Diabetes mellitus is one of the leading causes of death and disability in the United Sates. Certain Native American groups have been harder hit than the mainstream population, both in prevalence of the disease and in rates of related complications. The highest known prevalence in the world is found among a Southwestern U.S. Tribe, and other Native American Tribes have demonstrated similar prevalence rates. It has been shown that certain psychological factors such as depression and hostility impact both the occurrence and outcome of certain diseases, including diabetes. This study examined whether those individuals who have not met the criteria for diabetes mellitus were more prone to develop diabetes mellitus if they reported signs of depression, cynical hostility, or anger that is either expressed or not expressed. It also examined the impact of depression, cynical hostility, and anger on glucose control among individuals who were diagnosed with diabetes mellitus. Finally, an aim was to determine if "psychological distress, " rather than specific psychosocial variables, was related to poorer diabetic outcomes among a specific Native American population. Participants for this study were part of the Strong Heart Study and were examined at two different points in time (1992-1994 and 1997-1999). The current study found that psychosocial variables did not predict the incidence of diabetes mellitus. Depression was found to impact glucose control among individuals without diabetes or impaired glucose tolerance, but psychosocial variables did not appear to have any measurable influence on glucose control among those individuals with diabetes mellitus or impaired glucose tolerance. Overall, it appears that psychosocial variables do not play as large of role in both incidence and outcome among certain Native American tribes as has been shown among the mainstream population.