Prostate Cancer and Diabetes Connection

Diabetes has been linked to an increased risk of developing certain cancers including pancreatic, liver, and breast cancer. However, the connection between prostate cancer and diabetes is not well understood.

What is diabetes?

Diabetes is a chronic condition in which the body’s blood sugar is too high. Blood sugar is controlled by a hormone called insulin, which is made in the pancreas. In some cases, the body mistakes insulin-making cells for foreign invaders and destroys them. This reduces or stops your ability to make insulin and is called type 1 diabetes.1

In other cases, the body may still make insulin, but the insulin is not functioning correctly. This leads to high blood sugar and is called type 2 diabetes.2

People with diabetes may have heart problems, including heart disease and stroke. They may also develop other complications, including nerve damage (neuropathy), kidney disease, and eye damage.1

About 14 percent of men in the United States have diabetes. Type 2 diabetes makes up between 90 to 95 percent of these cases.2

What does the research say?

There is conflicting research on how likely people with type 2 diabetes are to develop prostate cancer. Some factors linked to diabetes, such as obesity, are also linked to an uncertain overall risk of developing prostate cancer. However, some research suggests obesity may decrease the chance of developing slow-growing prostate cancer and may increase the chance of developing prostate cancer that grows faster. This has created an unclear understanding of the connection between prostate cancer and diabetes.3,4

On one hand, some studies have found that men who have diabetes may be up to roughly 15 percent less likely to develop prostate cancer. This observed reduced risk was consistent among men of various racial and ethnic groups. Further, the risk was even lower in men who had diabetes for many years or those who had a strong family history of type 2 diabetes.4-7

However, other studies have found that people with uncontrolled, high blood sugar levels may have an increased risk of developing prostate cancer. There are conflicting opinions about whether taking diabetes drugs can reduce this risk or not. Studies suggest that diabetes drugs may impact prostate-specific antigen (PSA) levels and reduce the number of prostate biopsies. This may lead to falsely low prostate cancer diagnoses in men with diabetes.3,8

How are prostate cancer and diabetes connected?

While there is conflicting research, there are some common theories about the possible link between prostate cancer and diabetes.

Some experts believe there is a genetic or inflammatory factor that links the conditions. Others believe that diabetes’ impact on testosterone may be a factor. That is because inflammation and hormones like testosterone play key roles in fueling cell growth, including prostate cancer cells.3,5-7

Researchers have also suggested that diabetes drugs may impact cancer development. However, one study found no link between the two.8

There is no clear data on how or if diabetes impacts prostate cancer screening. The PSA test is a common screening tool used to look for signs of prostate cancer. Men with high PSA levels may need to undergo further tests, including prostate biopsy.3,8

In most cases, men with normal or low PSA levels are not given further tests. However, research shows that PSA levels are often lower in men with diabetes, even when they may in fact have prostate cancer. This may lead to the underdiagnosis of prostate cancer in men with diabetes. This may also falsely contribute to the statistics that show men with diabetes are less likely to develop prostate cancer.3,8,9

Diabetes and hormone therapy

Hormone therapy treatments for prostate cancer may be another factor in the connection between the condition and diabetes.

Hormone therapy for prostate cancer lowers testosterone levels, which causes prostate cancer cells to die or grow more slowly. However, low testosterone levels may affect how the body responds to insulin and stores fat. This explains why some researchers believe that people on hormone therapy may have an increased risk of developing diabetes.10

Steroids may also be used to treat prostate cancer, which can increase blood sugar levels. If you are taking hormone therapy or steroids, maintaining a healthy weight, eating a balanced diet, and participating in regular physical activity are important things you can do to try to lower your risk of diabetes.10

More research is needed to better understand the link between prostate cancer and diabetes. If you have questions about your risk for both conditions, talk to your doctor.

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Written by: Casey Hribar | Last reviewed: February 2021