Studies of macrovascular disease in non-insulin-dependent diabetes (NIDDM) have shown a significant increase in peripheral vascular, coronary, and carotid artery disease in diabetics compared to non-diabetics. This prevalence appears to be related to insulin levels and to the degree of hyperinsulinemia as measured in the blood of these patients. Indeed, a cluster of markers, including hyperinsulinemia, insulin resistance, hypertension, dyslipoproteinemia, and a high waist-hip ratio, has been associated with NIDDM and increased risk for macrovascular disease. Variously described as Metabolic Syndrome or Syndrome X, this syndrome may be operative for many years before NIDDM is diagnosed. Given the complexity of Metabolic Syndrome, a single-factor intervention for preventing macrovascular disease in NIDDM is unlikely. However, it seems advisable to screen, on a regular basis, all patients presenting a pre-NIDDM state, as well as those with overt NIDDM, for pertinent cardiovascular risk parameters and for emerging macrovascular disease. It is suggested that any attempt to prevent macrovascular disease in subjects with glucose intolerance should aim at decreasing insulin resistance and hyperinsulinemia.