These discrepancies in findings may be explained by variations in saliva collection methods (stimulated vs. unstimulated), disease stages, genetic susceptibility, or study design and measuring methods, e.g., the inclusion of three groups (uncontrolled T2DM, controlled T2DM, and healthy participants) vs. two groups (diabetic and non-diabetic participants) as study populations, or the use of ELISA method to measure s-IgA vs. immunoturbidimetric or immunonephelometric methods. This evidence concerns the gene CD79A and type 2 diabetes mellitus.