July 1 (HealthDay News) -- Despite recent studies suggesting that the injected diabetes drug Lantus (insulin glargine) might boost cancer risk, the U.S. Food and Drug Administration on Wednesday urged patients who are on the medication to continue using it.

Three of four studies published last Friday in Diabetologia showed a potential link between Lantus -- an insulin analogue made by French drug company Sanofi-aventis -- and increased risks for various tumor types.

But, "the duration of patient follow-up in all four studies was shorter than what is generally considered necessary to evaluate for cancer risk from drug exposure," the FDA said in its first comment on the issue. "Further, inconsistencies in findings within and across individual studies raise concerns as to whether an association between the use of insulin glargine and cancer truly exists."

The agency also believes that differences in the various types of patients selected for each study may have swayed the results.

"Based on the currently available data, the FDA recommends that patients should not stop taking their insulin therapy without consulting a physician, since uncontrolled blood sugar levels can have both immediate and long-term serious adverse effects," the agency wrote.

A statement released Friday by the American Diabetes Association echoed the FDA's position. "For patients using glargine and considering switching to another form of insulin, the data in these studies make it unclear as to whether any one type of insulin increases the risk of cancer more than other types of insulin," the ADA said. "Patients concerned about these studies or their insulin regimen should talk to their doctor and should not stop taking their insulin on the basis of the findings reported here."

Lantus is an "analogue," or artificial version, of insulin and is used by both type 1 and type 2 diabetics to help control blood sugar over an extended period of time. It is given by injection once daily.

The FDA says it is "currently reviewing many sources of safety data for Lantus," including completed and ongoing observational and clinical trials, and may ask Sanofi to conduct further trials should they be deemed necessary.

According to the Wall Street Journal, a spokesman for Sanofi said that the company is working with the FDA on this issue and continues to stand behind the drug's safety.

In the meantime, the FDA says it "encourages both health care professionals and patients to report side effects from the use of insulin glargine to the FDA's MedWatch Adverse Event Reporting Program."

SOURCES: July 1, 2009, statement, U.S. Food and Drug Administration; June 26, 2009, statement, American Diabetes Association; Wall Street Journal