thats interesting b/c i have Grave’s Disease (the opposite of Hashimotos) and had to have radiation treatment for it. then i developed D, too.
how was the sensor on your lower back? i tried that a few times, but i kept having it fall off whenever i pulled my pants up or down. 
Oh, wow. I’m an autoimmune nightmare - I was diagnosed with Hashi’s over 12 years ago, and then just in the past 3.5 years I’ve been diagnosed with Celiac, LADA, and a mixed connective tissue disease. Have a couple other things that there’s still debate whether or not they’re autoimmune, and a muscle disease thrown in for good measure. 
It wasn’t as terrible as I first thought it would be. I had to be careful when picking up my kiddos and of course putting on/pulling off pants and skirts, but I didn’t have much of an issue with it; it never got pulled off, which is good because I didn’t have anything to help put it back in!
do you use Tegaderm “tape” over your sensor? i had to, otherwise it would just come right off. but the Tegaderm helped a lot. i bought it on Amazon. dont remember what i paid for it, but i wasnt ever able to find it in the drugstores. (also, Dexcom stood by, for insurance purposes, a failed sensor even if you admitted to using the Tagaderm tape)
btw, sooo sorry to hear about all of your autoimmune diseases. i know its a B. its a lot to take on and even a lot more to manage. just from the Graves disease alone, i had to have 3 diff MDs for all diff reasons. i had to have reconstructive eye surgery, too. now, thank god, i just take medication.
pianoplayer, how did your diabetes come to light? did you have a high fasting? a high a1c on a routine physical?
It was discovered through some routine testing when I switched to a new doctor - A1c was only 5.8 and fasting BG 105, but I was positive for GAD antibodies. She said I was “pre-diabetic,” which I later discovered meant the honeymoon phase of LADA.