Fasting with diabetes - my HOWTO guide for those on insulin

So, yesterday was one of the 2 25 hour fasts (no food, no liquid) in the Jewish calendar, and I decided to give fasting a shot. There’s a website for observant Jews with diabetes that gives some suggestions (, but I figured, since the question has been raised here before, that I’d put how I survived the fast out there.

IMPORTANT NOTE FOR THOSE ATTEMPTING THE JEWISH FAST DAYS: If your blood sugar drops too low, you are REQUIRED by halacha (Jewish ritual law) to break the fast. My understanding is that this is also true for Moslems, e.g. during Ramadan, but I do not pretend to have any expertise in Islamic ritual law.

Caveat: I take 1 shot of Lantus at night. If you split your basal, you probably want to leave your PM dose alone and reduce your AM dose. If you take only an AM dose, then you’re on your own :-).

What I did was this:

  1. Before the fast, I had about a gallon of fluid over a few hours and a pretty hefty dinner. I ended up with a 2hr post-prandial of 85 and a bedtime of 82.

  2. I didn’t have a snack for the 82, because I know that on my normal 10u of Lantus, I have a dawn effect of about 30-40 points.

  3. I took 6u of Lantus instead of 10u, knowing that I’d need to correct in the AM.

  4. In the AM, I was around 145 when I officially dragged my carcass out of bed. I took 3u of Humalog, which dropped me down to 117 2 hours later (I have spectacular insulin resistance in the AM. In the afternoon, 2u can drop me 100 points in 2 hours).

  5. I tested the heck out of myself. Around 6PM, I dropped to 75, (which prompted more frequent testing and a tube of glucose right at hand) but by 7PM, I was trending up a bit, and when the fast finished at 8:56, I was at 91. I pretty much stayed in the 75-95 range the whole day.

  6. After the fast, I ate like a pig :slight_smile: Took normal Lantus dose, and have had a really good blood sugar day.

If I were only doing a day fast, I’d probably leave the Lantus or only chop off a unit or 2. (For a day fast, I usually wake up and have breakfast before the fast starts and then go back to sleep.)

For pumpers, that website I gave has recommendations on basal reduction. Look in the article on Tishrei - they have Yom Kippur instructions. If you can read the Yiddish, more power to you :slight_smile:

I wouldn’t change my basals at all, but I am very confident in my basal settings. In fact, I’d look on the whole event as an opportunity to do a 25 hour basal test. Basically it’s a test to determine whether your basal doses keep your sugars more-or-less flat without food consumption. That is the job of our basal insulins.

I do understand that sticking to the fast is the prime objective here. Dropping basals to ensure you don’t go low is an admirable and acceptable sacrifice IMO. But yes, keep a syringe handy for corrections.

I’m curious how your sugars behaved after you finally ate, not so much the next day. I know I’d experience a large liver dump. This happens whenever I fast for basal testing.

When I grow up, I want to be as intune to my diabetic self as you are. Good job.

I went to sleep the night of the fast around 130, having had pizza, etc.

The 2 days after the fast, I’ve been having just about textbook perfect sugars. Minimal dawn effect, post-prandials under 130, random tests during the day 100 or less, and I’ve needed significantly less Humalog as well. I seem to have reawakened my honeymoon somehow.

My understanding is that your insulin requirements decline as you get deeper into a fast and that’s why you cut your basal dose for MDI or your basal rate for pumping, but I admittedly have zero pumping experience.

Dov, on a pump, I’m of the understanding (as Dave said) that you generally shouldn’t need to reduce your basal.

The times you might need to is if you are normally very active, but on Yom Kippur, one assumes you will have your tush on a seat most of the day.

My pump (and I assume others) have different basal programs. I might, for example, use my weekend basal program, if my life changes a lot on a weekend. So having said that you shouldn’t need to change your basal, your basal needs are sometimes not the same every day of the week or every week of the year.

If you’ve done your homework, then you already know what kind of day Yom Kippur will be for you and how that relates to your normal activity, and you’ll already have a basal program in place for that… maybe with minor tweaks.

Maybe ‘deeper’ into a fast also means reduced activity. You certainly wouldn’t want to be be doing marathons on a fast.

Many people on insulin (and indeed those on Type 2 pills) are advised to consult a doctor and rabbi, and I’m also of the understanding that some are forbidden to fast.

Dov, did you consult your doc and rabbi to see if you were allowed or forbidden to fast, or is that a decision you made because you knew you could get through it ok?

Dov, I appreciate your discussion. It raises an important question for all of us, not only fasters for religious concerns.
Is/Are everyone’s basal dose(s) keeping everyone free from lows? A basal dose should keep us in our target zone.
The reason I ask myself this is

  1. if I end up in surgery, I want to be sure an anesthesiologist will not run into lows. I want him able to be assured that I have my basal keeping me in my target zone - anytime. Sometime I might not have a chance to tell him beyond what is on a piece of paper in my purse. In a car accident, for example.
  2. I do not want my basal putting me in the low zone and then I give a meal bolus on top of it. I want my meal injection to put me back in my target zone, and I don’t want my meal injection to put me back into a low zone.