Diabetes mellitus in the Pima Indians: genetic and evolutionary considerations.

Non-insulin-dependent diabetes mellitus is a common disease in the Pima Indians. It is familial and strongly related to obesity. Neel (1962) suggested that the introduction of a steady food supply to people who have evolved a "thrifty genotype" leads to obesity, insulin resistance, and diabetes. Our findings in the Pimas of differences in insulin sensitivity in different metabolic pathways suggest that the thrifty genotype involves the ability of insulin to maintain fat stores despite resistance to glucose disposal. The recent increase in diabetes incidence following the availability of an abundant food supply suggests that the ability to store energy efficiently during cycles of feast and famine may now lead to obesity, insulin resistance, and diabetes.