OBJECTIVE To evaluate the frequency of periodontal disease in a group of patients with type 1 diabetes mellitus and its relationship with diabetic metabolic control, duration and complications. METHODS A comparison was made of periodontal parameters (plaque index, bleeding index, pocket depth and attachment loss) in a group of diabetic patients versus a group of non-diabetics (n=20). Statistical analysis was performed to evaluate the relationship between periodontal parameters and degree of metabolic control, the duration of the disease and the appearance of complications. RESULTS Diabetics had greater bleeding index (p<0.001), probing pocket depth (p<0.001) and clinical attachment level (p=0.001). Patients diagnosed for diabetes for shorter duration of time (4-7 years) showed bleeding index-disease severity correlation to be 1.760 ± 0.434. CONCLUSIONS Patients with type 1 diabetes have increased periodontal disease susceptibility. Periodontal inflammation is greatly increased in subjects with longer disease course, poor metabolic control and diabetic complications.