The RBP4 concentration was 25.4%(31.50 ± 1.28 μg/mL vs. 25.12 ± 1.37 μg/mL) and 25.5%(31.51 ± 1.36 μg/mL vs. 25.12 ± 1.37 μg/mL) higher in shift workers without T2DM and those with T2DM, respectively, compared to day workers with T2DM. This evidence concerns the gene RBP4 and type 2 diabetes mellitus.