In a sixteen year follow-up study in Framingham, it was found that diabetics in general show an increased morbidity and mortality from all cardiovascular causes. Insulin-treated diabetic women showed the greatest relative mortality from coronary heart disease. Diabetics were found to have higher lipid values, more hypertension and more obesity, even prior to diagnosis. When all the associated risk factors, individually or together, were taken into consideration their presence could not entirely explain the increase in cardiovascular morbidity and mortality experienced by the diabetic. An as yet unknown factor appears to be present in diabetics that could be responsible for much of the higher incidence of cardiovascular complications in diabetics.