This study was conducted to characterize the frequency of occurrence, extent, age, and sex incidence of Erythrasma in diabetic patients according to the type, duration, and state. A cross-sectional and case-control combined study of 200 diabetic patients and 160 non-diabetic groups visiting the outpatient clinic of Al-Saddar Teaching Hospital, Department of Medicine and Dermatology, from the period of December 2019 to July 2020. About the diabetic group, their ages range from 12-60 years with a mean age of 37.6 years. 148 patients were non-insulin-dependent diabetes mellitus type (NIDDM) and 52 patients were IDDM. Among all the diabetic patients examined by wood’s light to detected Erythrasma infection 34 (17%) were found to be affected, from 26 males (76.5% of the affected) and 8 females (23.5%) were affected. Among the 52 patients with IDDM, 15 (28.8%) were affected and only 19 (12.8%) from the remainder with NIDDM affected. The peak age incidence was found to be in the fourth decade (30-40 y). The predilection site of the lesions appeared to be the groin was 100%. The extensive or generalized form was found only in 3 (8.8%) patients and the least affected site was the toe webs only in 2 (5.9%). The presentation of the patients was found to be asymptomatic in 22 (64.7%), and the color change (red-brown) was found in all of the patients. In the conclusion, the occurrence of Erythrasma in diabetic patients is more frequent than its occurrence in non-diabetic patients. There is a significant association between the occurrence of Erythrasma and the IDDM. The frequency of occurrence of Erythrasma increase with the long duration of DM and more with the uncontrolled DM.