By David Liu PHD

Saturday Aug 4, 2012 (foodconsumer.org) -- Having type 2 diabetes mellitus means having high risk for various cancers including pancreatic cancer and breast cancer, according to a new study in MBC Public Health.

The study led by Pian-Hong Zhan of Zhejiang University in Zhejiang China and colleagues showed that people with type 2 diabetes mellitus were nearly three times as likely as those who did not have the disease to develop pancreatic cancer.

The study also found type 2 diabetes mellitus was associated with greatly increased risk for liver cancer, kidney cancer, breast cancer and leukemia although it was not correlated with prostate cancer risk.

The population-based retrospective cohort study was conducted in the Nan-Hu district of Jiaxing city, Zhejiang province, China. Cancer cases among type 2 diabetics were identified from 2002 through 2008 from the Diabetic Surveillance and Registry Database with the Cancer Database.

Here are what the researchers found:

1) Overall, type 2 diabetes mellitus in male and female patients was associated with 33 and 74 percent increased risk of caner, respectively.

2) Type 2 diabetes mellitus in male and female patients was associated with 197 and 169 percent increased risk for pancreatic cancer, respectively.

3) Type 2 diabetes mellitus in male patients was correlated with  54 percent increased risk of liver cancer and 309 percent increased risk for kidney cancer.

4) Type 2 diabetes mellitus in female patients was linked with 121 percent increased risk of breast cancer and 317 percent increased risk for leukemia.

Previous research by the same authors also found that type 2 diabetes mellitus was associated with colorectal cancer (colon cancer, but not rectal cancer), bladder cancer, breast cancer and endometrial cancers.

This is not the first study that establish the association between type 2 diabetes mellitus and risk of various cancers although the mechanism behind the association has remained unclear.  The risk is increased not only by many risk factors shared by both diabetes and cancer, but also something else. 

The common risk factors for both diabetes and cancer include age, obesity, higher intake of saturated fats and refined carbohydrates, sedentary lifestyle, tobacco smoking and some psychology factors, according to the study report.

Hyperinsulinemia and insulin resistance associated with type 2 diabetes mellitus promote the production of  insulin-like growth factor axis  protein 1(IGF-1), which is known to be a potential mitogen and inhibitor of apoptosis and also promote carcinogenesis in animal models.  IGF-1 has been linked to high risk of cancer.

Risk factors affecting the high risk of liver cancer in type 2 diabetes, according to the authors of the study, include the mitogenic action of insulin; liver inflammation; hepatocyte damage and repair; diabetes-related diseases of liver cancer, such as steatosis and cirrhosis; and nonalcoholic fatty liver disease.

Risk factors affecting kidney cancer risk in type 2 diabetes people include hyperinsulinemia and insulin resistance, higher IGF-1 in serum and hypertension.

To prevent cancer, it is a good idea to prevent diabetes in the first place. One thing everyone can do to reduce the risk of diabetes is avoid using too much saturated fat and trans fat, and too much of refined sugars.