_Functional overstrain the chief cause of diabetes._--Functional overstrain is a recognized cause of disease, especially of the heart, but also of other organs. The heart may be irreparably injured by excessive exertion. Functional overstrain of the pancreatic islands resulting from long continued overeating is a cause of much diabetes. Persons who persistently overeat are usually markedly overweight. Some thin people are also equally prone to overeat, and yet, for some thus far unknown reason, remain thin. _Obesity a mark of overeating and functional overstrain of the pancreas._--The rule, however, is that overeating leads to obesity, and it is a well known fact that many diabetic patients are, or have been, overweight. Dr. Joslin, for instance, found among 1,000 diabetic patients, 75 per cent who either were, or had been, over normal weight. Dr. Joslin says that it takes ten diabetic patients to make a ton of diabetes. Overeating with attendant long continued functional overstrain of Langerhans islands is probably the most common of all causes of diabetes. _Sugar eating._--It is of considerable significance that the increasing incidence of diabetes in America is coincident with the enormous increase in the sugar consumption. In the decade 1880 to 1890, the annual sugar consumption was 44 pounds per capita. In 1921, it had risen to 84 pounds, and in 1922 to 103 pounds. The death rate for diabetes in 1890 was 5.5 for each 100,000; in 1921, it was 16.8 for each 100,000. It is easier to overeat of sugar than of almost any other food known, and it is probable that sugar imposes a greater functional strain on the pancreas than do the starches or fats. Starches swell up and fill the stomach readily, thus checking the appetite; furthermore they are slowly absorbed into the blood. Sugar goes into solution, passes the stomach quickly, is absorbed almost instantly and at once demands attention from the pancreas. The common desserts are sweets. When we are glutted with meat and potatoes, we still have room for sweets and we can always find room for candies. The rage for soft drinks since the abolition of alcoholic beverages is certain to increase the crop of new cases of diabetes. I have seen several patients who have been suddenly precipitated into an extreme stage of diabetes and coma by a soft drink spree.