T1D myself for 58 years, diagnosed at 19, checked into Dexcom viability some months ago. Talking with Dexcom reps, they confirmed the price[in the $1000s for the device] and confirmed my insurance would not cover it at all. I discarded the idea---Lifescan One-Touch is much less expensive and I have used it for many years.
Dexcom technology is elegant, incorporates some JNJ insulin pump technology as well if wanted. Too expensive w/o insurance.
Re flu shots: Have been getting them for as long as I can remember, usually in late Sept./early Oct. Got mine yesterday as did my M.D. wife, 20 years younger than me.No AEs. No flu. Invaluable for international travel.