I have been doing a little experiment on myself. First, I transitioned over the course of a week or two to a significantly lower carb, lower insulin, higher fat diet; stayed on it for a two or three months and blood glucose levels levelled out. Re-introduced higher levels of carb., plus (initially) the sorts of levels of insulin my body would have needed before my LCHF experiment. Disastrous response, and a need for extra regulatory doses of insulin to bring BG down for any significant carb intake. I shall be going back to lower carb, lower insulin, better me from now on, transitioning again as I know the body has to get used to knowing how to bring about any kind of dynamic stasis. (57.5 years in with Type 1and still learning!) My sister reminded me recently that a low carb, high fat diet was what I was initially brought up on in the late fifties and early sixties - I had a lot of cheese as a young child - and possibly why early diet has protected me from too many side-effects, health-wise.
I am told that my insulin intake is low for a T1: 5u Lantus (down from 10, before LCHF) and bolus dose of 4,4,4 Novorapid, as intake requires, given later metabolising of protein to BG, (In my recent upping of CHO intake I was back way up at 8: 8, 8, 8, plus some regulatory doses.) Up and down does not suit my system at all.
Anyway, sorry to bore, but sometimes we have to try for ourselves what we think may be soundly based and workable, or best for us, though I would add that getting a doctor's advice before radically changing diet and insulin regime is highly advisable.
I see, I drive, my kidneys work (though the blood supply to my legs is down to 65% - but I smoked for years...). I feel better knowing my BG will be under 13 but not much below 4, and when I was stable on LCHF it was between 4 and 8 - 9 all the time it was marvellous, so I'm going back there. I am already on statins - seems to be standard - so I'll ask for a blood test in about three months, I guess, and weigh up the odds. My latest diabetic clinic appointment gave me no opportunity to discuss all this, my experience, my reasons etc. so with the help of this forum I am ploughing my own furrow.