Bloods came back "prediabetic" and I run 40k a week and eat like a saint. How is my HbA1c in the grey zone and what am I actually meant to do while I wait for the recheck?

Right, I'm annoyed and a bit rattled so bear with me. Annual bloods, the sensible risk-based panel I've settled on, and the one line I never gave a second thought to comes back flagged: HbA1c 43, with the word "prediabetes" next to it. The nurse's note says repeat in three months.

I run 40k a week. I'm not overweight. I eat, if anything, boringly well. My whole identity is "the fit one". And apparently my three-month blood sugar average has quietly put me in a grey zone I associate with the exact opposite of how I live. My first reaction was that the lab made a mistake, my second was to google, which as we all know here is a mistake, and my third was to eat a banana in defiance and then panic that I'd made it worse.

So: how is this even possible for someone who does everything the leaflets say? Is 43 actually a big deal or is it the diabetes version of a value that's technically flagged but basically nothing? And what am I supposed to DO in the three months between now and the recheck, besides quietly lose my mind? I'd rather not repeat my thyroid-nodule mistake of spending six weeks in a hole over a number that turns out to be fine.

The "I do everything right, how dare my bloods" energy is extremely relatable. Different number, same slap in the face. For what it's worth, "repeat in three months" is the calmest instruction on the whole menu, they'd move a lot faster than that if they thought it was urgent. The waiting is the tax, not the diagnosis.

My brother-in-law got parked in that same grey zone for two years, ate roughly the same, and it never budged into anything. Doctor called it a nudge, not a verdict. Genetics do a lot of the driving apparently, whatever the leaflets imply about it all being down to what you had for breakfast.

Gregor, I hate that you're in the waiting-hole version, I know exactly how it feels and I'm sorry. One thing that helped me last time: I wrote down the actual instruction (repeat in three months, nothing before then) and stuck it on the fridge, so that when the 1am version of my brain wanted to reinterpret it as something scarier, I had the boring real sentence in front of me. Doesn't fix it, takes the edge off.

Gregor, direct answer first: an HbA1c of 43 is at the very bottom edge of the prediabetes zone, it is a "keep an eye on this" signal and not a diagnosis of anything, and a single reading there is exactly why the sensible instruction is a repeat rather than an alarm. Now the detail, because the detail is genuinely reassuring here.

HbA1c is measured in mmol/mol in a lot of the world, and the common bands run roughly: below 42 normal, 42 to 47 the prediabetes or "at risk" grey zone, and 48 or above in the diabetes range where they'd want to confirm on a second test. (In the percentage units some labs use, those cut points are about 5.7 and 6.5 percent.) You're at 43, which is one unit over the line. That is not "nearly diabetic", it's "just inside a wide cautionary band that's designed to catch people early", and the whole point of the band is that it's a prompt to recheck, not to panic. A number that close to a threshold is also well within the range where normal test-to-test variation can nudge you either side of the line, which is one reason they repeat it.

On your central bafflement: fitness and a good diet lower your risk a lot, but they don't override everything. HbA1c reflects a three-month average blood glucose, and it's pushed around by genetics and family history, by age, and by things that have nothing to do with lifestyle at all. That last part matters here: HbA1c can read falsely high or falsely low in people with certain anaemias, iron deficiency, recent blood loss, some inherited haemoglobin variants, or after a big change in red-cell turnover, and endurance runners are not immune to a few of those. So a borderline value in a very fit person is genuinely worth confirming before anyone reads a story into it.

What to do in the three months: keep living exactly as you do, don't crash-diet or carb-purge in a panic (it can actually distort the picture and it won't meaningfully move a three-month average anyway), and go to the recheck. That's it. If it helps to understand what the number is and isn't measuring, the site's blood glucose and diabetes screening guide covers HbA1c specifically, and understanding your blood test results is the wider version of why one flagged line near a cut point is a recheck and not a sentence. The exception I'll flag honestly: if you develop actual symptoms in the meantime, unusual thirst, weeing far more than normal, unexplained weight loss, don't wait the three months, ring your clinician, because that changes the picture. Absent that, this is a watch-and-repeat, and most people in your exact spot recheck into the normal range or sit stable for years.

Recheck done early because the clinic had a slot, and closing the loop: came back 41, back under the line, filed as "normal, keep doing what you're doing". So my banana of defiance is exonerated.

The useful lesson, and the reason I'm posting the ending rather than just quietly moving on: I did NOT spend these three weeks in the thyroid-nodule hole this time, and the difference was understanding that 43 was one unit into a wide early-warning band built to be twitchy on purpose, not a near-miss with diabetes. Knowing WHY the number sat where it did is what let me put it down. Thanks all, and Annika, the fridge sentence genuinely worked.