Objective The study aims to investigate the relationship between abnormal concentration of serum transforming growth factor β1 (TGF‑β1) and intraoperative adverse cardiovascular event (ACVE) in patients with type 2 diabetes mellitus (T2DM). Methods Ninety‑four patients undergoing elective knee arthroplasty under spinal anesthesia were assigned to diabetes group (non‑peripheral neuropathy) (DM group, n=29), diabetic peripheral neuropathy group (DPN group, n=34) and non‑diabetes group (non‑peripheral neuropathy) (NDM group, n=31). The patients ranged in age from 50 to 79 years, and were not limited to men and women, American Society of Anesthesiologists (ASA) Ⅱ or Ⅲ. Preoperative serum TGF‑β1 concentrations were measured using enzyme‑linked immunosorbent method. The incidence of ACVE in three groups was observed and recorded. To analyze the relationship between serum TGF‑β1 concentration and intraoperative ACVE in diabetic patients. Results The level of serum TGF‑β1 in diabetic patients was significantly higher than that in non‑diabetic patients (P<0.05), and the level of serum TGF‑β1 in diabetic patients with peripheral neuropathy was significantly higher than that in diabetic patients without neuropathy (P<0.05). The incidence of intraoperative ACVE and the serum TGF‑β1 concentrations in the NDM group, DM group and DPN group presented a consistent order as NDM group0.05), when making intra‑group comparisons. Conclusions Diabetes mellitus and diabetic peripheral sensory neuropathy are related to the increase of serum TGF‑β1. The abnormal increase of TGF‑β1 is related to the occurrence of intraoperative ACVE in diabetic patients with peripheral neuropathy. The mechanism of the pathology is worthy to study.