A low s-IgA secretion rate is suspected to be one of these mechanisms; however, previous studies have shown contradictory results.13,14 Branco-de-Almeida et al reported that DM patients had lower mean levels of s-IgA than non-DM patients,13 while Yavuzyilmaz et al reported that DM patients had higher mean levels of s-IgA than healthy controls.14 These studies13,14 used small and limited community samples and failed to control for factors such as age, educational background, smoking, physical activity, or periodontitis, which are now known to be related to both s-IgA secretion and DM.15–17. Here, CD79A is linked to periodontitis.