AstraZeneca Plc's diabetes drug Onglyza may be associated with an increased rate of death, according to a preliminary review of data by the U.S. Food and Drug Administration.

The FDA's report, posted on the agency's website on Friday, comes ahead of an April 14 meeting of an FDA advisory panel to discuss the drug's safety.

A company-sponsored trial of more than 16,000 patients known as SAVOR previously showed patients taking Onglyza, also known as saxagliptin, had an increased risk of hospitalizations due to heart failure.

The agency's analysis found the heart failure risk valid. It also identified a possible increased risk of death from all causes.

The overall trial results did not reveal a higher death risk, but a more detailed analysis examining only patients who took the drug suggests "a significantly increased risk of all-cause mortality," the review found.

The FDA said the causes of death were often "multifactorial" and some patients may have had several serious medical conditions in the days and weeks prior to death.

Still, the FDA said it "is not reassured" by the increased risk "and we do not necessarily view this pattern of variable causes as evidence the mortality signal is due to chance."

In December 2008, the FDA issued guidance requiring drug companies to conduct studies to show that new diabetes drugs do not increase cardiovascular risk compared with current treatments. The guidance was developed amid growing concern about the safety of many diabetes drugs.

Onglyza was approved in 2009.