I’m not skilled at knowing my BG; I mostly depend on the CGM. That said, if I see a white glowing ring around my central vision, this reliably indicates that I’m between 60 and 62. And at that level I walk more deliberately, as if I have the fatigue of walking 20 miles. Tingling lips suggest that I’m in the mid 50s, as does increased ringing in the ears. In the upper 40s I start to sweat mildly. If I wake up in the low 40s I have a strange buzzing sensation: not a sound but some sort of sensation of vibration at maybe 15Hz. And in the mid or low 40s my tastebuds are no longer able to detect sweet: glucose tabs get a metallic taste with no hint of sweetness. (So licking a glucose tab is a way to test if I am severely low.) My wife sometimes checks me for lows with math questions. Below 75 it becomes difficult so solve problems like “What is the square root of 700?” She’s not looking for a numerical answer, just a reasoning process like “20 squared is 400, so its more than 20; 30 squared is 900 so it’s closer to that; so the square root of 700 should be around 26 or 27.” In the 60s I have difficulty with problems that require borrowing, like “What’s 43 minus 17?” For high BG, I tend to get acid-reflux kind of sensations around 170.