My first meeting with a diabetes educator, four days after I was diagnosed with type 1 diabetes, was on the 12th of Elul in the Jewish calendar. Yom Kippur was less than a month away and very much on my mind. Could I fast with diabetes?
In reality, I already had. The fast of the 9th of Av, one month earlier, had been the roughest fast I had ever endured. My body, already in a state of starvation, had not been well able to withstand the difficulties of a fast, and I was unable to stand up at the conclusion of the day.
But a month later, on insulin, I had more energy, more ideas about what was going on with my body, and more questions.
My CDE said that yes, I could fast with diabetes. Or at least, I could give it a try. That first year, that "try" was an uncertain guess. The way that I and my diabetes team decided it, I would eat once during the day, and I would eat an amount that allowed me to be technically considered fasting. The lantus dose was reduced slightly the morning before the fast, and halved for the day of the fast. I ate a very small compressed amount of raisins early in the day, tested blood sugar and ketones, and finished feeling very successful.
By the next fast day, I was adjusting my own dosages and had a much better idea of what I was doing. I had also learned a few things. In the last six to seven years, I've learned a lot about fasting with diabetes both from attempting fasts on roughly forty holidays, as well as fasting for a number of medical procedures.
Here are some things I have learned:
1. Consider what other health issues you have going into the fast. If you have another health issue in addition to diabetes that will make it hard for you to fast or to recover from fasting, you may want to skip it. One year when I fasted for Tisha B'Av despite some problems with stomach acid, the stomach ache that resulted lasted for close to a month afterwards.
2. Two of the Jewish fast days come in convenient pairs, with a minor fast day one week (for Tzom Gedalia and Yom Kippur) or three weeks (for shiva assar b'tamuz and tisha b'av) before a more major and important fast day. The minor fast day makes for a really good trial run, and having a trial run is very helpful for getting the basal right for fasting. Anytime you really want to be sure you're going to be able to fast, and don't know how much to lower insulin doses, it's a good idea to see how long you go without eating without going low on your regular dose or with a modest decrease so that you have a better idea of how much to lower the dose for the big day.
3. Although you may get away with taking no insulin at all for a fast day if you are making a lot of your own insulin, with non-honeymooning, non-latent type 1 diabetes, that will send you into DKA. Also, simply running high (even upper 200s) will dehydrate me badly enough to make fasting difficult or even medically inadvisable.
I have never made the mistake of taking no Lantus for a fast day, but I have made the mistake of taking too little insulin for the meal prior to the fast, and/or of not correcting highs for too long.
Although you should be less aggressive correcting highs on a fast day, it is still necessary to keep blood sugar below about 250.
4. The meal after the fast raises my blood sugar quickly and needs a breakfast ratio, not a supper ratio.
5. With a 25 hour fast, dehydration will develop. And the dehydration tends to cause insulin resistance and a rise in blood sugar towards the end of the day.
6. The basal insulin for the night after the fast has to be kept low; I have a tendency to drop very low that night if I take the usual Lantus dose.
7. Eating the large customary meal immediately before the fast does not work for me because if my injection for the meal is too much, I end up with a low right at the beginning of the fast, which is no good. And it's hard to get the dose just right. It is better to eat the big meal a few hours before the fast, allowing for time for adjustments. Drink water or another low carb beverage right before the fast.
8. In order to safely fast, a diabetic on insulin must be prepared to break the fast. I must check for lows, and I must be willing to eat a little bit if I go low. And if I go really high, and get ketones, I must be willing to eat and drink to get rid of them. But at the end of the day, if you have made it through the fast day having eaten just 8 grams of sugar in 25 hours, you will probably still feel like you made the day a fast day as it is supposed to be.
Do your best to decrease the odds that you will need to eat or drink, but if you have to eat, that doesn't mean that you have to eat so much that you entirely disregard the fast.
In addition to the religious value of fasting, this practice also came in handy for me for knowing how to deal with NPO times prior to surgery, endoscopy, and ultrasounds.
Much medical literature has been written about diabetics fasting Jewish fast days as well as Ramadan. Most doctors who have written about it agree that diabetes by itself is not a reason for a person to not fast, but many times fasts must be planned on with adjustments to medication and insulin dosages.
In general, persons on insulin will need their dosages lowered by at least 20% for basal insulin and possibly more. Depending on the oral medication, it may or may not be omitted. People with diet controlled diabetes do not need to make any adjustments or preparations to fast, except perhaps for not eating a huge meal right before the fast.
Two readable articles:
Managing Diabetes During the Fasting Month of Ramadan
http://www.e-mjm.org/2012/v67n3/Diabetes.pdf
Management of diabetes mellitus on Yom Kippur and other Jewish fast days
by Grajower MM is a worthwhile read if you have access to the full article.
http://www.ncbi.nlm.nih.gov/pubmed/18463037
Please if you have experience fasting with diabetes, reply with your experience. Thank you.