The relationship between body fat and different aspects of glucose tolerance was examined within the Zutphen Study. In 1970 an oral glucose tolerance test (OGTT) was carried out in 404 non-diabetic men aged 50-70. None of the subjects could be classified as having impaired glucose tolerance. Body mass index (BMI), subscapular and triceps skinfold were positively related with fasting and 60 min serum glucose. Weak positive associations were found between 30 min glucose, BMI, and subscapular skinfold. For 120 min glucose, only the relationship with subscapular skinfold was significant. After adjustment for age and the other body fat indicators, the positive associations between body fat and fasting, 60 min and 120 min glucose were confirmed for subscapular skinfold only. Correlations between these glucose measurements and measurements of subscapular skinfold in the years between 1960 and 1970 were also significant and increased with time. Independent from subscapular skinfold in 1970 and age, changes in skinfold during the period 1960-70 were in general not significantly associated with glucose levels, except for 30 min glucose. The findings could to a large extent be explained by current knowledge of glucose metabolism.