Although non-insulin-dependent diabetes mellitus (NIDDM) was uncommon among Navajo Indians as recently as the 1960's, the number of Navajos with NIDDM currently exceeds that of any other Tribe in the United States. In addition, the prevalence of gestational diabetes mellitus (GDM) among Navajo women is approximately twice that in the general United States population. Because women with GDM (even those whose glucose tolerance returns toward normal after parturition) represent a high risk group for the subsequent development of NIDDM, interventions to decrease risk factors for NIDDM such as obesity and inactivity may result in the delay or prevention of NIDDM. The overall objective of this proposal for a Collaborative Research Planning Grant is to consolidate a team of scientists, Tribal officials, and Indian Health Service (IHS) staff in order to design a clinical trial of risk factor reduction among Navajo Indian women with previous GDM in an attempt to prevent or delay subsequent deterioration of glucose tolerance. There are three specific aims for the planning phase. The first aim is to establish a mechanism for coordinating the proposed clinical trial with the full collaboration of the Navajo Nation, the Indian Health Service, and scientists from several colleges and universities. The second aim is to prepare an integrated computerized database to be used for identification of eligible participants in the trial, and to harvest existing data from registries and medical records in order to refine sample size estimates for the proposed trial. The third aim is to develop a culturally-acceptable risk-factor reduction intervention program based on appropriate nutrition and physical activity. The intervention program will be based on an extant behaviorally-oriented intervention program which was originally developed for use among Mexican-Americans, but the unique social and cultural factors among Navajo women will be taken into consideration in order to make the intervention appropriate for the target population.