What’s the highest A1c you’ve ever seen? If it were very high, such as 23.9 at diagnosis, is that likely inaccurate? I wasn’t all that high blood sugar-wise (around 1100 mg/dl [61.1 mmol/L], but I want to know if the A1c were some kind of record.

You are incorrect. A blood sugar of 1100 mg/dl [61.1 mmol/L] is extremely high and very dangerous. The highest A1c I’ve ever seen was 25%, so you are pretty close to “my record” but not quite the worst.

SB
Additional comments from Dr. Linda DiMeglio:

The usual assay for hemoglobin A1c, using the DCA 2000 machine, does not go over 14% – so numbers greater than 14 are usually not done with the same sort of technique as the A1c assessment that you’re used to seeing in clinic. The other techniques have slightly different reference ranges, but I’ve never seen any as high as what you were reported. Since the A1c is an integrated estimate of the blood sugars over the last three months, albeit more heavily weighted to the last two to four weeks – (see HbA1c Measurement), it only very minimally reflects any single number or any single day’s glucoses. Sometimes we measure total glycosylated hemoglobin (A1c is only one type of glycosylated hemoglobin), or hemoglobinA1, but these are not as useful clinically as an A1c (and again I’ve not seen these assays run as high as what you report).

One other value sometimes reported other than A1c is fructosamine. This is another way to indirectly measure an integrated blood sugar but reflects values over the last two to three weeks rather than three months. These values usually range from 200 to 600.

LAD