The purposes of the project are to determine the effects of abnormal glucose tolerance on outcome of the pregnancy, to determine long term prognosis for the women and their offspring, and to identify diabetes and impaired glucose tolerance during pregnancy in women in the Gila River Indian Community. By means of a glucose tolerance test as well as chart review, the diabetes status of every woman is determined at two-yearly intervals and during the third trimester of each pregnancy. Pima Indian women were evaluated in cross-sectional and longitudinal analyses. Women who had never been pregnant had a higher prevalence of non-insulin- dependent diabetes and were more obese than women who had been pregnant. Among women followed to age 40 years, those who had not been pregnant by the baseline examination were at significantly higher risk for developing non-insulin-dependent diabetes. This difference could be accounted for by a higher degree of obesity, but controlled for age and obesity, nondiabetic women who had never been pregnant had significantly higher fasting plasma glucose concentrations and higher fasting and 2-hour serum insulin concentrations than nondiabetic women who had experienced at least one pregnancy. We hypothesize that Pima Indian women who have a high risk for non-insulin-dependent diabetes develop obesity and hyperinsulinemia at an early age and may develop an associated hyperandrogenemia and decreased fertility. In another analysis, the abilities of 2-hour post- load plasma glucose and glycosylated hemoglobin to predict diabetes were examined in pregnant nondiabetic Pima Indian women. Third trimester 2- hour glucose, obesity, age and parity each predicted future diabetes, but third trimester glycosylated hemoglobin did not. Thus, we hypothesize that relatively acute changes in glucose tolerance during the third trimester in women later destined to develop non-insulin-dependent diabetes are reflected by the 2-hour glucose but not the glycosylated hemoglobin.