Within the last century the prevalence and mortality rates of diabetes and other degenerative diseases have increased considerably. Simultaneously, there have been marked alterations in the types and amounts of food consumed. One of the most conspicuous dietary changes has been the very considerable rise in sugar intake. Some regard this change specifically as the factor most responsible for the increase in diabetes. In this review, the relationship between rises in sugar intake and prevalences of diabetes and the bearing of sugar intake on obesity are discussed. There is not enough evidence that a high intake of sugar specifically promotes the development of diabetes, but this does not imply that sugar intake is unimportant. Because of the high prevalence of obesity in some populations, restriction of sugar intake is as important as other dietary restrictions.