Of the threats to health and life that beset the person with diabetes, cardiovascular disease (CVD), particularly coronary heart disease (CHD) but also cerebrovascular and peripheral vascular disease, represent the heaviest burden. The relative risk for CVD is very high for Type 1 diabetes, but the absolute risk, in terms of numbers, is much higher for Type 2. In all societies, diabetes increases cardiovascular risk twofold or more, compared with the local non-diabetic population. Some of the evidence for this diabetes-related increase in cardiovascular risk is reviewed and its relationship to recognised cardiovascular risk factors considered. The explanation of the enhanced susceptibility to atherosclerotic disease in diabetes remains a matter of contention. How much can be explained by greater prevalence in diabetes of such risk factors as hypertension and dyslipidaemia? To what extent is the impact of a given level of risk factor magnified by a co-existing diabetic state? Is the increased cardiovascular morbidity and mortality secondary to risk factors specifically related to the diabetic state itself? Does the explanation lie in altered coagulability due to changes in platelet activation and aggregability, fibrinogen levels, Factor VII, von Willebrand factor or PAI-1, in the concentration or composition of plasma lipoproteins, in defective endothelial cell function or other metabolic abnormalities of the arterial wall? To what extent is cardiovascular risk related to the degree of hyperglycaemia, protein glycation, relative hyperinsulinaemia and insulin resistance? Data from recent epidemiological, intervention and laboratory investigations bearing on causation, management and prevention of CVD in diabetes are reviewed. Evidence for the impact of correction of glycaemia, dyslipidaemia and raised arterial pressure is considered and reasons are adduced for a broad and proactive therapeutic approach with early identification and vigorous correction of key risk factors. Copyright (C) 1999 John Wiley & Sons, Ltd.