The prevalence of diabetes is two- to threefold higher in American Indians in Montana compared with the non-Indian population. High rates of diabetes have also been described in Canadian aboriginal populations closely related to the tribes in Montana. Diabetes in pregnancy has increased among Indian mothers and high-birth-weight babies are increasingly likely to be born to Indian mothers with diabetes in pregnancy. Over 70% of the incident cases of diabetes in youth less than 20 years of age on the reservations have the clinical characteristics of type 2 diabetes. Cardiovascular disease mortality rates are high among Indians in Montana, and the prevalence of smoking in the Indian populations of Montana and the neighboring tribes in Canada is remarkably high. Indians in Montana are more likely than non-Indians of similar age to believe that diabetes is preventable and to recall advice about diabetes risk.