Based upon the National Diabetes Registry the mortality rates were assessed annually between 1961 and 1987 in the total diabetic population of the GDR. The rise of diabetes prevalence from 724/10(5) up to 3988/10(5) during the 27-year observation period was associated with an increase of relative mortality rates from 466% to 600% in insulin-treated diabetics, from 352% up to 528% in non-insulin-treated diabetics. By calculation of standardized mortality ratios (SMR) it could be shown that excess mortality is dependent on age but not at all on sex. Insulin-treated diabetics exhibited their maximum SMR of 650% to 750% at ages 25 to 45 years, while in non-insulin-treated diabetics the maximum SMR amounted to 450% at ages 25 to 35 years. In contrast to trends of the total relative mortality rates that of the overall age structure adjusted SMR of diabetics was characterized by a declining tendency, which may be a reflection of the improvement in diabetes care in our country, and which underscores the dependence of mortal, ty rates on the methods used for evaluation.