A total of 494 persons with normal and borderline types of glucose tolerance (GTT) with relation to diabetes mellitus were examined to analyse dependence of the frequency of the diabetic type of the prednisolone-glucose tolerance test (PGTT) on the presence and combination of the following risk factors: heredity aggravated by diabetes mellitus, excess body mass and the presence of disturbed glucose tolerance of the borderline type in the age aspect. A significant rise of the frequency of the diabetic type PGTT in the presence of the borderline type GTT or obesity and the absence of influence of heredity aggravated by diabetes mellitus was established in persons under and over 40 as compared to the control group. An increase in the number of risk factors (2-3) brought about significant rise of the frequency of the diabetic type PGTT in both age groups. A significant rise of the frequency of the diabetic type PGTT was noted in persons aged 40 and older as compared to the group aged under 40 with obesity combined with the borderline type GTT. For early detection of disturbed glucose tolerance the PGTT is recommended to persons with heredity aggravated by diabetes mellitus, obesity and the borderline type GTT and their combination, particularly in advanced age groups. Therapeutic measures are recommended to persons with the diabetic type PGTT.