This study was done at the Yokufukai Geriatric Hospital to examine the relationship between Sulfonylureas and the incidence of Myocardial Infarction in 387 cases. The cases were necropsied; they had abnormal glucose intolerance; and they were sixty years or over.<br>I. The incidence of Myocardial infarction (MI) in the Tolbutamide Group (T) was 38.1%, and that in the Sulfonylurea Group (SU), including T, was 40.9%, significantly higher than in the Free Group (F) consisting of dieters alone.<br>The cases were divided into two groups: one with Mild Glucose Intolerance (MGI) and the other with Diabetes Mellitus (DM). In the MGI group, the incidence of MI in T was 40.7%, significantly higher than the 16.1% for F.<br>II. Luminal narrowing of the coronary artery was considered to be the most important factor in the evolution of myocardial ischemic lesions. We studied the relationship between the incidence of MI, the coronary artery system and diabetic therapeutic methods.<br>The left descending, left circumflex and right coronary arteries were dissected at about 5mm intervals. The grade of stenosis was estimated macroscopically and expressed as a luminal narrowing percentage. Cases who had 75% or more arterial stenosis were classified as group A and the others as group B (less than 75% stenosis).<br>1) In group A, the incidence of MI was 52% for T, 55.6% for SU and 34.6% for F. T and SU were significantly higher than in F.<br>In group B, there were no significant differences in the incidence of MI between T, SU and F.<br>2) In MGI and group A, the incidence of MI in T was 57.9%, significantly higher than the 34.4% in F.<br>In DM, it did not change significantly.<br>3) All cases were divided into two groups: those 74 years and under and those 75 years and over.<br>In those 75 years and over and in group A, the incidence of MI in SU was significantly higher than in F. However, in those 74 years and under, there was no significant difference in the incidence of MI between groups SU and F.