For the 200 million diabetics worldwide, the past few years have brought some disturbing findings about risks that may be associated with certain diabetes drugs. Recent concerns that Avandia (rosiglitazone) might cause cardiovascular problems, for example, have led some experts to call for it to be pulled from the market, although it remains available today. And in late June, studies published online by the journal Diabetologia raised questions about a possible link between the diabetes medication Lantus (insulin glargine) and an increased risk of cancer.
The safety worries about these diabetes medications come from scientific studies of varying designs. Some of the research, like that on Lantus and cancer, is based on observational data, which is not always reliable. The concern about Avandia, on the other hand, comes from clinical trials, which are the gold standard of research, and meta-analyses.
The key thing to remember is not to panic when you hear news of safety concerns about a medication you're taking—and definitely don't quit taking a prescribed diabetes drug without asking your doctor first. "Be sure you talk to your healthcare professional before you stop taking any diabetes medication," says Ann Albright, director of the division of diabetes translation at the Centers for Disease Control and Prevention. "You've got to be sure you're keeping your blood sugar and cholesterol" and blood pressure levels under control, she says.
Indeed, the Food and Drug Administration, the American Diabetes Association, and the American Association of Clinical Endocrinologists offered similar advice in response to the recently released studies on Lantus. Here's a look at the concerns raised about cancer risk, as well as four other risks that some experts in the past few years have mentioned about the diabetes drugs Avandia and Actos.
Cancer. The journal Diabetologia recently published four observational studies on its website. Three of those studies suggested a possible increased risk for cancer in those taking Lantus. The studies examined large patient databases, which should add to their reliability. However, inconsistencies among the studies have led experts to doubt whether there truly is an association between Lantus and cancer, the FDA says. The agency is now looking into safety data from these studies and previously completed clinical trials to determine whether such a risk exists. Sanofi-Aventis, the maker of Lantus, says it will continue to monitor the safety of Lantus and will work with the FDA and other regulatory agencies.
"These are provocative studies, but they're really nonconclusive," says Paul Robertson, president for medicine and science at the American Diabetes Association. "It's something that we have to take seriously, but there's just no consensus." Lantus is widely used, he added, and is considered to be a "very useful, very effective drug." Sanofi-Aventis contributes funding for the ADA's professional, patient, and consumer education programs.
Heart problems. The latest trial to investigate Avandia's cardiovascular risk was the RECORD study, which was published in June in the Lancet. In that trial, as in previous research, Avandia seemed to increase the risk of heart failure. The labels for both Avandia and Actos contain warnings that the drugs may cause or exacerbate congestive heart failure in certain patients.
Some studies, but not all, also link Avandia to cardiovascular risks such as heart attack and death. (Avandia's label describes research linking the drug to risk of heart attack.) A 2007 meta-analysis, which was published in the New England Journal of Medicine and prompted the flurry of concern about Avandia, found that people taking Avandia had a higher risk of heart attack and death from cardiovascular causes. But the recently reported RECORD trial, which was sponsored by Avandia manufacturer GlaxoSmithKline, found that taking Avandia did not seem to up the risk of heart attack or death. And another study, published in November in the Archives of Internal Medicine, found that the risk of death and heart failure for older people with diabetes seems to be greater in those taking Avandia than in those taking Actos (pioglitazone), another medication in the same class.