High prevalence of diabetes in young Pima Indians: evidence of phenotypic variation in a genetically isolated population.

Medical records of the Pima Indian population aged 0--24 yr were reviewed for a diagnosis of diabetes before initiation of glucose tolerance testing. None of 1556 subjects below age 15, but 6 of 657 aged 15--24, had a previous diagnosis. Of the six known diabetics, five had been treated with insulin and four had had ketoacidosis. Subsequently, plasma glucose levels were determined after a 75-g oral carbohydrate load in 1712 subjects aged 5--24 yr, which is about 78% of the eligible population. Previously diagnosed diabetes and asymptomatic hyperglycemia were more frequent in subjects 15--24 yr old than were reported in other populations. Glucose intolerance in young Pimas was associated with obesity. In Pima offspring, the presence of diabetes in both parents was related to glucose tolerance in those above but not below the age of 15 yr. Both asymptomatic hyperglycemia and insulin-requiring diabetes occurred frequently in young Pimas, suggesting that these syndromes represent the clinical spectrum of a single disease in the Pima Indian.