Merck's ($MRK) Januvia has seen its fair share of competition from generics makers and other diabetes challengers. But now, it could face a new rival on the scene--and it's a device. Boston-based Intarcia is touting data showing its tiny, implantable drug pump beat out Merck's best-seller in a head-to-head trial, reducing a type of hemoglobin linked to diabetes twice as much as Januvia. Story