Among 173 OGIB patients, univariate analysis demonstrated that the presence of vascular lesions (P = 0.036), low Hb <9.050 g/dL (P = 0.038), low platelet count <216.50/μL x10E3 (P = 0.038), elevated BUN ≥ 14.80 mg/dl and serum creatinine ≥ 0.80 mg/dl (P = 0.039, 0.013, respectively), low serum albumin <3.30 g/dL (P = 0.0079), and diabetes mellitus (P = 0.029) were associated with a significantly increased risk of active bleeding. The gene discussed is GSTM1; the disease is diabetes mellitus.