AL: anastomotic leak, ASA: American Society of Anesthesiologists, DLIA: double-layer intestinal anastomosis, DM: diabetes mellitus, Hb: hemoglobin, HTN: hypertension, ITU: intensive therapy unit, SLIA: single-layer intestinal anastomosis, SNOSE: sequentially numbered, opaque, sealed envelopes, n: number, NG: not given, TPN: total parenteral nutrition. This evidence concerns the gene GSTM1 and diabetes mellitus.