Take Very Good
Care of YourselvesDeuteronomy 4:15



 You need to use your brains not your emotions!

Fasting can become a luxury when combined with almost any medical issue.  Diabetes is certainly one of those cases and this article will focus primarily on diabetes due to the many details involved.  However, we stress here and in all our publications, when it comes to fasting with s medical condition, one must first review all aspects with your medical team and then bring those facts to a Rabbi that is competent on the specific medical facts.

 Advances in diabetic technological device and knowledge now allow many people with diabetes the luxury of fasting almost problem-free.  We will attempt to explain the various parameters, so that you can personalize this information with your medical team and Rabbi.

 Most Jews find it very difficult to fathom eating on most fast days, especially on Yom Kippur and the 9th of Av. It is, therefore, quite understandable that many find it distressing when they are told that they must eat.

We have reviewed these issues with a number of Rabbis but we bring here the view of Rabbi Yitzchak Zilberstien Shlita. He is the head Rabbi in Mayanei Hayeshua Hospital Kollel in Benei Barak Israel. 

One with diabetes, even in good control and even if a doctor allows it, may only fast on Yom Kippur and not on any other fast day. Rabbi Zilberstien Shlita goes on to tell us that for someone that is told by a doctor that he/she is not allowed to fast, it is important to try and convince them to heed the words of our Rabbis.  The Chazon Ish Grand Rabbi of Benei Barak in the past generation and Rabbi Akiva Eiger Ztzl of blessed memory used to go to the hospitals to convince people that they must eat.  Rabbi Zilberstien Shlit goes on to tell us that for those that have to eat, if they study the Laws of The fast it is accepted as though they have fasted completely.

It is advisable to try and NOT overload on carbs before the fast.

 Protein is easier to digest and will sustain you longer.

 We caution this is not an instruction sheet for fasting. It is only a guideline that one can use when working out a correct The fast regimen with their Rabbi and Doctor.

 Do not make decisions in Halacha Jewish law without speaking to a Rabbi whose first question will be What did your doctor tell you to do, or changes in regimen without consulting with medical professionals.

 For those using long- acting insulin Ultra-lente, Lantus:

Long acting insulin supplies the blood with a steady stream of insulin throughout a twenty-four hour period. Without this supply, blood glucose levels would automatically rise in those whose pancreas has stopped making its own insulin.  Therefore, those who take long acting insulin should never cut out insulin completely, even during a fast.

 Experience has proven that often the basal amount should be lowered somewhat before the fast.  Dr Lois Jovanovic of the Sansum Medical Center in Santa Barbara and member of our medical board of advisors, recommends the following calculations:

It is probably best to take no more than 0.3 times the weight in kilograms of Lantus before bed. If BG is slightly elevated during the day one can always take some short acting NovoLog, Humalog insulin. Dr. Jovanovic recommends 1-2 units every 2-3 hours that blood glucose is over 200. Discuss with your Doctor exactly how much insulin to use to lower elevated BGs on The fast.

 Always make sure that there is someone in your synagogue and at home that knows that you have diabetes and are fasting, and that knows what to do in case of an emergency!

  For those using intermediate insulin Lente, NPH, Insulatard:

Intermediate insulin covers basal needs by supplying insulin over a twelve hour period. Intermediate insulin doses are often times coordinated to cover specific snacks or mealtimes, along with supplying a steady basal rate.  If that is the case for you, make sure to consult with your doctor about adjustments for a day without food. 

Dr. Jovanovic recommends:

It is best not to depend on the previous doses of morning insulin. Recommended doses of morning intermediate insulin NPH/Insultard should be reduced to the basal need or 0.1 times the weight in kilograms. Likewise the bedtime dose of NPH/Insultard should be 0.1 times the weight in kilograms.

 For those using pre-mixed insulins: 

We once again quote Dr. Lois Jovanovic:

Pre-mixed insulins are dangerous to take for a fast!  They have a fixed dose of short acting insulin and should not be used if no food is eaten.

 For those using short-acting insulin - Novo Rapid [NovoLog, Humalog

Short acting insulin is absorbed within fifteen minutes after injection into the body, and pretty much clears the system within three to four hours.  It is used to directly target meals and snacks, and allows for great flexibility in scheduling.  Its fast acting properties also make it ideal for lowering high blood sugars.  However, should be used cautiously when not eating.

 High Blood Sugars:

On the occasion of an elevated blood sugar, one would cautiously take a small amount of short acting insulin novo-rapid during the fast. Keep in mind that when fasting, many factors that would normally cause insulin resistance, such as food and overeating, are not present. Insulin can therefore work more efficiently on a fast day.  It is advisable to err on the side of caution and remember that smaller doses of any insulin are always easier to control.  As Dr. Richard Bernstein the author of The Diabetes Solution notes,

 Big insulin-big mistakes.  Little insulin-little mistakes.

