In the German National Health Interview and Examination Survey 7,124 subjects of a representative sample of the 18 to 79 year old population having their residence in Germany were interviewed and medically examined. Using a self-administered questionnaire as well as a subsequent personal interview by a physician, the participants were questioned regarding past and present diseases. Based on the data of the physicians' interviews, the prevalence rate for diabetes was 4.7% for men and 5.6% for women in the examined age-group. There is a strong increase of the prevalence with age. According to the present data nearly every fifth women in the age range from 70 to 79 years is suffering from diabetes mellitus. The disease is much more frequent in the new federal states (former GDR) than in the old ones (former West Germany). About one fourth of the diabetics uses insulin, far more than 40% are on oral antidiabetics. According to the interrogation of the physicians, about half of the diabetics not using any drugs are not even on a diet (ca. 15%). The portion of undetected diabetics in the examined population is estimated to be about 1% considering the values of blood and urine parameters (glucose in serum and urine, fructosamine, HbA1c).