Poorly controlled type II diabetes mellitus significantly enhances postoperative chemoresistance in patients with stage III colon cancer.

Background: Type II diabetes mellitus (T2DM) has been associated with increased risk of colon cancer (CC) and worse prognosis in patients with metastases. The effects of T2DM on postoperative chemoresistance rate (CRR) and long-term disease-free survival (DFS) and overall survival (OS) in patients with stage III CC who receive curative resection remain controversial.

Aim: To investigate whether T2DM or glycemic control is associated with worse postoperative survival outcomes in stage III CC.

Methods: This retrospective cohort study included 278 patients aged 40-75 years who underwent surgery for stage III CC from 2018 to 2021. Based on preoperative T2DM history, the patients were categorized into non-DM (n = 160) and DM groups (n = 118). The latter was further divided into well-controlled (n = 73) and poorly controlled (n = 45) groups depending on the status of glycemic control. DFS, OS, and CRR were compared between the groups and Cox regression analysis was used to identify risk factors.

Results: Patients in the DM and non-DM groups demonstrated similar DFS, OS, and CRR (DFS: 72.03% vs 78.75%, P = 0.178; OS: 81.36% vs 83.12%, P = 0.638; CRR: 14.41% vs 7.5%, P = 0.063). Poorly controlled DM was associated with a significantly worse prognosis and higher CRR than well-controlled DM (DFS: 62.22% vs 78.07%, P = 0.021; OS: 71.11% vs 87.67%, P = 0.011; CRR: 24.40% vs 8.22%, P = 0.015). High preoperative fasting plasma glucose [DFS: Hazard ratio (HR) = 2.684, P < 0.001; OS: HR = 2.105, P = 0.019; CRR: HR = 2.214, P = 0.005] and glycosylated hemoglobin levels (DFS: HR = 2.344, P = 0.006; OS: HR = 2.119, P = 0.021; CRR: HR = 2.449, P = 0.009) indicated significantly poor prognosis and high CRR, while T2DM history did not (DFS: HR = 1.178, P = 0.327; OS: HR = 0.933, P = 0.739; CRR: HR = 0.997, P = 0.581).

Conclusion: Increased preoperative fasting plasma glucose and glycosylated hemoglobin levels, but not T2DM history, were identified as risk factors associated with poor postoperative outcomes and high CRR in patients with stage III CC.