The researchers found that metformin, first approved by the U.S. Food and Drug Administration in 1995 and sold as Glucophage, Riomet and Fortamet, not only controlled blood sugar levels, but also was less likely to cause weight gain.
It was also found to be more likely than other drugs to lower bad cholesterol levels in the blood.
According to the researchers, these health benefits are important because they can potentially ward off heart disease and other life-threatening consequence from diabetes.
"Sometimes newer is not necessarily better," says lead study author Dr. Shari Bolen, an internist at Hopkins.
"Issues like blood sugar levels, weight gain and cost could be significant factors to many patients struggling to stay in good health," says Bolen, an instructor at The Johns Hopkins University School of Medicine.
The scientists say that though all of the commonly used oral medications were equally safe and worked much the same at lowering and controlling blood sugar levels, metformin stands out because it offers the same level of effectiveness without lowering glucose measurements too much, and for a lower price.
They say that the main drawbacks to metformin are digestive problems and diarrhea. Given that previous studies have found evidence that the medication leads to the build-up of lactic acid in the blood in people with moderate kidney or heart disease, the researchers note that it should not be prescribed to anyone with either of these conditions.
"When you are dealing with an epidemic like diabetes, it is important for people to weigh their treatment options with their physician and to make informed decisions about which medication best suits their needs," says Bolen.
During the study, the researchers reviewed the scientific evidence from 216 previous studies and compared each drug for its clinical effectiveness, risks and costs. In addition to metformin, the thiazolidinediones and sulfonylureas, drugs included in their analysis were repaglinide (Prandin), miglitol (Glyset), acarbose (Precose), and nateglinide (Starlix).
The researchers say that further studies are required to compare the long-term effectiveness of one treatment to another, and to compare drug effects on quality of life and life expectancy.
The study has been published in the journal Annals of Internal Medicine.