HbA1c: What's Optimal, What's My Data?

That youtuber, biohacker's A1C of 5.1 is very good.  Hes very low carb.  

I'm low carb, zero carbs from vegetables, only meat. My source of carbs is from lower carb chocolate (the 4th or 5th essential food group). We drink wine via the low carb distributor, dry farms wine, dryfarmswines.com, which have only .6g / l . Yet my A1C is 5.6. So his 5.1 is VERY good.

Paroting from the Boca low carb conf;   4.8 is a goal,  the more ketones you are burning the longer lived the red blood cells and higher the A1C (measured) but your effective A1C would be much lower then your tested number.   I can't give any physiological or data backing up my reporting from a prior conf that red blood cells live longer on keto...   The A1C test measures the percent of red blood cells that show signs of glycation thus if cells live longer your percent glycated would go up (vs norming).

Regardless;  IMHO an A1C in the low 5's is a goal and is difficult due to food temptations or ones diet of carby vegies or fruit OR if your glucose state allows red blood cells to live longer (data to be found).   A1C is the ultimate tattletale of your glucose ave over the last 3 mo.  Morning fasting glucose is almost useless.  A CGM is much more useful, but the A1C is a good report card thats cheap.   Every other mo A1C blood test + wearing a CGM is the top strategy to stay in ketosis, keep insulin lowest.

Best to all, curt