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Popular Diabetic Drug has Anti-Cancer Properties

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Having diabetes is not good news. The disorder, even when it is well-controlled, leads to a number of lifelong complications.

Most type 2 diabetics take either insulin or drugs to lower their blood sugar. One of the oldest drugs used to treat type 2 diabetes is metformin.

In 2005, researchers first observed that diabetics who were on this drug had markedly lower rates of certain forms of cancer compared to non-diabetics.

Since then, many other studies have confirmed the cancer-reducing property of metformin. Some of the cancers which have been reduced in diabetics taking metformin include lung and colon cancer.

How metformin does this is not well understood.

Data from a small clinical trial and animal studies suggest that metformin may suppress the precancerous lesions in humans. There is also evidence that metformin may be suppressing the cellular energy mechanisms that help cancer cells multiply.

What is interesting is that unlike chemotherapy or radiation therapy which acts in a nonspecific manner, metformin appears to be more subtle in its action and is relatively non-toxic.

In a small human trial done in Japan, low doses of metformin in non-diabetic patients also led to a significantly decreased number of precancerous growths. At this low dose, metformin did not cause any adverse effects like hypoglycemia, lactic acidosis or diarrhea.

Other related work from Boston also shows that metformin does reduce risk of cancer in animals.

However, to confirm metformin’s role as a chemoprotective drug for cancer will mean evaluating it in double blind, randomized clinical trials. While all of this sounds simple, the biggest hurdle towards more studies is metformin's lack of patent.

This means that no pharmaceutical company will spend millions of dollars to investigate its role as an anti-cancer drug and then discover that almost anyone can sell it at a cheap price.

The only way to overcome this requires funding from private enterprise or from the government, which in today’s economic scenario is very unlikely.


1. Li D. Metformin as an antitumor agent in cancer prevention and treatment. J Diabetes. 2011 Dec;3(4):320-7.
Abstract: http://www.ncbi.nlm.nih.gov/pubmed/21631893

2. Antonoff MB, D'Cunha J. Teaching an old drug new tricks: metformin as a targeted therapy for lung cancer. Semin Thorac Cardiovasc Surg. 2010 Autumn;22(3):195-6.
Abstract: http://www.ncbi.nlm.nih.gov/pubmed/21167452

Reviewed January 23, 2012
by Michele Blacksberg RN
Edited by Jessica Obert

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