Rational fasting can help lower BG. By breaking habitual eating patterns, retraining our sense of fullness/satiation, increasing/resetting hypo awareness we are more likely to eat what we need instead of all that we could.
Delayed eating is more effective than extended fasting for quickly determining a rough basal profile.
The thing is that “basal rate” for someone who needs insulin infusion is partly a function of intestine contents and we are directed to maintain a reasonably regular schedule of eating. I determined my basal profile by fasting for different 12 hour intervals, my night profile assumes I ate an average meal at ~6pm, Not a liquid diet for 24 hours preceding an empty bowel.
A “basal rate” is a metric like A1C. It doesn’t measure basal need, but average demand. It’s not what happens in real time, it’s an average over an interval under average conditions.
I think of basal rate like idle fuel consumption in a car. Idle consumption varies with what has been happening. Idle is faster before a car warns up, become more efficient and sloiws as the car enters closed loop operation controlled by the exhaust monitors. It increases when loads like AC , headlights,and radio are turned on. It varies between cars with different engine displacements and idle speeds.
No one can determine a sleeping “basal rate” for fasting in any individual with diabetes without empirically measuring it. Chronic stress level, sleep quality and profile, body mass, fat reserves, activity, ambient air temperature and humidity liver and kidney health all vary. They all effect BG dynamically because BG is affected directly and indirectly by multiple hormone levels.
Interstitial CGMs aren’t perfect, but give more insight into BG variation and insulin needs than BGMs.
The latest gen of integrated infusion systems was what convinced me to finally switch from MDI. I can see variations in my basal need as Control IQs Sleep “activity” mode adjusts my insulin delivery dynamically every night based on BG. My BG (and BP, pulse and resp.) all rise as I awaken, before I get up, because of a noise outside, for a bathroom break, as I am having a nightmare. (All this is between 1 and 4AM, before my well-documented dawn rise.)
During waking hours, two days with identical meals and virtually identical activity can have total “basal” that varies by 10% because of psychological or situational stress.