Cystatin C, CD26, and CD14 proteins have been widely described in serum and plasma of individuals with disorders such as diabetes, cardiovascular diseases, and kidney failure, among others  (Yamamoto et al., 2013; Chung et al., 2018; De et al., 2018; Röhrborn, Wronkowitz & Eckel, 2015; Reiner et al., 2013). This evidence concerns the gene DPP4 and diabetes mellitus.