_Diabetes may occur without provocation._--Not infrequently, among younger persons and children, diabetes appears out of a clear sky with apparently no provoking cause. No inflammation has occurred in the pancreas of these patients, so far as any good evidence shows; they are young and therefore not afflicted with arterial disease, and they have never been overweight and have not overeaten. How can we explain the diabetes of these children and young persons, and how can we explain why some fat persons and not all escape diabetes, and why some patients with very little disease of their pancreas have diabetes and others with very extensive destruction of the pancreas do not have it? _Heredity of the tendency to diabetes._--The answer, probably, lies in the more or less shadowy realm of heredity. Some of us are born with weak eyes and others with weak islands, and the degree of original island weakness determines the susceptibility of the islands both to functional overstrain from overeating and to injury from infectious diseases or from poor circulation of the blood. If the diabetic tendency of an individual is marked, diabetes may develop, in very early life. The pancreas here is too weak to withstand the normal functional strain of growth. When this is the case, the disease is of extreme severity. If the diabetic tendency is slight, it may not show itself except as the result of long continued overeating. If the pancreatic islands are functionally strong, they withstand infections and injury from disease or poor blood supply; if weak, they fail and diabetes results. Diabetes rather infrequently occurs in several members of the same family, but the fact that this happens rather infrequently does not mean that the tendency fails to pass by heredity. Many persons who are considered normal may have this tendency without showing any evidence of it throughout life. THE TREATMENT OF DIABETES