I've been mulling it over for awhile, but now that I've got more experience with A1c numbers, I'm certain. The 5.1% A1c I had in May is wrong, wrong, wrong. Also, wrong.
How do I know? Well, back in March of last year, my fastings were very low normal and I had hypoglycemia every afternoon. My blood sugar was only elevated for two hours after eating and it was numbers like 140 or 160. My A1c at that time was 5.3%. My numbers steadily climbed and when I had another A1c done in January of this year, it was 5.8%. Then, my numbers went up even more, especially my fasting which went up by 10 points. My blood sugar stayed higher for much longer after meals. So, what was my A1c in May? 5.1%. So, you see, there's no way that can be correct. If anything, it should have been 6.1%. It was done at a different lab than the first two, but that's a really big variation. I'm not sure what happened at the lab of course, but if they mixed my sample up with someone else's they might suddenly find they're diagnosed diabetic!
I'm concerned because when a doctor sees that, they tend to assume the number is right (wrong), that I had great control on oral meds (wrong), that I shouldn't have gone on insulin (wrong). Unfortunately, I can't just stamp "wrong" right on the results. Hopefully I can convince the new endo, though.