Fasting Question

Has anyone on this forum successfully fasted for a week at a time and what were you blood glucose related experiences if so? This would include no food, very limited amounts of food or the Prolon fast.

This would be a spiritual fast in my case as well as possible health benefits so no judgments please. I’d love to hear how others have fasted and how long they were able to while maintaining stable glucose control.

I used to fast for up to four days in a row during post-graduate study for no other reason than just to save time, since I otherwise had to buy and prepare all my own food. I felt all right for the first three days of the fast, but by the morning of the fourth day I was really tired walking up the hill between my apartment and the university.

For blood sugar control I omitted all meal blousing, since there were no meals, and I took only half my normal basal dose. Blood sugar results were fairly but not perfectly stable.

The concern for diabetics trying this is that many of them may have declining renal function and not be aware of it, and renal health is put under great stress by the person not metabolizing anything, so make sure your creatinine level is normal before embarking on a fast if you’re a member of this high-risk group.

Thanks for the informative tips, upon doing more research I’m going to be consuming small amounts of calories instead of completely cutting everything out during this time.

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HERE you can find more information:

Fasting with Type 1 diabetes:

Thanks for that @Mila but this article states the obvious, I appreciate the consideration though I really do! This article could be exceptionally helpful for those recently diagnosed.

What I’m wondering is if anyone has actually done a fast as a diabetic and what were your blood sugar results?

I understand it’s a touchy subject, if anyone’s been through it please feel welcome to PM me!

Sorry, I don’t have first hand experience in fasting for a week. I have only gone 3 days and that was due to a surgical procedure. And I had no problem due to basal rates being set correctly and the one time I started heading downward, I just suspended the pump for awhile. I would imagine if your basal rate is set correctly and you start your fast in a good blood sugar range, you should be good. I’m sure you’ve talked with your medical team about this. I know if I was doing something like this my team would help me make it happen if it was important for me and my well being, whether physical, mental or spiritual. Good luck!

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I am an insulin using T??.

Last year I did a 5-day fast, as part of my exploration of keto lifestyle and for the experience / to see how I would feel [I am moderator of a keto group which has lots of people who experiment with fasting, so I wanted to actually experience fasting myself].

During the fast I still took plenty of non-calorific liquids, and salt. I use Levemir and Humalog insulins. I maintained normal activities during the fast (ie. work, chores etc) but did not try exercise other than walking.

Day 1 morning I took my usual Levemir. Day 1 evening I cut Levemir by about 20%.
Day 2 morning I cut Levemir by 50%. Same for Day 2 Evening.
Day 3 to Day 5 I did not take any insulin. I continued to closely monitor blood sugars.

End of day 5 I had a light dinner. I took 50% of usual night time Levemir. Day 6, back to normal insulin dosing schedule.

Some people say that they have lower insulin requirements after a fast. I didn’t experience that. I went immediately back to my regular dosing.

I did not have any lows during the 5 days and I felt fine. Blood sugars were in the 70 to 90s range mostly. Note: I had been eating keto for months already at that point and am pretty sure I was well keto adapted.

If you decide to fast, monitor very closely (blood sugar, and I’d recommend blood pressure too - though I didn’t). Keep up the electrolytes and fluids. Be ready to correct any lows with glucose / dextrose. If you feel at all unwell or “strange” be prepared to stop the fast.

I believe that fasting has a place in spiritual and health paradigms. However, it should be done with good preparation and understanding, treated with great respect, and stopped if necessary. There is a difference between slight discomfort / hunger and being masochistic / pushing through at the expense of health. Given you are diabetic, the preparation and care is even more important. I am not dissuading you at all! Just urging knowledge, preparation and caution.


Great tips Sally.

Very well said, I wear a 670g so I’m assuming the pump will counter my needs which I’ll mention to my doctor. I think before using the 670 I would have been too paranoid to try anything of this nature but it’s great to read others success stories!

I was diagnosed 10 years ago with type l. Before that I’d fast at least once a year for 2-3 weeks, drinking only water. I loved to fast. I never felt better than when I fasted. It would put my RA into remission & give me boundless energy for weeks after. It also reset my diet. Less sugar, etc.,
This past April after reading about successful fasts & diabetes I started fasting. I kept it easy, only 1 week & only if my BG levels were good. They were. They were great, staying between 85-100. I stopped taking insulin as I didn’t need it. I drank lots of water, at least a liter a day. I started to feel bad on the 6th day. I felt worse on the 7th. I tried to slowly introduce food but started vomiting. I was in the ICU that night with a team of doctors trying to find a useable vein. I was diagnosed with DKA.
I’d only recommend fasting with the strict guidance of a doctor.

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Ooh! Scary!

Thanks for letting us know @CristineMcC, I’m glad you are ok now. Did you have any warning signs on that 6th day blood sugar wise? I know you mentioned you started to feel bad but did you have any highs to go along with that or did it hit you suddenly?

@Elyssia_Reedy - I do 48 hour fasts several times a month. I pump, and lower my basal about 30% (total basal dose ~12 Units Humalog). The only bolus I take is upon waking to take care of dawn effect.

Here’s a 24 hour trace


Thanks @Jim_in_Calgary.

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@Elyssia_Reedy -

I should add that while doing EF’s (extended fasts) it’s important to keep well hydrated and to supplement your electrolytes (Na and K). Many people sip bone broth.

Also, I do have a Freestyle Ketone meter and during longer fasts your ketones tend to increase over the normal ketosis range of 1.5-3.0.

My ketones have been as high as 6.9 after 48 hrs of fasting, but as long as you’re taking insulin, you won’t go into diabetic ketoacidosis. Insulin puts the brakes on DKA, which is why it’s essential that you maintain adequate basal levels.

DKA doesn’t occur until well after 10 (usually in excess of 20)

Good luck Elyssia!

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Thanks again @Jim_in_Calgary, very informative. I’m a huge fan of bone broth in general.


No @Elyssia_Reedy , no highs at all. My BS were gorgeous so I had no need for insulin. I guess that was my mistake, the no insulin. I also didn’t check my ketones.
@Jim_in_Calgary has a well thought out regimen that I wish I had had when I attempted post diabetes fasting.