Why Nearly 1 Million Patients Can't Get Diabetes Rx

Metformin restrictions may limit use in diabetes

(RxWiki News) Due to government restrictions, many diabetes patients may be missing out on a common medication that could improve their health.

A new study found that many more people could use a medication called metformin if the US Food and Drug Administration (FDA) would revise its rules for when the medication can be used. However, the FDA limits metformin use in some people who have diabetes because of potential complications.

The FDA says metformin (brand names Glumetza, Fortamet, Riomet and Glucophage) should not be used in people who have both diabetes and kidney problems. Many doctors and medical societies, however, say the FDA is too restrictive.

“The FDA is overdue to revisit the [restriction of] metformin use in patients with mild to moderate [kidney problems], which is worsening the care of almost 1 million patients with type 2 diabetes in the U.S.,” said study author Sean Hennessy, PharmD, PhD, in a press release.

Dr. Hennessy is an associate professor of epidemiology at the University of Pennsylvania's Perelman School of Medicine, and co-author James H. Flory, MD, MSCE, is from the division of Endocrinology at Weill Cornell Medical College.

These researchers examined how metformin use would differ if the rules were relaxed. Dr. Hennessy and team found that nearly 1 million more patients with diabetes would be able to take metformin.

Metformin is a medication used to regulate blood sugar in people who have type 2 diabetes.

Type 2 diabetes occurs when the body does not produce enough insulin. People with type 2 diabetes also become less sensitive to insulin’s effects. Insulin is a hormone that regulates blood sugar.

The stumbling block keeping many patients from using metformin is the patients' kidney function, Drs. Hennessy and Flory found.

Metformin can cause a buildup of a substance called lactic acid, which impaired kidneys cannot remove. Lactic acid buildup can cause kidney failure, severe infections, liver failure and heart failure.

"Diabetics are at risk of developing a lot of long-term complications such as kidney insufficiency/failure, heart disease, congestive heart failure, dehydration from very elevated glucose, infections that can lead to dehydration or lower blood pressure," said Josephine Dlugopolski-Gach, MD, a pediatrician and internist at Loyola University Health System.

"All of these issues can cause decreased blood flow to the kidney and worsening function in a short period of time. If the diabetic patient is on metformin, has borderline kidney function and gets an acute illness, the risk of developing lactic acidosis goes up much more. The initial symptoms of lactic acidosis may be mild and similar to uncontrolled diabetes or viral infection, so it may not be caught until the patient is very sick," said Dr. Dlugopolski-Gach, who was not involved in this study.

"Kidney function does vary from day to day, so if the kidney function is overall good, metformin is safe, and if overall abnormal, metformin is much less safe," she told dailyRx News. "Most diabetics are on multiple medications so the overall picture is the most important factor in keeping the patient safe. Regular follow up appointments and labs are important because things may change within a few months before the patient has any major symptoms."

Doctors assess kidney function with lab tests. The FDA recommends that doctors use a test called the serum creatinine level. Many doctors say a test called the estimated glomerular filtration rate (eGFR) should be used instead. Both lab tests measure kidney function.

The eGFR is a more modern test, and many doctors feel it gives a better picture of how well a patient's kidneys are working. If the FDA based its recommendations on the eGFR test, more patients with diabetes would be able to take metformin, Drs. Hennessy and Flory wrote.

Drs. Hennessy and Flory said the FDA should review and relax its recommendations. Although citizen petitions to relax the restrictions on metformin use were filed in 2012 and 2013, the FDA has not yet responded.

This study was published online Jan. 4 in JAMA Internal Medicine.

Dr. Hennessy received consulting fees, institutional support and educational funding from Bristol-Myers Squibb, AstraZeneca and Novartis. These companies make metformin or other medications used to treat diabetes.

Review Date: 
January 5, 2015