Wells Fargo last night upgraded Tandem Diabetes to Overweight from Equal Weight with a price target of $27, up from $21. The company's pharmacy model is "transformational and de-risking faster than we expected," the analyst tells investors in a research note. Wells says Tandem's pay-as-you-go is tracking better than expected. Management sounded confident in growing U.S. new starts, and its Mobi Tubeless is a "near-term catalyst into an improving margin story," contends the firm. As such, Wells sees an improved risk/reward at current share levels.