Endogenous hyperinsulinemia in the context of type 2 diabetes mellitus is potentially associated with an increased risk of colorectal cancer.
Yu-Xiao Yang and colleagues in Philadelphia, USA undertook a study to determine whether insulin therapy might increase the risk of colorectal cancer among type 2 diabetes mellitus patients.
The researchers conducted a retrospective cohort study among all patients with a diagnosis of type 2 diabetes mellitus in the General Practice Research Database from the England.
The research group excluded patients with <3 years of colorectal cancer-free database follow-up after the diabetes diagnosis as well as those insulin users who developed colorectal cancer after <1 year of insulin therapy.
|Colorectal cancer: |
197 per 100,000 person-years in insulin users
124 per 100,000 person-years in type 2 diabetes mellitus patients not receiving insulin.
The researchers then followed the remaining insulin users and the noninsulin-using type 2 diabetic patients, checking for the occurrence of colorectal cancer.
The research team conducted a nested case-control study in order to perform multivariable analysis and also to determine a duration-response effect.
The researchers found that the incidence of colorectal cancer in insulin users was 197 per 100,000 person-years, compared with 124 per 100,000 person-years in type 2 diabetes mellitus patients not receiving insulin.
Dr Yang concluded, "Chronic insulin therapy significantly increases the risk of colorectal cancer among type 2 diabetes mellitus patients."