Type 2 diabetes (T2D) is associated with an increased risk of multiple cancers such as colon, breast (for women who went through menopause), pancreatic, liver, endometrium (lining of the uterus), bladder, and non-Hodgkins lymphoma. T2D and cancer share a major risk factor: high body fat. The complete understanding of diabetes and cancer link is still yet to be fully understood.
A study of 45,000 women that began in the 1970s found that women diagnosed with diabetes had a 50% higher chance of developing colorectal cancer compared to women without the disease. T2D patients are insulin resistant which causes the body to increase the production of insulin in an attempt to bring the blood glucose levels down. High insulin levels may be a contributing factor to the higher cancer risk. The full understanding of the diabetes-cancer link is yet to be fully identified.
- Gender: Men are more likely to develop cancer and T2D compared to women.
- Weight: Overweight and obese individuals have a higher risk of cancer compared to lean people. Although losing weight decreases the risk of T2D, it is unclear if weight loss reduces the risk of cancer.
- Diet: Limiting the amount of red meat and increasing the intake of vegetables, fruits, and whole grains have been associated with a lower risk for many types of cancer.
- Exercise: Regular exercise (30 minutes of moderate intensity exercise per day) has been shown to lower the risk of several types of cancer. It also reduces the risk of T2D by 35-36%.
- Smoking: It is associated with several cancers, especially lung cancer. It also increases the risk for T2D and other diabetes complications.
Diabetes Medications & Cancer Risk
Some studies have found links between diabetes medications and cancer, but no definitive link has been found.
- Metformin: Studies have shown that Metformin decreases the risk of cancer and improves survival in those with cancer.
- Thiazolidinediones: Some research suggests that it decreases the risk of some cancer. However, in 2011, the Food and Drug Administration (FDA) added a warning for the possibility of bladder cancer in Pioglitazone.
- Incretin therapies: None have been shown to cancer in humans, but Liraglutide increases the risk of thyroid cancer in rats.
- Insulin: Although it has long been suspected that high insulin levels increase the risk for cancer and diabetes, studies have failed to find hard proof for insulin that is taken as medication.
In trying to reduce the risk of cancer, one should keep in mind the difference of non-modifiable risks and modifiable risks. Non-modifiable risks are factors that cannot be changed, such as gender and age. Modifiable risks are factors that one could alter, such as trying to lead a healthier lifestyle by exercising and eating healthy.
Gebel E. Diabetes and cancer: what’s the connection? Diabetes: The Healthy Living Magazine. 2012. URL Link. Accessed 1/29/2017.