Wendy L. Bennett, M.D., M.P.H., an assistant professor in the Division of General Internal Medicine at the Johns Hopkins University School of Medicine says:
"Metformin works for most people. It's cheaper, there's a generic form 'it's tried and true.' Our study shows that even though there are all these newer drugs, metformin works just as well and has fewer side effects. Diabetes is an enormous public health problem, and patients have difficult decisions to make about what medications they should be taking. Our study provides good information comparing drugs and can be used to inform those decisions."
New classes of medication for adult-onset diabetes have been approved by the FDA since metformin, but Bennett and her colleagues wanted to know if the newer drugs were any better than the older technology.
First synthesized and found to reduce blood sugar in the 1920s, metformin was forgotten for the next two decades as research shifted to insulin and other antidiabetic drugs. Interest in metformin was rekindled in the late 1940s after several reports that it could reduce blood sugar levels in people, and in 1957, French physician Jean Sterne published the first clinical trial of metformin as a treatment for diabetes. It was introduced to the United Kingdom in 1958, Canada in 1972, and the United States in 1995. Metformin is now believed to be the most widely prescribed antidiabetic drug in the world; in the United States alone, more than 42 million prescriptions were filled in 2009 for its generic formulations.
More than 25 million Americans have type 2 diabetes, and the number of diagnoses have been steadily rising, with 1.9 million new cases diagnosed in 2010. Like many chronic illnesses, diabetes disproportionately affects older people, and its prevalence is higher among racial and ethnic minorities. The annual economic burden of diabetes is an estimated $132 billion and increasing, mostly attributable to costly complications of the disease.
The research team also looked for the first time at the efficacy of two-drug combinations to treat the chronic disease, which has become increasingly common with more than one-third of diabetes patients needing multiple medications. Researchers found that while two drugs worked better than one in those patients whose blood sugar remained poorly controlled on a single medication, there were also side effects associated with adding a second medication.
While most drugs reduced blood sugar similarly, metformin was consistently associated with fewer side effects. Though metformin is associated with increased risk of gastrointestinal side effects, Bennett, an internist, says she finds many of her patients can overcome them by starting with a low dose and taking it with meals, though patients with severe kidney disease may avoid it.
Meanwhile, the new medications, because there are no generic options, are significantly more expensive than older ones. One hundred metformin pills cost about $35.57, or 35 cents a pill, while 30 Januvia pills (a DPP-4 inhibitor) cost $192.52, or $6.42 a pill which is nearly 18 times as much.
"Some of the drugs haven't been on the market long enough to study the long-term effects or even some of the short-term rare side effects, so we need longer studies in patients who are at highest risk for complications."
It remains an open question as to whether patients with type 2 diabetes who have their blood sugar controlled by medication will reduce their chances of having complications associated with the disease, including eye, kidney and nerve diseases.
Source: Annals of Internal Medicine