Old Diabetes Drug Has Advantages

July 16, 2007 -- Most type 2 diabetes drugs are equally effective for lowering blood sugar, but the generic drug metformin has fewer side effects than several newer, pricier medications, a government report finds.

Metformin users are less likely to gain weight than type 2 diabetes patients who take Avandia, Actos, or other newer medications, researchers concluded, and they are more likely to show improvements in so-called "bad" cholesterol.

The report was issued by the Agency for Healthcare Research and Quality (AHRQ), a division of the Department of Health and Human Services.

Researchers from Johns Hopkins University’s Evidence-based Practices Center reviewed 216 previously published studies in their effort to compare the effectiveness, risks, and costs of older and newer diabetes pills.

The study, which was made public today, will appear in the Sept. 18 issue of the Annals of Internal Medicine.

Diabetes Drugs: Old and New

All diabetes medications help to lower blood sugar, but they work in different ways. Metformin and drugs in the class known as sulfonylureas, such as Glipizide or Glyburide, are among the least-expensive oral diabetes medications because generic versions are now available.

The newer oral medications Avandia (by GlaxoSmithKline) and Actos (by Takeda Pharmaceuticals) -- both in the drug class thiazolidinedione (TDZ) -- are now among the most widely prescribed diabetes drugs.

Among the highlights of the report:

• Metformin was one of the few diabetes drugs not associated with an increase in weight. The report noted that other widely prescribed diabetes drugs have been shown to increase body weight by an average of 2 to 11 pounds.
• Use of metformin was associated with a decrease in blood levels of low-density lipoprotein, or "bad" cholesterol, while use of the TDZ class of drugs raised levels good cholesterol and had a harmful effect on LDL "bad" cholesterol.
• Amaryl, Glucotrol, and other sulfonylurea drugs were more likely to cause unsafe drops in blood sugar (hypoglycemia) than other diabetes drugs.
• Patients on metformin or the drug acarbose complained of diarrhea and other gastrointestinal problems more than users of other drugs. Patients who took only metformin were more likely to experience these digestive problems than patients who took lower doses of metformin in combination with other diabetes drugs.
• Use of Avandia and Actos was associated with a greater risk of congestive heart failure.

Diabetes Drugs and the Heart

Concerns about heart failure risk led the FDA to announce last month that labels for Avandia and Actos will soon carry a "black box" warning to alert doctors and patients to the risk. A highly publicized study recently linked Avandia to an increased risk of death from heart attacks, but the drug's manufacturer has challenged the findings.

In testimony before a congressional committee in June, a GlaxoSmithKline spokesman said there is no evidence that Avandia carries more heart risk than other drugs of its class. And an interim report from an ongoing company-sponsored study assessing Avandia's impact on the heart found the data on heart attack risk to be inconclusive.