The Food and Drug Administration is reviewing data on the safety of Lantus, a synthetic insulin made by Sanofi-Aventis SA.

The move comes after a recent study raised the possibility the once-a-day insulin slightly increases risk of cancer.

In a statement Wednesday, the FDA says patients should not stop taking their insulin without consulting a doctor because of the risk of serious immediate and long-term complications.

The agency says it is reviewing many sources of safety data for Lantus, including the study published last week indicating the possible cancer risk. The FDA says it is talking with Sanofi-Aventis about whether additional safety studies will be needed.