e13036 Background: This study aimed to investigate the influence of insulin therapy for type 2 diabetes mellitus (T2D) on cancer development. Methods: We evaluated 4780 patients with T2D, treated at our institution, from 1994-2006, after excluding patients with 1) preexisting cancer or cancer within 1 year after T2D registration, 2) renal transplantation, and 3) follow-up period of < 5 years. The following information was collected from the patients’ electronic medical records: age; sex; registered date of T2D and cancer; last visit; use of metformin, insulin, and medications for microvascular complications; and start date of using insulin in the first year after cohort entrance. Insulin users were stratified according to insulin start date and complication as follows: < 3 months with (462 patients) or without complications (526 patients), ≥3 months with complications (852 patients) or without complications (1249 patients). The standardized incidence ratio (SIR) was calculated using the expected age-standardized incidence rate in Korea. The adjusted hazard ratio (AHR) of insulin was estimated for evaluation of all-year cancer risk and time interval of 3 years from cohort entrance. Results: SIR was > 1 in all cancer types except laryngeal and esophageal cancers. The median follow-up was 12 years (interquartile range: 9–15 years), and 679 events occurred. Insulin users had a significantly higher risk of all-time cancer. The patients with insulin use for ≥3 months without complications had a continuously increasing cancer risk 2–3, 4–6, 7–9, 10–12, and 13–15 years from cohort start (AHR [95% confidence interval {CI}]: 2.2 [0.91–5.3], P= 0.081; 2.39 [1.07–5.32], P= 0.0335; 1.98 [1.35–2.9], P= 0.0005; 2.41 [1.52–3.81], P= 0.0002; and 1.6 [0.6–2.83], P= 0.1077, respectively), while the rest did not. This was significantly associated with stomach, colorectal, lung, liver, pancreatic, and bladder cancers (AHR [95% CI]: 6.09 [2.58–14.4], P= 00001; 2.49 [1.22–5.07], P= 01188; 3.36 [1.18–9.51], P= 0.02265; 14.8 [1.97–110], P= 0.0088; 14.6 [1.88–113], P= 0.0103; and 10.4 [2.38–45.6], P= 0.00186, respectively). Conclusions: Incidences of gastrointestinal, lung, and bladder cancers could be increased in new insulin users without complications.
Insulin therapy and colorectal cancer risk among type 2 diabetes mellitus patients: a systemic review and meta-analysis
