Eli Lilly & Co and Boehringer Ingelheim should be allowed to claim that their diabetes drug Jardiance cuts the risk of cardiovascular death, an advisory panel to the U.S. Food and Drug Administration concluded.

The FDA is not obliged to follow the advice of its advisory committees but typically does so.

Jardiance, also known as empagliflozin, was approved in 2014 to help lower blood sugar in patients with type 2 diabetes. The companies are seeking approval to claim that it also cuts the risk of death from heart attacks and strokes.

The panelists voted 12-11 to allow the claim that it cuts the risk of cardiovascular death. The panel voted unanimously that it does not add to the risk of cardiovascular problems.

When the FDA approved Jardiance it asked the company to conduct a study to show the drug did not increase the risk of cardiovascular problems.

Results showed the drug cut the combined risk of cardiac death, non-fatal heart attack and non-fatal stroke by 14 percent.

The result was driven by a 38 percent reduction in cardiovascular death. There was no significant reduction in non-fatal heart attacks or non-fatal strokes.

The trial showed an overall reduction in death from any cause of 32 percent.

Panelists wrestled with concerns that the data emerged from a single trial. The FDA typically requires two trials before approving a claim of this nature. Panelists also struggled to make sense of a number of unexplained deaths, which may have distorted the actual result.

Dr. Robert Smith, a professor of medicine at Brown University and chair of the panel, said the mortality data is "very robust," but he was uncertain whether results could be replicated in a second trial.

Analysts on average expect Jardiance sales to reach $3.1 billion by 2021, a figure that partially reflects a bet that the FDA will allow the cardiac death claim, according to a recent report by Seamus Fernandez, an analyst at Leerink.

Jardiance belongs to a new family of treatments called SGLT2 inhibitors that include Johnson & Johnson's $1.3 billion-a-year Invokana and AstraZeneca Plc's Farxiga. Other diabetes drug makers, including Novo Nordisk A/S are also seeking label expansions for heart risk.