The Use of Metformin and Postoperative Insulin Pump Were Predictive Factors for Outcomes of Diabetic Colorectal Cancer Patients after Surgery.

Purpose: This present study aims to explore the influence of metformin and postoperative insulin pump use on colorectal cancer (CRC) patients with type II diabetes mellitus (T2DM) who received surgery in terms of short-term and long-term outcomes.

Methods: 613 CRC patients who had comorbid T2DM and received surgery at a single clinical center from Jan, 2011 to Dec, 2021 were included in this study. Univariate and multivariate logistic regression analyses were used to find predictive factors for overall complications and major complications. Cox regression analyses was used to find prognostic factors for overall survival (OS) and disease-free survival (DFS). All statistical analysis was performed using SPSS (version 22.0) software. The Kaplan-Meier curve was used to show the OS and DFS between the insulin pump group and the no insulin pump group.

Results: Multivariate logistic regression analysis reported that lower body mass index (BMI) ( < 0.01, OR = 0.922, 95% CI = 0.870-0.977) and metformin use ( = 0.03, OR = 0.643, 95% CI = 0.431-0.959) were independent protective factors for overall complications, and insulin pump after surgery ( < 0.01, OR = 3.991, 95% CI = 2.434-6.544) was an independent risk factor for overall complications. As for major complications, metformin use ( = 0.042, OR = 0.274, 95% CI = 0.079-0.956) and insulin pump after surgery ( = 0.03, OR = 2.892, 95% CI = 1.107-7.552) remained independent protective factors and independent risk factors, respectively. Moreover, in Cox regression analyses, age (OS:  < 0.01, HR = 1.032, 95% CI = 1.008-1.057; DFS:  < 0.01, HR = 1.030, 95% CI = 1.008-1.052), tumor stage (OS:  < 0.01, HR = 1.709, 95% CI = 1.244-2.346; DFS:  < 0.01, HR = 1.696, 95% CI = 1.276-2.254), and Insulin pump after surgery (OS:  < 0.01, HR = 2.923, 95% CI = 1.887-4.527; DFS:  < 0.01, HR = 2.671, 95% CI = 1.779-4.009) were independent prognostic factors for both OS and DFS. After comparing the OS and DFS between the insulin pump group and the no insulin pump group, patients who received postoperative insulin pump had worse OS and DFS in all tumor node metastasis (TNM) stages ( < 0.01).

Conclusion: Diabetic CRC patients who used metformin had a lower risk of postoperative complications. However, there was no difference from patients not using metformin in terms of survival. Furthermore, patients receiving postoperative insulin pump had more postoperative complications and worse survival in all TNM stages.