This study was designed to assess the body fat distribution, and also to investigate the effects of body fat on glucose tolerance and on insulin secretion pattern by body mass in offspring of parents with NIDDM. The subjects consisted of twenty parents with NIDDM who had been admitted to the Department of Internal Medicine or had been seen in the outpatient clinic at Kangnam St. Mary's Hospital, Catholic University between February to March, 1995. Twenty offspring were randomly selected from forty six offspring of twenty healthy people without a family history of diabetes mellitus were matched by sex, age and body mass index(BMI). The results are as follows : 1. mean fasting serum glucose and insulin levels and insulin/glucose ratio were significantly greater in offspring than in the control subjects with BMI>or=25kg/m2 in the offspring and in the BMI<25kg/m2(P<0.05). 2. The total glucose area and insulin area were significantly greater in both the offsping and the control subjects with BMI>or=25kg/m2 than in both the offspring and the control subjects with BMI<25kg/m2(P<0.05). 3. Upper body skinfold thickness, Waist hip ratio(WHR), serum levels of total cholesterol and triglyceride(TG), total dietary calorie intake and protein intake in both the offspring and the control subjects with BMI>or=25kg/m2 were greater than those with BMI<25kg/m2(P<0.05). On the other hand, HDL-cholesterol in both the offspring and the control subjects with BMI 25kg/m2 was lower than those with BMI<25kg/m2(P<0.05). 4. The major variables influencing the total glucose area were subscapular skinfolds thickness and WHR and the major variables influencing the total insulin area were suprailiac skinfolds thickness, WHR, TG and free fatty acid. In the light of the results, glucose intolerance and insulin resistance were affected by body mass index, Upper body fat, WHR, and lipids(TG, Free fatty acid), it is implied that these are influencing factors on total glucose area and total insulin area. The identification of these factors might provide a useful tool to identify individuals at high risk of diabetes mellitus. Therefore, various nursing intervention programs to reduce obesity could be given to both the offspring of parents with NIDDM and to the obese healthy controls before diabetes mellitus develops.