First the painkiller Vioxx; now the diabetes drug Avandia. Another big drug safety issue has consumer groups, doctors and congressmen calling for an overhaul of the U.S. Food and Drug Administration.

On Monday, a medical journal published an analysis suggesting that Avandia raised the risk of heart attacks and possibly deaths. More than 6 million people worldwide have taken the drug to control blood sugar since it came on the market eight years ago, and about 1 million Americans use it now.

Cases like this will continue "until we are able to get a better system of drug approval and surveillance," said Dr. Jerry Avorn, a Harvard Medical School professor and author who has criticized the FDA for not watching more closely for problems with drugs.

The consumer group Public Citizen said the FDA has failed to require Avandia's maker to adequately warn about the dangers of the drug. And Consumers Union called on the agency to make results of all consumer drug testing public "so doctors, researchers and patients can more quickly know about a drug's risks."

Pooled results of dozens of studies on nearly 28,000 people revealed a 43 percent higher risk of heart attack for those taking Avandia compared to people taking other diabetes drugs or no diabetes medication, according to the analysis published online Monday by the New England Journal of Medicine.

The findings are frightening because two-thirds of the people with Type 2 diabetes, the most common form, die of heart problems, so a drug that boosts this possibility is especially hazardous for them.

Still, the actual risks to any single patient appear small. Diabetics should talk to their doctors before stopping any medication, said a statement issued by the American Diabetes Association and two groups of heart doctors.

Avandia's maker, British-based GlaxoSmithKline, disputed the results of the analysis but acknowledged that its own similar review found a 30 percent increased risk — information it gave last August and possibly even earlier to the Food and Drug Administration. But the company said that more rigorous studies did not confirm excess risk.

FDA officials issued a safety alert on Monday and said they likely would convene an advisory panel, but planned no immediate changes to the current side effect warnings on the drug's packaging.

Several members of Congress expressed alarm. Rep. Henry Waxman, D-Calif., chairman of the House Committee on Oversight and Government Reform, announced a hearing for June 6 on FDA's role.

Avandia is used to treat Type 2 diabetes, which is linked to obesity and afflicts 18 million Americans and 200 million people worldwide. This form of diabetes occurs when the body does not make enough insulin or cannot effectively use what it manages to produce.

Avandia, or rosiglitazone, helps sensitize the body to insulin and was considered a breakthrough medication for blood sugar control. It also is combined with metformin and sold as Avandamet. Only one other drug like it — pioglitazone, sold as Actos and Actoplus Met by Takeda Pharmaceuticals — is sold in the United States.

About 13 million Avandia prescriptions were filled in the U.S. last year. A one-month supply of Avandia sells for between $90 and $170.