Hi smoss9
Sometimes blood sugar levels can rise in advance of symptoms of a cold or infection. In my personal experience, I've sometimes had blood sugar levels rise without developing symptoms. Was it a cold or infection that my body adequately dealt with? That's been my best guess.
In your case, I'd be looking to get back into the swing of regular exercise.
I'm a type 1 but know that exercise is effective at bringing sugar levels down. When I've had a cold and insulin seems to make no impact on bringing my sugar levels down, I'll think to myself "stuff this" and go for a good walk until the levels do come down -and this seems to be very effective. 30 minutes walk and I can drop down 4 mmol/l sometimes.
The longer you walk, the more you'll use up the glucose stored by your muscles. You may not notice a reduction in sugar levels right away but at some point, your muscles will need to refuel and they'll take glucose from the blood -therefore finally helping to reduce your sugar levels.
Bear with the higher sugar levels for a bit, keep your activity levels up and I'd like to think those levels should start to come back down.
Ed