin therapy on macrovascular risk factors in type 2 diabetes

Many patients with type 2 diabetes require insulin therapy for improved gly cemic control after beta-cell failure. However, many physicians are relucta nt to institute insulin therapy in type 2 diabetes for fear of accelerating atherosclerosis. The epidemiological evidence is reasonably sound that hyp erinsulinism correlates with increased cardiovascular disease in nondiabeti c people and those with early type 2 diabetes. II is much less clear, howev er, that insulin concentration plays a negative role when less well control led diabetes is considered. The data are more consistent, in fact, with the glucose hypothesis, i.e., that hyperglycemia is a risk factor, although th e magnitude of the glucose effect is not well defined. Certainly the dysmet abolism associated with poor glycemic control could increase the risk of ma crovascular events through well-known mechanisms. There is direct evidence that insulin therapy can reduce the risk of macrovascular events by improvi ng glycemic control and diabetes-associated dyslipidemias, although the ben eficial effects may be significantly compromised by excessive weight gain. Insulin therapy does not appear to induce hypertension independent of chang es in body weight. It is concluded that optimal glycemic control confers a known benefit and can only be achieved with insulin therapy in some people with type 2 diabetes. In these circumstances, the use of insulin has a net benefit on cardiovascular risk, mediated primarily through improvement in d yslipidemia and glycemia itself.