Furthermore, independent risk factors for VitB12 deficiency in metformin-treated patients with tbl2DM include daily dose of metformin >2000 mg, male gender, high BMI, smoking, low hemoglobin, high fasting blood glucose, and concomitant use of sulfonylurea, dipeptidyl peptidase-4 inhibitor, and H2 blockers/PPI (Table 3). The gene discussed is DPP4; the disease is hyperinsulinemic hypoglycemia, familial, 4.