The clear winner: metformin, sold as Glucophage and generically for about $100 a year. It works as well as other diabetes pills but does not cause weight gain or too-low blood sugar, the analysis found. It also lowers LDL, or bad cholesterol.
"It looks to be the safest," said Dr. Shari Bolen, a Johns Hopkins University researcher who led the review, which was published online Monday by the Annals of Internal Medicine.
Consumer Reports also published a consumer guide of the results. Besides metformin, it rates glipizide and glimepiride, sold as Amaryl and Glucotrol, as best bets.
"This is truly significant information for the millions of people with diabetes struggling to control their disease, but also struggling with the high cost of their medications," said Gail Shearer, project director of Consumer Reports Best Buy Drugs.
All diabetes pills can cause problems, so patients should pick the medication based on what side effects matter most in their own situation, the guide advises.
Diabetes afflicts more than 18 million Americans, or 7 percent of the population. Most have Type 2, which occurs when the body makes too little insulin or cannot use what it does produce.
The federal Agency for Healthcare Research and Quality commissioned the analysis of diabetes drugs in 2005, long before a study published in May suggested Avandia, made by GlaxoSmithKline PLC, raised the risk of heart attacks. The new analysis says that evidence is insufficient to settle this issue.
The goal was to do the first in-depth comparison of oral medications that have come out in the past decade, in addition to older ones. The report did not evaluate insulin or other injected diabetes drugs.
Researchers reviewed more than 200 published studies and obtained unpublished information from some drug companies and the federal Food and Drug Administration.
Despite heavy marketing for newer drugs, which cost as much as $262 a month, "we didn't find any benefit" unless a patient could not tolerate an older one, Ms. Bolen said.