Metformin Linked to a Lower Risk of Certain GI Cancers, Study Finds

Key Takeaways
• Metformin is a common type 2 diabetes medication.
• Research suggests that metformin is associated with lower rates of certain GI cancers among people with diabetes.
• More research and clinical trials would be needed to determine whether the drug could be repurposed for cancer prevention and whether it would enefit patients without diabetes.

Metformin is primarily known as a diabetes drug. It’s inexpensive, safe, and effective at lowering blood sugar levels. Recent research suggests that metformin may have the potential to be repurposed for other diseases, including cancer.
Diabetes has been linked to an increased risk of several gastrointestinal cancers, including liver, colorectal, and pancreatic cancers.1A recent systemic review of 166 studies found that metformin was associated with a reduced risk of these three types of cancers among patients with diabetes.

How Might Metformin Protect Against Cancer?
Metformin is a first-line treatment for type 2 diabetes in adults and children aged 10 and above. This medication is usually prescribed along with other blood sugar management strategies, including diet and exercise.2 It hampers glucose production in the liver, increases the amount of glucose taken in by the cells, and increases insulin sensitivity.34

Diabetes has been linked to an increased risk of several cancers, including liver, colorectal, and pancreatic cancers.1
While the exact mechanism is unknown, metformin is believed to inhibit the formulation of glucose from non-carbohydrate sources in the body (gluconeogenesis). Perhaps due to its ability to lower glucose levels and potential anti-inflammatory properties, metformin “creates unfavorable conditions for cancer cells,” said Junaid Arshad, MD, an assistant professor of medicine at the University of Arizona.
Another reason metformin is associated with a lower GI cancer risk is its role in activating an enzyme called AMP-activated protein kinase
(AMPK). Activated AMPK leads to reduced glucose production in the liver and increased glucose uptake in the body’s tissues.4

What’s Next for Metformin Research?
Right now, the strongest evidence in support of metformin’s anti-cancer potential comes from studies in people living with diabetes. If the drug proves to lower GI cancer risk, Arshad said, it would most likely be used in patients with type 2 diabetes—at least to start.
“The next step will be to test the drug in patients with diabetes mellitus, patients with high risk of developing cancers, such as those with a family history and those with high-risk genes,” he added.

If metformin is to be used in people without diabetes, Arshad said a lot more research is required, especially high-quality clinical trials. But the investment could be worth it, especially if the science backs up the theories.