Metformin, the tried-and-true diabetes drug that is prescribed to many type 2s when they are first diagnosed, may decrease the risk of death from cardiovascular disease. That's the conclusion of a meta-analysis by researchers at the Johns Hopkins Bloomberg School of Public Health in Baltimore, Maryland. 

In a meta-analysis, researchers look at many different studies on the same topic in an attempt to detect overall patterns or relationships. In this case, the Johns Hopkins team examined 40 clinical trials of drugs used to treat type 2 diabetes and then compared the incidences of stroke, heart attack, and other cardiovascular problems associated with each drug.

The researchers were careful to use the word "may" when describing metformin's association with a lower risk of death from cardiovascular disease. They said that although they looked at many clinical trials, the data were still insufficient to assert that metformin definitely lowers cardiovascular risks-but the implications were strong that it does. 

They added that while metformin seems to present the least risk for death from cardiovascular disease among type 2 drugs, all other type 2 drugs show no statistically significant cardiovascular benefits or drawbacks.

Even in the case of rosiglitazone (Avandia), which the FDA has implicated in an increased risk for cardiovascular disease and death, the researchers found no "statistically significant" indication that this is in fact true. 

The Johns Hopkins team concluded that while their meta-analysis seemed to reveal no harmful cardiovascular effects from type 2 drugs, the lack of purposeful long-term studies on the drugs prevented them from saying definitively which drugs are safest. (Twenty-seven of the 40 studies they analyzed were a year or less in duration.) 

The team called for "studies of oral diabetes medications with long-term outcomes," adding that "Only long-term trials can provide definitive conclusions regarding the comparative efficacy of oral diabetes medications and long-term risks."