One of AstraZeneca PLC’s hallmark diabetes drugs is currently under review by U.S. regulators after concerns surfaced over possible dangerous side effects.

The Food and Drug Administration (FDA) is set to review clinical trial data for the drug from AstraZeneca. The drug at the center of the study, saxagliptin, is marketed as Onglyza on its own or in conjunction with Kombilgyze XR, an oral hyperglycemic drug for type 2 diabetes.

Last September, a study called the SAVOR trial was published in the New England Journal of Medicine. The study indicated an increased risk of hospitalization for heart failure for those who used saxagliptin, in comparison with a placebo group. The numbers were 3.5 percent for the group that used saxagliptin, and 2.8 percent in the placebo group. Overall, the study involved 16,492 patients.

The data that was published in the NEJM was based on a study that AstraZeneca and Bristol-Meyers Squibb Co. both supported. The two corporations co-developed the drug, and AstraZeneca bought all the rights to the drug in a deal that was completed in early February 2014.

For patients who received saxagliptin, there was no further indication of any other problems, such as increased rates of death or other cardiovascular risks such as heart attacks or strokes, according to the FDA website.

The FDA plans to have the trial information by early March, at which point it will independently analyze and publicize the findings.

This drug has been approved for use in conjunction with diet and exercise to help reduce blood sugar levels in adults with type 2 diabetes. Saxagliptin works by increasing the amount of insulin that is produced by the body after meals, when blood sugar levels are high.

AstraZenca includes diabetes drugs as one of its five priority growth areas. Analysts anticipate the yearly sales of the Onglyza franchise to go over $1 billion next year, making it one of AstraZeneca’s best-selling drugs. Sales of some of the company’s other products, including Nexium, Crestor and Seroquel, are believed to decline in the next few years due to competition from generic brands.