Among the late complications associated to the diabetes mellitus, periodontal disease has been highlighted, and it can be more severe and refractory to treatment than in healthy subjects. OBJECTIVE Determine the prevalence of gingivitis and periodontitis as well as the Community Periodontal Index of Need of Treatment (CPITN) in diabetic population compared with a control one. Analyze the histological characteristics in the gingiva of diabetic patients. METHODS The study sample was made up of 74 control subjects and 70 diabetics. We evaluated the following parameters: gingival status according to the Löe and Silness criterion, probe depth, loss of insertion, gingival recession and Community Periodontal Index of Need of Treatment. We also performed gingival biopsies in 42 diabetic patients and 29 controls for histological studies. RESULTS We found a statistically higher gingivitis index, loss of insertion and gingival recession in diabetic patients compared to the control population, the same not occurring with the probe depth. We did not find significant differences in the CPITN according to the type of diabetes mellitus, metabolic control or disease duration. The biopsy study did not show significant changes in the gingiva of the diabetic patients compared to the control population. CONCLUSIONS The gingivitis index was higher in the diabetic population. After examination of the treatment needs, we observed how the diabetic patients required more complex treatment.