Diabetes is associated, generally, with an increased risk of cancer. It is unknown whether diabetes treatment increases cancer risk. The locations of the cancers involved are liver, endometrium, pancreas, colorectum, bladder, and breast. The increased risk of cancer in diabetic patients is true in Western countries as well as in Asian countries, and is thought to be due to the Westernization of lifestyles in Asia.
In diabetes (type 2), patients develop insulin resistance and secondary hyperinsulinemia. Insulin activity may be the cause of increased cancer risk. High insulin levels cause increased mutations. Although the definite reason is not known, it is proposed that the cause is insulin resistance and hyperinsulinemia (high insulin levels).
Hyperglycemia (high blood sugar) increases carcinogenesis (cancer production) and cancer metastasis (cancer spread to different locations) in diabetic patients. Cancers have high concentrations of glucose, allowing positron emission tomography (PET scans) to diagnose cancers. In addition, high sugar levels promote cancers by producing oxidative stress.
Metformin is commonly used for treating diabetes. It has been found to be associated with a lower risk of cancer and cancer mortality in diabetes. Metformin can actually increase cancer apoptosis (natural cell death) and increase the benefit of chemotherapy in early breast cancer. It has also been reported to prevent colon cancer in non-diabetics.
The current global epidemic of diabetes could result in an increased risk of cancer with great cost to economic future of nations. Diabetes prevention is important to avoid a significant increase in cancer incidence. Prevention should be sought through healthy diets, physical activity and increased weight management.
Prostate cancer risk is decreased by diabetes. It is known that prostate cancer is a testosterone-dependent cancer. Men who have diabetes have lower testosterone levels, which may be due to increased insulin resistance. Reduced testosterone levels could explain the reduced risk of prostate cancer in diabetics, in contrast to increased rates of cancer usually seen with diabetes.
CONCLUSION: Further studies are needed on the relationship between hyperglycemia and cancer in order to prevent an epidemic of cancer related to the ongoing increase in diabetes.
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