? Falling Out of Remission?

Hi, been a long time since I posted. Snickers went into remission in February 2020. Since then, I check her blood sugar once every 7-10 days or so. Took her to the vet for a checkup and vaccine about 10 days ago, got a urinalysis and bloodwork done. Everything was normal. Checked her blood sugar that day, normal. I think it was about 90 on the Relion Prime. (I haven't updated her chart for ages since she went into remission.)

The last few days she's been really lethargic. Yesterday she ate at around 5:30am, I checked her blood sugar at 7:30am using the Relion and it was 116, the highest it's been since going into remission. Checked again at 9:30am still 116. Checked at 11:30 and it jumped to 157! Checked on my Alpha Trak and it was 241. Even when she was on insulin (Lantus), her numbers were never crazy high, always in the 200s-high 100s.

Took her to the vet. They checked her urine, no glucose in the urine. Rechecked her BG at 10:00pm and was still 157 on the Relion. This morning, about 5:00am, before feeding I checked using the Alpha Trak because that's what my vet will want, and it was 203.

Is the start of her falling out of remission? The vet said sugar shows up pretty fast in the urine, so I guess yesterday would have to be like Day 1 or Day 2 of her falling out? Her vitals read normal. She's not drinking excessively, just excessively tired and not eating like normal. She clearly doesn't feel well, but so far we can't find anything else wrong with her. Oh, we got her X-rayed yesterday too, X-rays were normal regarding intestines, stomach, etc.

Does this sound like she's fallen out of remission, or more like something else is going on? Any thoughts are helpful.

Edited:
She had her teeth cleaned about 6 months ago and also got dental x-rays at the time. Right now, she only has mild tartar buildup.

TL/DR:
Remission since Feb. 2020
Yesterday's blood sugar jumped between 116-157 Relion Prime, 153-241 Alpha Trak
Snickers is not feeling well, lethargic, not eating like normal, but she is not drinking excessively
Urinalysis yesterday showed no glucose in urine

 

Did you get her teeth checked?
An infection can bring them out of remission pretty fast.

 

Hi, yes, her teeth got checked during her visit last week and yesterday. There's some tartar buildup but nothing serious.

 

I'd get her teeth cleaned and get some dental x-rays.

 

Thanks. She had her teeth cleaned and dental X-rays about 6 months ago. There is only mild tartar build up on her teeth right now. Nothing major.