French drug maker Sanofi saw its stock price plunge Tuesday after it reported a slide in quarterly earnings and warned of pricing pressure on its blockbuster diabetes treatment in the U.S. Net profit slipped 2.4 percent in the third quarter as the maker of the Lantus diabetes treatment booked a higher charge for restructuring at its French operations. The drugmaker reported net profit of 1.9 billion euros in the third quarter, down from 1.22 billion euros a year earlier.