On fasting, for myself, I see it as an important treatment tool that T2 diabetics have at their disposal. Which is apparently how it was used before metformin and so on came in on the scene.
I experience hunger too keenly to be a happy Intermittent Fast-er, so I personally go for the periodic short-ish (4-5 days) and sharp Dr Fuhrman's water fast as my glycogen depleting/liver and pancreas rebooting etc fasting method of choice. My reasoning is - keep the misery in a manageable block of time! And not try to live a normal (unhungry) life at that time.
Reference: Fasting and eating for health: A medical doctor’s program for conquering disease by Joel Fuhrman MD
I have done it twice, once successfully, in terms of what I wanted to gain from it - which was as much psychological as physical (get myself used to dealing with hunger in prep for a low calorie diet period), the physical benefits being obvious for we diabetics, in terms of temporarily halting, and depleting the stream of blood glucose we deal with, for a restive period of time, depleting glycogen stores in the liver etc. I was pleased with both of those aspects of it.
The second time was at the end of the low calorie diet, and I was scared shitless (I choose that word carefully!), by the low BG levels, and the - shitlessness. So I stopped it on day 2 or 3 I can't remember now. But I ought not to have been scared by the low BG levels, I know that now. My inexperience showing. (I was under medical supervision, but in the country I currently live in it can take 1-2 months to get an appointment and no avenue for outside of an appointment communication with either your doctor or the diabetes nurse. Yeah - makes 'medical supervision' a bit of a joke - but 'oh well'.) And re the unfortunate constipation - I wasn't drinking enough liquid obviously. (Always really really important, as all fasting lit points out.) Next time I will probably take a fibre supplement, just to be on the safe side. But yes, I fully intend there to be a next time.
I don't know the time frame that is best for me, in my T2D treatment, as I am really just winging it! But I feel that some time soon is called for. (7-9 months since fast one and fast two.)