Obesity and diabetesPatients with long-term type 2 diabetes and obesity are more likely to develop colon cancer, a study has found.  The risk is 1.2 to 1.3 times greater with a duration of obesity of four years or more, based on an analysis of data on more than 300,000 adults with diabetes and a control group.The research - published in the journal Diabetes Care, researchers from the Utrecht University Institute of Pharmaceutical Sciences in Utrecht, the Netherlands - sought to investigate the risk of colorectal cancer in patients with type 2 diabetes and to assess whether treatment stage and duration of obesity affect that risk.

The study identified 2,759 patients with type 2 diabetes and colorectal cancer after a median follow-up of 4.5 years from the Clinical Practice Research Datalink. All patients were on at least one prescription drug for type 2 diabetes.

Results showed that type 2 diabetes was linked with a 1.3-fold increased risk for developing colorectal cancer (HR = 1.26; 95% CI: 1.18 - 1.33).

There was no association between treatment stages and colorectal cancer risk, but patients with obesity for 4 to 8 years (HR = 1.19; 95% CI: 1.06 - 1.34) and those with obesity for more than 8 years (HR = 1.28; 95% CI: 1.11 - 1.49) had a significantly increased risk of colorectal cancer.

The findings suggest that patients with type 2 diabetes, especially those who have been obese for 4 or more years, have an increased risk for developing colorectal cancer.