Paris-based Sanofi (Nasdaq:SNY) is the fastest company to reduce insulin prices. The pharmaceutical behemoth said it would cut  the list price of Lantus (insulin glargine injection) by 78%. Lantus is its most commonly prescribed insulin in the U.S. Moreover, Sanofi will implement a $35 cap on out-of-pocket expenses for users of the insulin. Sanofi has also…