There are many different treatment options available for Type 2 diabetes, ranging from several classes of oral medications, to injectable therapies including insulin.  Metformin is considered in most countries to be the first line treatment for Type 2 diabetes for a long list of reasons, and a recent study adds improved survival after a diagnosis of cancer to this list of metformin-related benefits.

The study, recently published in the journal Diabetes Care, looked at data from over 350 primary care practices in the United Kingdom.  They examined data regarding patients who had a diagnosis of both type 2 diabetes and cancer, and then looked at what diabetes medications these people were prescribed.

The authors found that cancer mortality in this population was 9% higher amongst diabetics, compared to non diabetics.  When they looked at diabetic patients on metformin, they found that the cancer mortality rates were lower compared to patients using sulfonylureas or insulin alone to treat their diabetes, and were also lower than the cancer mortality rates in nondiabetics.  In patients using a combination of metformin + sulfonylurea, or metformin + insulin, the cancer mortality rates were the same as for non diabetics.

So what does this mean?  Firstly, these data further strengthen the position of metformin as first line treatment for type 2 diabetes, and adds to the known benefits of metformin (including improvement in blood sugars, decreased risk of diabetes-related complications, a minor amount of weight loss, doesn’t cause low blood sugars, etc).  It also increases interest in the potential use of metformin as anticancer therapy in patients who don’t have diabetes; in fact, metformin is currently being studied in trials with breast cancer chemotherapy, to treat breast cancer in non diabetics.

In regards to the comparison of metformin with other diabetes medications, we have to be careful of factors that can confound (confuse) these conclusions.  For example, the patient who requires insulin to treat their diabetes is metabolically different than the patient who does not require insulin – those needing insulin are often more insulin resistant, and this very likely has an impact on cancer related risk.   Furthermore, it is often necessary to use a combination of medications to treat diabetes, as metformin is often not enough to control blood sugars in many people.

Control of blood sugars is of paramount importance to the health of diabetics, and for many, multiple medications are needed to maintain blood sugar control.    The take home message from this study is that metformin remains the first line treatment for type 2 diabetes, and should be included as part of the diabetes treatment regimen, provided that the patient tolerates it and does not have any health conditions that would prohibit its use.

Dr Sue Pedersen © 2012 

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