World-wide morbidity and mortality statistics of the disease and data on the longevity and causes of death of diabetics are reviewed and summarized. Estimates of the global prevalence of diabetes which run as high as thirty million are unreliable. Known diabetics in the United States number about two million or eleven per 1,000 population. The proportion increases with age from about one in 900 for persons under twenty-five years of age to one in twenty for those sixty-five and over. For many countries deaths ascribed to diabetes comprise less than half of all persons dying with the disease. Death rates range from 23.2 per 100,000 population in Belgium down to 0.4 in South Korea. In most countries the death rate from diabetes among females exceeds that among males. Recent mortality trends, however, are more favorable for females generally than for males. Longevity of diabetics has substantially increased, although it remains significantly less than that of nondiabetics. Among patients of the Joslin Clinic first observed in 1940 and later, the survivorship rate after ten years exceeded 90 per cent for patients under thirty years of age, and even for sixty- to seventy-four-year-old patients it was 40 per cent. Today more than ever the chief problem is the prevention and control of vascular complications.