I am diabetic. 12 years now. But very mildly diabetic and pretty careful with my diet & meds. Exercise not so much any more. Sigh.
If I take a reading immediately post-wakeup but pre-coffee, they average about like yours: 100-105. But over the course of two weeks, the lowest will be 70ish and the highest will be 115ish. The point being the daily spread is large even though the average is quite consistent over months & years. And this for readings taken at a very consistent point in the physiological day.
I would place little value on your two readings taken 10 months apart and both taken fasting, but also taken partway into your day’s activities. IOW, my take on your situation is to believe the A1C, not those two FBG readings.
FWIW, late onset diabetes is a disease where you slowly burn up your pancreas by forcing it to overwork. Eventually as it wears out and dies off what’s left can’t handle the needs of your daily living and then the trouble really begins. The opportunity for early warning is not when your A1C starts rising, but rather when your post-prandial BG spikes are larger and last longer than they should. That’s the sign of a pancreas running flat out and not keeping up; taking 3 hours to do a 1 hour job. And those extra two hours of sprinting are what’s killing it. So your goal is to find out if you’re making it sprint, then if so, stop that through diet, exercise, weight loss, and, if necessary, meds. Like your heart, it can jog along 70 years no problem. Just don’t make it sprint several hours a day.
I’m thinking that your one meal a day plan is probably contributing to overwork. Especially if that meal is carby or sweet. Which a standard American meal is quite likely to be, even if it seems pretty innocuous or healthy compared to a beer & pizza horror show.
If I was going to pursue fingerprick testing or a CGM, I’d be real interested in looking at the dose/response curve after your typical meal. If pricking, one every 30 minutes post-meal until you fall back to baseline oughta do it. So 4 or 5 sticks.
I know that idea sounds pretty off-putting at first, but after a bit of practice / experience finger sticks are no big deal. IME worst case they feel about like a static shock from a doorknob and best case they feel like nothing. The average is biased heavily towards the “nothing” side.
Good luck. I agree w your attitude that this might be a sign of a problem or might not. But better to run some more experiments than to say “Ehh, who cares? More Pizza! More beer!!”