Prevention of coronary heart disease in type 2 diabetes

Patients with diabetes without a prior myocardial infarction are at a similar risk of coronary heart disease (CHD) events as non-diabetic subjects with a prior myocardial infarction. Furthermore, prognosis after the first myocardial infarction is worse in diabetic compared to non-diabetic patients. Therefore, management of cardiovascular risk factors in subjects with diabetes should be as vigorous as in patients with known CHD who have had a myocardial infarction. Randomised controlled trials have shown that efficacy of cholesterol lowering and antihypertensive therapy in type 2 diabetes is at least as effective as in non-diabetic subjects in preventing macrovascular disease. Antiplatelet therapy with aspirin reduces the risk of CHD events in high-risk patients and the benefit is similar in subjects with and without diabetes. Improved glycaemic control has a modest beneficial effect on CHD risk. There is residual excess risk of CHD in type 2 diabetes, which is not explained by traditional cardiovascular risk factors. Insulin resistance may partly mediate this. Prediabetic subjects who are insulin resistant have more adverse levels of triglycerides, high density lipoprotein (HDL)-cholesterol and blood pressure than those who are insulin sensitive. Moreover, factors associated with insulin resistance are significant predictors of CHD events in subjects with diabetes, in addition to conventional risk factors. The thiazolidinedione, pioglitazone, improves glycaemia and insulin sensitivity in hyperglycaemic patients. It also improves insulin and triglyceride levels and lowers blood pressure. Thiazolidinediones have been found to have vasculo-protective effects in both acute and chronic vascular injury in animal models. For prevention of CHD in type 2 diabetes a multi-factorial approach should be considered, including improved glycaemic control, aggressive management of dyslipidaemia and hypertension, anti-platelet therapy, reduction of insulin resistance and use of agents that improve insulin sensitivity.