We are currently measuring insulin binding, glucose transport, glucose metabolism, and lipolysis in adipocytes isolated from human subcutaneous abdominal tissue of Pima Indians. Subjects with normal glucose tolerance and with two nondiabetic parents or one diabetic parent have also been studied. In addition, subjects with glucose intolerance or diabetes have been studied as part of a cross sectional study in the Pima Indians. We have shown that adipocytes from diabetic subjects have altered adipocyte metabolism (i.e. decreased glucose transport and metabolism and increased basal lipolysis without any change in insulin binding). We have also shown that the capacity defects, but not the sensitivity defects, can be improved with improved glycemia via insulin therapy. In the current year we have now determined that sensitivity of glucose transport to insulin (1/ED50) in subjects with abnormal but not impaired glucose tolerance were almost half of that found in subjects with normal glucose tolerance. The subjects were matched for age, sex, obesity, fasting glucose and insulin concentrations and adipose cell size. There were no differences in capacity of transport, metabolism or lipolysis, insulin binding, as well as the sensitivity of antilipolysis to insulin. Thus, the sensitivity of glucose transport to insulin appears to be lower in subjects with abnormal glucose tolerance, due to a post binding defect in the coupling of insulin binding to glucose transport which preceeds the glycemia associated with NIDDM. This may explain why this sensitivity defect was not improved with improved glycemia while the other defective parameters of adipocytes metabolism associated with NIDDM were improved. We also are attempting to determine whether the differences in parental diabetic status influence the parameters of glucose metabolism independent of changes in glucose tolerance. We are comparing in vitro adipocyte data with the in vivo data to determine whether the changes in in vitro adipocyte metabolism parallel those of in vivo glucose metabolism.