People with diabetes mellitus are at increased risk of cardiovascular disease (CVD). There is a higher prevalence of recognized risk factors, such as hypertension and abnormal blood lipids, in the diabetic population and this may account for some of the increase in risk. However, the epidemiological evidence suggests that hyperglycemia per se is itself a risk factor for CVD, with no evidence of a lower threshold below which risk does not continue to fall. In the past, the cut-offs for considering an individual to have diabetes or not have been determined according to the risk of microvascular complications. If the relationship between glycemia and macrovascular complications is continuous throughout the range it may be arbitrary what level is used for diagnosis. Trials of lipid-lowering, and blood pressure reduction in diabetes have shown significant benefits for CVD prevention. This applies both to the reduction of elevated levels of blood pressure and cholesterol and, more recently, to lowering of these risk factors within the "normal" range. Randomized evidence for glucose lowering is not as conclusive, but it seems likely that glucose control should be treated in a similar manner.