Research implications: More studies are needed with careful assessments of family history of hypertension, coronary disease, diabetes and lipid abnormalities. Data should be collected about health status of relatives when individuals are screened and perhaps even more importantly, data should be collected from families rather than individuals to understand the relationships discussed above. Research regarding NIDDM should routinely collect data on lipid abnormalities including HDL, VLDL, and LDL (total cholesterol, triglycerides, and calculated LDL and VLDL). In some persons with very high triglyceride levels, ultracentrifugation is indicated for accurate measurements of VLDL and LDL. More studies of fasting and challenge insulin levels and insulin resistance using 'clamp' techniques are needed and perhaps especially in families. In any study involving insulin and lipid abnormalities, it seems appropriate to assess not only amount of body fat but also fat distribution. Special tests such as gene markers and biochemical factors that help understand metabolic effects are needed. Perhaps a better understanding of the exact role of lipoprotein lipase would help understand some of the genetic aspects of NIDDM. Environmental factors should not be ignored. It is clear that modification of dietary fat and carbohydrate intake can affect insulin levels and insulin resistance. Physical activity and medications are other important variables that should be routinely collected. Clinical implications: Persons with NIDDM deserve more attention regarding coronary risk factors (lipids, hypertension, and family history of coronary disease, hypertension and lipid abnormalities). These data would suggest at least a subset of persons with NIDDM have a markedly increased risk of coronary disease that probably derives from some of these factors. It would appear that relatives of persons with NIDDM deserve concern at an earlier stage when glucose metabolism is still compensated but abnormalities in lipids, insulin or blood pressure may be already adding to the risk of future coronary disease. And finally, while behavioral change is difficult to obtain, there are those who are capable of making lifestyle changes that can have significant implications on future coronary risk. Exercise, prudent diet, and weight reduction remain sound advice for persons who have the risks described in this summary review. Individuals who have a strong positive family history of coronary disease and hypertension together with a family history of NIDDM deserve special screening and risk modification because existing data indicate that risk of coronary disease is substantial for them.