No drug review system conceived by a human mind is going to catch all unsafe drugs before they get to market. A good one, however, should be able to flag potential problems early, order detailed scientific investigations to assess risks and get important results into the hands of doctors and patients quickly.

As millions of Americans with diabetes have learned, that's not how things have been working at the U.S. Food and Drug Administration.

Last week, the agency announced that it is requiring the packaging of two widely used diabetes drugs — Avandia, made by GlaxoSmithKline; and Actos, made by Takeda — to include so-called black-box warnings. These alerts, printed within heavy black lines, indicate the agency's belief that use of the drug includes a very serious risk of potentially life-threatening side effects.

But the FDA could have informed diabetes patients and their doctors of these risks 16 months ago when one of its drug-safety reviewers advised doing so. Instead, the recommendation of Dr. Rosemary Johann-Liang, who left the agency last week, was ignored. She told a New York Times reporter that she had been overruled by her supervisors.

Dr. Johann-Liang is the fifth FDA drug-safety reviewer we know of who had similar experiences in recent years:

After one reviewer warned that certain antidepressants caused some children to become suicidal, the agency prevented him from speaking to an advisory panel and ordered an independent review of his work. That review concluded he was correct, and black-box warnings have since been added to the labels of those drugs.

Another drug safety reviewer told congressional investigators in 2004 that the agency failed to heed warnings about the blockbuster arthritis drug Vioxx. The manufacturer, Merck & Co., withdrew it from the market that year over concerns it caused heart attacks and strokes.

Yet another reviewer raised questions last year about the safety of an antibiotic called Ketek. The agency warned doctors about the risks only after articles about Ketek's safety popped up in national newspapers.

Part of the FDA's problem overseeing drug safety is its lack of authority. Once a drug has been approved for sale, the FDA has limited authority to order subsequent safety reviews based on its more widespread usage — and no budget to carry them out. The drug companies themselves rarely conduct post-approval safety studies, but they do commission research to see if a drug approved for one purpose might have other uses as well.

An FDA reform bill already approved by the U.S. Senate would give the agency more authority to order safety testing after drugs are approved. It also would provide additional funds for drug safety testing and create an independent advisory panel to help address safety issues. That's a good start.

In one sense, the FDA is a victim of shifting congressional priorities. After years of criticism that the agency was too slow to approve potentially lifesaving new drugs, Congress created a new method for funding the drug approval process in 1992. It allows the pharmaceutical companies themselves to pay so-called user fees for faster reviews of new medicines they would like to bring to market.

User fees from drug companies now account for about one-third of the funding for the FDA's drug safety office. That creates the possibility of conflict between the desire to approve new medications quickly and the need to ensure that drugs really are safe before they're approved.

When drugs are approved as safe for sale and later pulled off the market or branded with black-box warning labels, it's an indication that the FDA has failed to find the right balance between those two missions.

Congress has recognized the need for sweeping reforms at the FDA. When the House takes up the bill approved by the Senate earlier this year, it should boost the FDA's funding for post-marketing research even further and expand the agency's authority to order it.

If we want a strong, independent FDA protecting the safety of our medications, we're going to have to pay for it.