Hypertension has long been recognised both as a complication of diabetes and as a major risk factor for the progression of vascular disease. In type 1 diabetes it is mainly seen in association with incipient nephropathy, and the introduction of intensified blood pressure control transformed the prognosis of this condition. Blood pressure control reduces the progresson of retinal as well as renal disease in both forms of diabetes. In type 2 diabetes, hypertension is a common component of the "metabolic" syndrome of dysglycaemia, hypertension, hyperlipidaemia and central obesity, with insulin resistance as a possible aetiological driver. Hypertension is 2-3 times as common in type diabetes as in non-diabetes, and is associated with a two-fold mortality. Given the major importance of blood pressure in the pathogenesis of stroke and heart disease, and the very high morbidity and mortality of cardiovascular disease in diabetes, careful monitoring and rigorous control of blood pressure are essential components of management.