Shares of Sanofi-Aventis, the Paris-based drugmaker slumped Friday after analysts posted raised concerns that one of the company’s high-selling drugs could have potential health risks.

In trading, Sanofi-Aventis fell 8.2%, the most in seven months, after reports leaked that Lantus diabetes treatment could have suggested links to cancer.

"Recent market questions on the safety of insulin analogues in undisclosed studies,” a UBS AG report cited prior to the drop in sales.

Lantus, Sanofi’s fastest-growing drug last year, and third-biggest-selling drug, is an injected form of insulin used to maintain blood sugar levels in diabetics.

It was approved for sale in the U.S. in 2000 and helped the company’s first-quarter earnings exceed analyst expectations.

“Our information is that indeed a study is likely to be published soon raising the possibility of a link between Lantus use and a certain cancer type,” Sanford Bernstein analyst Tim Anderson said in a research note. “It will be the first time that such a high profile analysis has been published linking the drug to cancer in humans.”

According to UBS, Lantus will most likely make up to a third of profit for the company by 2013.

“Patient safety is the top priority for Sanofi-Aventis and all our products are monitored continuously,” Sanofi-Avents said in a statement released to FOXBuisness.com. “Data from clinical studies involving over 70,000 patients as well as data from post marketing surveillance covering 24 million patient years of experience confirm the safety profile of Lantus.”

Sanofi is betting on Lantus to offset sales declines caused by competition to other drugs.