Diabetes among the three affiliated tribes: correlation with degree of Indian inheritance.

The health records of all members of the Three Affiliated Indian Tribes of Fort Berthold, North Dakota were reviewed in order to define the extent of diabetes in this population. Full-inheritance Indians age 35 years and older have a known prevalence rate of diabetes of 22.3 per cent; persons between half- and full-inheritance Indian have a rate of 14.9 per cent; persons less than one-half Indian inheritance have a rate of 4.1 per cent, the same as whites living on this reservation. Below age 35, diabetes is rare among all racial subgroups.