3.5 Or 4.0? Guidelines?

I think it comes from the latest DAFNE info. Tagging @Mel dCP and @kev-w because I'm sure it was mentioned in T1 thread.

It was said DAFNE said 3.5 but I queried this last week at the clinic as I disagree, NICE guideline is 4 still, a 3.5 doesn't faze me but I'd still call it a hypo.

My view is that if we creep down to 3.5 being the new 4 then our hypo awareness will diminish faster than it needs to.

DAFNE does say 3.5 - I turn my pump down to 50% for half an hour when I get below 4.5 and off for the same if I’m below four. I function quite happily in the high threes though - but feel distinctly hypo below 3.5.

I think that we have to be aware of the error range of most glucose meters and also consider Libre and other GGM error ranges.
With say, a 15% error range, a reading of 4 mmol/l = a range of 3.4 to 4.6 mmol/l. i.e. in this error range both number definitions could apply.
And in another thread, the rule of having a BSL of 5 mmol/l or higher (? I forget in which countries is it 5 and higher or higher than 5 mmol/l) before setting out to drive a motor vehicle: 5 mmol/l with 15% range = 4.35 to 5.64 mmol/l. So a possible level of 4.35 mmol/l scrapes in as above the DAFNE guidelines and above the NICE guidlelines of 3.5 mmol/l.
The possibility of a degree of hypo unawareness is perhaps given some allowance in the 5 mmol/l "rule ", but that is a guess.
There are descriptions by diabetics (and I am one) of a BSL falling at a fast rate (? how defined) causing a person to experience hypo symptoms before reaching say, 5 mmol/l, whereas a more gradual fall in BSLs may not elicit hypo symptoms til levels lower than 3.5 mmol/l.
I hope that the above is clearer than mud !!!

4 is the roof for hypo where I live, in medical terms. But I won’t feel hypo at 3.5.

Wow, 3.5 mmol/l? If you're on insulin, that's too low in my opinion. If I were to adjust my hypo sensitivity down to that, I'd end up with way more hypos in the 2s. Would deffo increase the rate of more dangerous hypos.