Shinjo T, et al. - Researchers evaluated the prevalence of periodontitis in a subset of the Medalist cohort and its associations according to the CDC/AAP classification to different criteria of periodontitis and diabetic complications in this cross-sectional study. For diabetic patients of similar ages, the prevalence of severe periodontitis in Medalists was only 13.5% lower than reported levels. Periodontal parameters, including probing bleeding, plaque index, gingival index and demographic traits, including male sex, chronological age, and diagnostic age, were significantly related to periodontitis severity, which was not linked to the duration of diabetes, hemoglobin A1c, body mass index, and lipid profiles. Random serum C-peptide levels inversely related to the severity of periodontitis, lower probing depth and clinical attachment loss. Prevalence of cardiovascular diseases (CVD) and systemic inflammatory markers, plasma IL-6 and serum IgG titer against Porphyromonas gingivalis (P. gingivalis) positively linked to the severity of periodontitis. CVD, serum IL-6 and high-sensitivity C-reactive protein correlated positively and significantly with antibody titer to P. gingivalis. Findings suggested that some Medalists could be protected even with hyperglycemia from severe periodontitis. Endogenous protective factors for periodontitis may be associated with the production of residual insulin and lower levels of chronic inflammation.