 And again Dr. Jovanovic recommends 1-2 units every 3-4 hours that blood glucose is over 200. Check with your doctor these are only general guidelines.

 Low Blood Sugars:

 According to the Jewish Law, there are proscribed amounts of food and drink, called shiurim, as well as a nine-minute time interval observed between eating/drinking sessions for those who must eat on Yom Kippur. When experiencing a low blood sugar, stay calm and remember that treatment should start to work within 5-10 minutes.  Three-four rolls of aspirin candies Winkies are within the allowed amount according to Jewish law, and are very effective as an immediate aid.  If drinking is necessary, one should try not to exceed more than one ounce at a time.  According to Jewish law, one should wait five minutes between drinking sessions.

Obviously, in an urgent situation, treating a low within the perimeters of shiurim may not be possible.

Always make sure that there is someone in the synagogue and at home that knows what to do in case of an emergency!

 Note:   Rabbi Zalman Nechemia Goldberg Shlita, of Jerusalem cautions that if fasting will cause one to check their blood sugars more often than normal, fasting may be problematic according to Jewish Law. It has been reiterated by many of the Rabbis that we have discussed fasting with that one can fast on Yom Kippur providing that one will not test more often than on a regular Shabbat Sabbath day.  Our experience has shown that most often when fasting and not dealing with food one usually ends up testing far less then on the Sabbath.

 For mild Hypoglycemia Below 70-80 mg/dl. The following are less than the shiur.

15 gr. of fast acting glucose e.g. 6 Glucose tablets, 2-3 rolls of small aspirin like sour candies etc...

1 oz. 30 gr. small whisky cup of frozen juice concentrate. This is best to open before the fast and keep defrosted in the refrigerator. Equivalent to 1/2 cup juice mixed with water.

For blood sugar below 50-60 mg/dl:

This can be very serious and should be treated with double the amount. Most often this should be followed with a snack, Again this possibility should be discussed with ones Doctor and Rabbi.

For severe Hypoglycemia Below 40 mg/dl:

If the person is conscious but not eating rub either, honey, glucose gel, or packaged cake icing on the gums, upper palate, and inside cheek. Once the individual is more responsive this should be followed by standard treatment and food.

If the individual is not conscious then Glucagon must be administered! And once they regain consciousness they should NOT continue fasting!

Those with T2DM previously referred to as adult uninsulin dependent that are on an insulin regimen, would, need to follow the guidelines above.

The same applies for those that are on Pump therapy.  In general, one parameter of judging the success of pump therapy is good control with a great decline in low blood sugars and for many even when one does experience a low blood sugar due to the small doses, they are far less severe and need much less treatment to bring one to a normal blood sugar. This is providing that basals are correct

For those that are on oral medication alone, or no medication, they would need to discuss with their Rabbi/Doctor exactly how to deal with their personal situation.

There are many oral medications that tend to lower Blood Sugars, and many that build up in the system over time and not taking the medication may result in poor control the next day or even a few days after the fast.  It is, therefore, vital to check with your medical team


In order to help avoid dehydration which is often one of the primary reasons for headaches, nausea etc when fasting,

It is recommended to drink at least 8-15 glasses of water throughout the day before the fast.

It is a Mitzvah righteous act according to Torah law to eat on the day before Yom Kippur. In order to avoid overeating on carbs, having sugar free gum, and/or an occasional sugar free candy remember that they are not carb free, so keep an eye on how many you have in addition to your regular eating, can help you fulfill the Mitzvah.

For the last two meals eaten prior to the beginning of the fast, eat and cover with medication as you normally would. These two meals are usually in close proximity of each other. When testing before the second meal if BGs are elevated remember the unused insulin rules.  There still may be insulin in the system from the previous dose.

The same applies when testing right before the beginning of the fast. A chart of insulin activities follows.. Be careful about piggy backing insulin. This is often a cause for low BGs later on. For those that do not cover meals with short acting insulin, remember to explain to your doctor that there are 2 meals where more than the normal amount of carbohydrates may be eaten. Remember overeating calls for additional insulin. Extra insulin tends to be more difficult to control and less predictable. It can, also, make you hungry.

There are those that recommend loading up on carbs before a fast. This may be good advice for those that do not have diabetes or insulin resistance. Again, keep in mind that this will call for more insulin and/or cause elevated BGs. It is better to stick to normal and doable amounts of food. Remember that high BGs will cause more thirst and discomfort during the fast. Proteins tend to satiate for longer periods of time then carbs.


After the fast most people have a tendency to overeat and this can be quite taxing-our recommendation is to start slow-Drink firstyou are not really half as hungry as you think.  When not fed for an extended period of time fat cells shrink they do not die and they soak up food real fast sort of like a dehydrated sponge put in water and no matter what you eat your blood sugars will soar-drinking lots of water and start with proteins first.  This can help slow the absorption of glucose once you start eating carbohydrates.

 More articles about fasting:

The Sigal guide to fasting:


 Ending the fast in good control:



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