A1C represents the long-term glycation of hemoglobin due to blood sugar exposure. Even if you could measure it at home, it wouldn’t change fast enough for rapid tracking to be meaningful. You need to wait for red blood cells to be replaced (hence the 3 month cadence) before expecting any change in A1C.
> A1C represents the long-term glycation of hemoglobin due to blood sugar exposure.
You're not measuring HbA1C in real-time; you're measuring the blood sugar in real-time.
HbA1C is a lagging indicator, used because it's a convenient and non-invasive diagnostic and a summary statistic. It's not the way you measure the short-term or medium-term effectiveness of interventions.
Ah I misread your comment — thought you were suggesting measuring A1C at home, which wouldn’t get you anything. Re-reading, you definitely meant measure blood glucose itself.
I do wonder if A1C remains a useful metric though, as perhaps it better captures the actual damage done by consistently high blood glucose. Would be interesting to see if there is research showing that CGM area under the curve is a better (or worse) predictor of clinical outcomes than A1C.
> I do wonder if A1C remains a useful metric though, as perhaps it better captures the actual damage done by consistently high blood glucose.
Both metrics have their own use. Continuous glucose monitoring is better for measuring the short-term impact of interventions, but it's also more invasive (albeit less so than it used to be) and more expensive. HbA1C is still measured for diabetic patients who have continuous glucose monitoring.
One downside of A1C is that the baseline values actually vary, and it's known to be either downward biased or a particularly lagging indicator for certain groups that are predisposed to Type 2 diabetes (e.g. South Asians and people of African descent).
