TORONTO - Health Canada is investigating the diabetes drug Lantus after research suggested there may be an increased risk of developing various types of cancer among those taking the medication.

Lantus is a long-acting synthetic insulin similar to human insulin that is used to control blood sugar in people with Type 1 and Type 2 diabetes. It has been marketed in Canada since February 2005 by Sanofi-Aventis.

The U.S. Food and Drug Administration and the European Medicines Agency recently announced they would be reviewing Lantus (insulin glargine) after four studies looked at the potential link between the drug and cancer in diabetics.

"Three of the four studies suggested a very slightly increased risk of cancer associated with use of Lantus, while the fourth study found no link between the drug and the development of cancer," Health Canada said in an advisory Thursday.

In all studies - published in Diabetologia - the number of patients who developed cancer was small.

Health Canada has not concluded there is a relationship between Lantus and the development of cancer. The department is currently assessing available safety data, including the studies, to better understand any possible risk.

Patients should not stop taking the insulin therapy without first consulting their physician, as uncontrolled blood sugar can have immediate and long-term serious health effects.

Any adverse reactions associated with the use of Lantus can be reported to the  or by calling toll-free 1-866-234-2345.