The periodontal health status of 50 adult diabetics and 53 healthy controls was examined. The diabetic group was further divided into three subgroups according to the control of diabetes. Comparison between the entire diabetic group and the control group did not reveal any differences in either the amount of etiologic factors or in the degree of gingival changes. On the other hand when the subgroups of diabetic patients were examined, those with poorly controlled diabetes suffered significantly more from gingival bleeding than those with good or moderate control. The difference in the amount of gingival bleeding between diabetics with poor control and the control group was also statistically significant. The amount of etiologic factors, however, was similar in all the studied diabetic subgroups indicating an independent significance of the degree of control of diabetes. No correlation was found between duration, complications and medication of diabetes and gingival bleeding. The reason for increased bleeding in poorly controlled diabetics could be either inflammation or vascular changes in the gingiva.