In the therapy of diabetes mellitus the avoidance of the late cardiovascular complications is at present the largest problem. By the American UGDP-study the attention was paid to an increased death rate of cardiovascular diseases induced possibly by sulfonyl ureas. Since it is ascertained that the disturbance of the fat metabolism which at the same time is frequently present also in diabetes mellitus significantly disturbs the risk for cardiovascular diseases the problem was pursued, to what extent the parameters of the fat metabolism are unfavourably influenced by a therapy with sulfonyl ureas. The result of the investigations was that by an additional intake of 5 mg glibenclamide a day in the usual dietetotherapy with clear improvement of the carbohydrate metabolism there appear no changes in the level of the triglycerides, the cholesterol or the beta-lipoproteids in the serum. By means of this a clear effect of the sulfonyl-ureas on the fat metabolism could be proved.