Prostate Cancer and Diabetes Connection

Diabetes is a chronic condition in which the body’s blood sugar is too high. Your body’s blood sugar is regulated by a hormone called insulin that is made in the pancreas. In some cases, the body mistakes insulin-making cells for foreign invaders and destroys them, reducing or completely stopping your ability to make insulin. This is called Type 1 Diabetes. In other cases, the body may still make insulin as normal, but the insulin isn’t being used correctly, leading to problems regulating blood sugar. This is called Type 2 Diabetes, or T2D. Individuals with diabetes can develop cardiovascular conditions, including heart disease and stroke, as well as nerve damage, among other issues.1 Roughly 12% of men worldwide have diabetes, with T2D making up between 90-95% of these cases.2

Diabetes has been linked to an increased risk of developing cancers including pancreas, liver, and breast cancer, however, the connection between prostate cancer and diabetes is currently less understood.2 Essentially, a fair amount of research has indicated that the risk of prostate cancer is reduced for individuals who have diabetes, specifically T2D, however, factors associated with diabetes, such as obesity, are often linked to an increased risk of developing prostate cancer.3 Further investigating this connection is important at this time, as we are in an obesity epidemic worldwide, and the number of diabetes cases is expected to increase by 20% in developed countries and 69% in developing countries over the next 20 years.3

What does the research say?

Specifically, studies have estimated that the risk of developing prostate cancer is reduced by roughly 15% for males who have diabetes.2,3 One study showed the risk of developing aggressive prostate cancer in individuals with diabetes may even be reduced by up to 30%.3 This decrease in risk has even been consistent amongst various racial and ethnic groups.4 Further, the highest reduction in risk has been reported in individuals who have been diagnosed with diabetes for multiple years, or who have a strong familial history of diabetes (specifically T2D), as opposed to their newly diagnosed counterparts, or those who do not have a family history of T2D.3,5 To further confuse the picture, although diabetes may lead to a decreased risk of prostate cancer, individuals with both conditions have been reported to have worse overall outcomes, including an increase in all-cause death.3

What’s missing?

A huge component missing from many of these studies is why this relationship occurs. With evidence of familial history playing a role in risk reduction, some researchers have suggested a genetic component to the apparent connection, while others have proposed that certain signaling pathways characteristic of long-term diabetes could reduce the amount of androgens made, including testosterone.2,3,5 Androgens play a key role in fueling cell growth and development, including prostate cancer cells. Some researchers have targeted exhausted beta-cells in the body that stop making insulin in T2D, while others have suggested the link may be caused by changes in the body’s inflammatory processes.2,3

There are also confounding factors to consider when looking at these results. For example, diabetes can affect a man’s PSA (prostate-specific antigen) level in the blood. The PSA test is a common screening method to determine if a man should undergo further diagnostic procedures, including prostate biopsy. If a diabetic man is testing at a normal or low PSA level, no further screenings may be given, but the man could in fact have prostate cancer. This could lead to under-diagnosis of the condition in diabetic men, falsely contributing to the decreased risk.6 One study tried to study this confounding factor, and found that if all diabetic men undergo the next level of prostate cancer screening, regardless of their PSA test result, a similar incidence of prostate cancer cases are found in both diabetics and non-diabetics.7

Overall, much more research needs to be done to understand the link between diabetes and prostate cancer diagnosis, and to determine how or why the connection exists.

Diabetes and hormone therapy

One other aspect to consider when thinking about diabetes and prostate cancer is not just diabetes increasing the risk of prostate cancer, but rather, certain prostate cancer treatments, increasing the risk of developing diabetes. Much more research needs to be carried out to understand this link as well, however, hormone therapy, a common treatment option for prostate cancer is designed to dramatically reduce, or even deplete, testosterone levels in the body. This decrease can affect how your body responds to insulin and stores fat. For this reason, the risk of developing diabetes while on hormone therapy for prostate cancer is thought to be increased. Patients may be placed on steroids while being treated for prostate cancer, which may increase blood sugar levels. If you are taking hormone therapy or steroids, it is important to maintain a healthy weight, eat a balanced diet, and participate in regular physical activity to decrease and monitor your risk of developing diabetes.8

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