Diabetes mellitus and periodontal disease have high incidence in the general population and are associated with various degrees of dysfunction in the immune system. It has been shown that diabetic patients with severe periodontal disease have more complications of diabetes and less effective metabolic control compared with diabetic patients with healthy gingiva. Patients with diabetes and severe periodontal disease present higher levels of serous immunoglobulin A (IgA). Elevation of the IgA1 isotype is thought to contribute to this phenomenon. Another important event in the diabetes-periodontitis association is the disturbance in local and systemic production of inflammatory cytokines.