Pima Indians

The Pima Indians of the Gila River Indian Community in Arizona have very high rates of obesity and Type 2 diabetes. Both genetic and environmental risk factors contribute to the high rates of diabetes in this community. One-half of adult Pima Indians over the age of 35 years have Type 2 diabetes and 95 percent of those with Type 2 diabetes are overweight. Collaboration with the community in understanding the extent and cause of Type 2 diabetes and obesity in this population has been ongoing since 1965. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) has established a branch in the southwest (the Phoenix Epidemiology and Clinical Research Branch) specifically to work with the community to investigate the causes and complications of obesity and Type 2 diabetes.

From this collaboration, risk factors for development of weight gain and development of Type 2 diabetes have become clearer. Higher body weight itself is an important risk factor for Type 2 diabetes. Other important risk factors for diabetes include the decreased ability of insulin to metabolize blood sugar (insulin resistance), family history of diabetes, exposure to diabetes in utero, and mild elevation of blood sugars.

Risk factors for weight gain in this population include lower insulin resistance (or higher insulin sensitivity), lower metabolic rate measured at rest or over 24 hours, lower activity of the sympathetic nervous system (thought to play an important role in the rate of body metabolism), and lower concentrations of thyroid hormone.

Complications from Type 2 diabetes, including eye, kidney, and vascular disease, cause a substantial amount of morbidity for this population. In fact, mortality from cardiovascular and kidney disease are much higher in Pima Indians with diabetes compared to those without diabetes. Therefore, treatment and prevention have also been main targets of research for the NIDDK. Members of the Gila River Indian Community participated as volunteers in a large clinical trial (the Diabetes Prevention Program) that has shown that lifestyle modification (modest weight loss of about 15 pounds and habitual physical activity of 150 minutes per week) can prevent or delay the development of Type 2 diabetes. Members of this community are also participating in a clinical trial to test the effect of weight loss on development of cardiovascular disease in individuals with Type 2 diabetes and a clinical trial to investigate the impact of medication to delay worsening of diabetes-related kidney disease.

Collaboration with the Pima Indians of the Gila River Indian Community has improved our understanding of the causes of Type 2 diabetes and obesity, and has led to progress in diabetes prevention. These advances have both directly, via participation in these intervention studies and subsequent programs modeled on such studies, and indirectly, via advances in treatments based on findings from these studies, improved care for Gila River Indian Community members at risk for and with Type 2 diabetes.