Comparisons between T2DM and NDM groups showed that the level of salivary BPIFA1 in T2DM individuals with severe periodontitis was significantly lower than that in NDM subjects with severe periodontitis, indicating that salivary BPIFA1 could be regarded as a sensitive biomarker of T2DM, especially in patients with severe periodontitis. The gene discussed is BPIFA1; the disease is periodontitis.