Sanofi sues US company over diabetes drug patent rights

French drugmaker Sanofi said it is suing a US pharmaceuticals company for allegedly infringing the patent on its key insulin treatment as sales of its diabetes drugs are falling.

Sanofi's Lantus insulin drug, a major source of revenue for the French group, is no longer being reimbursed by several top US health insurance companies which have switched to a cheaper competitor.

That pushed sales of the French group's diabetes treatments down by 12 percent in the second quarter.

Sanofi said in a statement late Tuesday that it is suing US-based Mylan for alleged infringement of 18 patents covering the Lantus and the insulin pen SoloStar.

The suit was triggered after Mylan filed a new drug application with the US Food and Drug Administration (FDA) for insulin glargine pre-filled pen and vial drug products, Sanofi said.

Sanofi has already filed two similar patent infringement suits concerning Lantus against US drug giant Merck.

And in 2014, Sanofi also took another US company Eli Lilly over Lantus but the two sides reached an amicable settlement.