Background: Epidemiologic evidence suggests that diabetes increases the risk of various cancers. This study aims to evaluate the incidence of cancer among Korean individuals with and without diabetes and compare the risk between Type 1 and Type 2 diabetes patients.
Methods: This nationwide cohort study of adults aged ≥ 20 years utilized data from the Korean National Health Insurance Service covering preventive health check-ups from 2009 to 2016. A Cox regression model was applied to estimate the risk of overall and site-specific cancers in diabetes patients.
Results: The cohort included 164,434 non-diabetic individuals and 165,822 diabetic patients (1,604 with type 1 diabetes and 164,218 with type 2 diabetes). Over 3,125,427 person-years of follow-up, a total of 39,132 cancer cases were observed in non-diabetic individuals (incidence rate [IR]: 26.86 per 1,000 person-years), 443 cases in patients with type 1 diabetes (IR: 25.30 per 1,000 person-years), and 42,162 cases in patients with type 2 diabetes (IR: 25.51 per 1,000 person-years). The incidence rate of cancer was significantly higher in diabetic patients compared to non-diabetic individuals; however, there was no statistically significant difference between type 1 and type 2 diabetes. The liver, pancreatic, and bile duct cancers have significantly increased risks in both Type 1 and Type 2 diabetes. Stomach, colorectal, and lung cancers are significantly elevated only in Type 2 diabetes. Thyroid cancer shows a significantly lower risk in both Type 1 and Type 2 diabetes. Additionally, ovarian, uterine, breast cancers and kidney, bladder, prostate cancer exhibit a significantly lower risk only in Type 2 diabetes.
Conclusions: Both Type 1 and Type 2 diabetes patients demonstrated a higher overall cancer risk than non-diabetic individuals. However, the nature of the association varied by diabetes type and cancer site. These findings underscore the importance of tailored cancer screening and preventive strategies for diabetic patients.