1. Diabetes is a major global public health problem. The prevalence of this disease is predicted to increase sharply in the coming decades, particularly in less-developed regions of the world. 2. Most premature morbidity and mortality associated with diabetes relates to markedly increased risks of major cardiovascular diseases, such as myocardial infarction and stroke (macrovascular events), as well as microvascular complications, such as nephropathy and retinopathy. 3. Hypertension is a prevalent and important risk factor for vascular events in these patients. However, observational data demonstrate a continuous relationship between blood pressure and risk of vascular events, suggesting that even those individuals considered normotensive may benefit from blood pressure lowering. 4. Trials of blood pressure lowering among mostly hypertensive individuals with diabetes have demonstrated benefit of intervention on macrovascular and microvascular outcomes. Recent data may suggest additional effects of angiotensin- converting enzyme inhibitors independent of blood pressure lowering. 5. Issues where data are lacking with respect to blood pressure lowering in diabetes include the effects of blood pressure lowering among non-hypertensive individuals and the effects of blood pressure lowering regimens based on different classes of drug. 6. Data expected to address some of these issues are being collected. These include a prospective meta-analysis of blood pressure-lowering trials with large numbers of patients with diabetes. A new large-scale randomised trial, ADVANCE (Action in Diabetes and Vascular Disease), is also described.