Can someone explain interstitial glucose readings versus finger prick readings, and their relation to GMI / A1C?
I'm getting really confused trying to keep track of this.
My understanding is that GMI and A1C are not the same, and for example, a GMI of 6% is equivalent to an A1C of 5.5%. And my understanding is that this is because your CGM is reading interstitial fluid, while a finger prick or blood draw is reading your blood.
However, when trying to look up whether interstitial fluid naturally reads higher than a blood draw, the answer I seem to be finding is "no". In other words, if your CGM is reading a pretty steady number all night, then your blood draw or finger prick test would show roughly the same number.
But if that's the case, why is GMI so different from A1C? I think I'm missing a key piece of information that ties this all together, and there's also a very good chance that something I've posted above is just flat-out incorrect. Can someone help me make better sense of this?