Glucose tolerance and reported physical leisure time activity were studied in middle-aged, 47-54 years old, subjects in a health survey. The mean 2-hour blood glucose value after 75 g oral glucose tolerance tests was higher (p less than 0.001) in 682 subjects with a lower degree of leisure time activity than in 125 subjects who were regularly active at least 2-3 hours per week. The mean 2-hour glucose values in the inactive and active groups, respectively, were 4.61 and 4.09 mmol X l-1 after adjustment for the influence of age, body mass index, smoking and physical job activity by analysis of covariance. The difference between adjusted mean 2-hour glucose values was also significant (p less than 0.001) in the subgroups of 280 low leisure time activity males (4.53 mmol X l-1) and 91 active males (3.93 mmol X l-1). Thus, a relation between physical leisure time inactivity and raised post load blood glucose values seems to exist in the general population.