I have done this the past few years, and with cgm, pump and insulin, it has always come out net lower with using insurance. I always meet deductible within 6-7 months. Last year my 3 day hospital stay by itself maxed me out, so essentially all other cgm, pump, meds were 100% covered. Depends on how you look at it. Always using insurance means I know upfront what max will be.
This year I learned my dexcom can be purchased via pharmacy, and will switch to that for next order, so even better, with cost similar to cash/coupon cost and will apply to insurance.