Diabetes is associated with the development of premature cardiovascular disease. In the three early trials of statin therapy for patients with established coronary heart disease there were many patients with diabetes; subgroup analysis has confirmed the benefits of cholesterol lowering with statin therapy in these patients. In the two early primary prevention trials, however, there were few patients with diabetes and so, initially, there was little evidence supporting the use of statins in diabetic patients without cardiovascular disease. The Heart Protection Study (HPS) and Collaborative AtoRvastatin Diabetes Study (CARDS) have now provided this evidence and firmly established that cholesterol lowering is of benefit in reducing cardiovascular events in patients with type 2 diabetes, regardless of the level of baseline cholesterol, or the presence or absence of cardiovascular disease. A few recent studies have failed to find benefit in diabetic patients but there are explanations for these negative findings. Ideally all patients with diabetes, especially the middle-aged and elderly, should be treated with statins but it remains uncertain at what age therapy should start and how low to reduce the cholesterol for maximum benefit.