No significant differences were noted in age, nationality, DM duration, duration of metformin use, diabetic complication (hypertension and diabetic nephropathy), antidiabetic medications (insulin, sodium-glucose cotransporter-2 inhibitors), multivitamins, mean total cholesterol, mean LDL-cholesterol, median HDL-cholesterol, mean glycosylated hemoglobin level, MCV, mean serum creatinine, and eGFR between the VitB12-normal and VitB12-deficient groups (Table 1). This evidence concerns the gene SLC5A2 and diabetes mellitus.