In contrast, univariate analysis showed that age 70–80 years (1.14,0 .58–1.70 vs ref), age ≥ 80 years (2.43, 1.52–3.35 vs ref), ASA 3 (3.98, 2.91–5.05 vs ref), Hb group ≥11 to 13 (0.25, 1.07–0.66 vs ref), Hb group < 11 (1.31,2.88–2.09 vs ref), duration of surgery ≥120 min (1.74, 0.78–2.69 vs ref), DM (0.94, 0.44–1.44 vs ref), IHD (1.71, 0.85–2.58 vs ref), CCF (5.90, 3.65–8.14 vs ref), and creatinine > 2 mg/dl (6.53, 4.28–8.77 vs ref) were positively correlated with LOS. This evidence concerns the gene GSTM1 and diabetes mellitus.