I did for a while but then asked to be put back on metfornin. No reason other than preferring the older medication on the grounds that it has been tested and found to be safe over decades.
JANUMET is available as tablets containing sitagliptin phosphate monohydrate and metformin hydrochloride
In addition, the film coating contains the following inactive ingredients: polyvinyl alcohol, polyethylene glycol, talc, titanium dioxide, red iron oxide, and black iron oxide.
Both Metformin and sitagliptin (Januvia) have individually been around long enough for their patents to expire (14 years +?), however in a combined form that may not be the case which means cheap and cheerful generics are not yet available, it can only be made by the company holding the patent and companies with a license. That might explain the cost.