However, the study was "much too small and much too short," states an editorial published with the study in the Annals of Internal Medicine.
Diabetes Drug Study
The researchers included Bernard Zinman, MD, of Mount Sinai Hospital in Toronto. They randomly split the patients into two groups.
Patients in one group were assigned to give themselves two daily injections of Byetta for 16 weeks in addition to the diabetes drugs they were already taking.
For comparison, patients in the other group gave themselves two daily injections of an inactive liquid (placebo) for 16 weeks, in addition to their other diabetes drugs.
None of the patients knew whether they were giving themselves shots of Byetta or the placebo.
At the end of the 16-week study, the patients took hemoglobin A1c tests
During the study, the patients taking Byetta lowered their average hemoglobin A1c level by almost 1 point.
That brought their average hemoglobin A1c level near the upper limit recommended for people with type 2 diabetes.
The Byetta group also lost about 3 pounds during the study, even though the researchers hadn't asked patients in either group to diet, exercise, or make other lifestyle changes.
In comparison, the placebo group didn't improve their average hemoglobin A1c level and didn't change weight in the study.
Byetta Side Effects
Side effects were more common in the Byetta group. The most common side effects were mild-to-moderate nausea and vomiting, which affected about 40% of the patients taking Byetta.
The Byetta group also had a higher percentage of patients who quit the study. Twenty-nine percent of Byetta patients quit the study, compared with 14% of those taking the placebo.
Side effects were the main reason for Byetta patients quitting the study, note the researchers.
Byetta's long-term effects beyond four months aren't addressed in this study.
The study was designed and funded by Byetta's maker, the drug company Eli Lilly and Co. Lilly workers were among the researchers. Lilly is a WebMD sponsor.
The study's small size and short duration leaves many questions unanswered, notes Saul Malozowski, MD, PhD, MBA, in the journal editorial.
Malozowski works at the National Institute of Diabetes and Digestive and Kidney Diseases.
"Among the most important questions are: Will glucose [blood sugar] control last more than [four months]? Who is at greatest risk for adverse drug reactions? Will dose adjustment improve glucose control and decrease adverse drug reactions?" writes Malozowski.
He notes that when the study started, many patients weren't taking the maximal dose of Actos, Avandia, or metformin, and that lifestyle change wasn't part of the study.
"We simple don't know whether patients optimally treated with diabetes education, diet, TZDs (the group of diabetes drugs that includes Actos and Avandia), and metformin will receive as much benefit from [Byetta] as the paper reports," writes Malozowski.