Fasting Safely With Type 1 Diabetes: The Complete Guide for Yom Kippur 5787

BS"D

A person with diabetes is only allowed to try the fast when the conditions are met: you understand the risks, you have prepared for them, and you are going to follow the guidelines. That is what this guide is.

This guide replaces everything we have sent out in previous years. Every instruction you need is here. Where the reasoning behind an instruction runs longer than a guide can carry, there is a link to the post that makes the case in full.

If you have been following our posts these past weeks, some of this will be familiar. Read it anyway, top to bottom. It is organized here in a way a run of posts cannot be, and the gaps between them are filled in.

There is also a one-page settings card, which is what to keep in front of you on the day: download it here.

Much of what follows we have been saying for over twenty years. What has changed is the pumps, and with them some of the instructions. If you have our guide from a previous year, throw it away.

In this guide:

• Who Cannot Fast
• The Tightrope
• Confidence, and the Year Behind You
• The Target: 120
• Why Exercise Mode Is Not Safer
• The First Night
• Pump by Pump
• For People Not on a Pump
• The Warning Signs of DKA
• Ketone Testing
• Treating a Low, and Treating a High
• Erev Yom Kippur
• Finishing and Breaking the Fast

1. Who Cannot Fast

Before anything practical, here is who should not be doing a full fast. Nobody on this list is simply exempt. A person who may not do a full fast eats and drinks shiurim, and that is their obligation for the day.

• Your doctor does not allow it. A Torah-observant doctor, who understands what fasting means to you and will not simply tell you not to.
• You are new to diabetes. This is not an exact calendar, but the first six months is really too early, and our Rav does not allow fasting then. Between six months and a year it depends on you. If you are already comfortable, and you know your own body, your own diabetes and your own system, you can fast. If you are not there yet, wait for next year.
• Your settings are not yet settled. If you recently moved from injections to a pump, or from an older pump to a sophisticated one, the question is not how long it has been. It is whether the settings are finalized and whether you know how the system behaves. If they are not, the fast is not the day to find out.
• You are expecting. Pregnancy raises the risk of DKA, and a full fast is not an option.
• You are nursing. Here the concern is dehydration. A fast day is dehydrating in any case, and nursing takes more fluid out of you on top of it.
• A thin young teenager. Low body weight raises the risk of DKA, and a thin young teenager should not attempt a full fast. This is not new and it is not negotiable.
• You had a severe low in the days before the fast. A bad low empties the liver's reserve of stored glucose, and that reserve is what carries you through a fast day. It has not been refilled by the next morning.
• Your blood sugars are completely out of control.
• You are not ready to understand the risks and follow exact instructions.
• You are not fully committed, before the fast begins, to eat or drink the moment a low happens. Our Rav made this a condition of fasting at all. A person who would hesitate – wait and see, let me watch what the pump does – is not allowed to begin fasting.

One item that is not on this list: taking Jardiance or another SGLT2 inhibitor does not bar you from fasting. It does mean a conversation with the doctor who prescribed it, and the conversation is about when to stop the medication before the fast. Some guidance calls for 3 to 4 days, so if this is you, call today.

On the thin young teenager, a word to parents. This one needs strong coaching, because a child who is told they may not fast hears it as being left out. Explain that eating less than a shiur is still, halachically, fasting. And tell them that a year or two or three down the road, bez"H, they will be able to do a full fast.

2. The Tightrope

Because we live with pumps and sensors, we think of insulin as a way to control blood sugar: more insulin lowers the number, less insulin raises it. But insulin is far more than that. Insulin is life itself. It is what keeps the body from going into diabetic ketoacidosis.

Too much insulin causes a low and forces us to break the fast. Too little leaves us open to DKA. And it is not only high blood sugar that causes DKA, it is a lack of insulin – a person can have normal, or even low, blood sugars and still be in DKA. In medical terms that is euglycemic DKA, and it is known and documented.

So which of the two risks do we avoid? A low can usually be treated quickly and safely by somebody who prepared for it, and you can see it coming. DKA is life-threatening, hard to reverse, and there is no reliable way to know you are crossing into it until it has begun. Both practically and halachically the matter is clear: it is forbidden to fast in a way that risks DKA, even when avoiding it means eating or drinking to treat a low.

Which leads to a sentence people find hard, and it is the foundation of everything below. If the only way you can get through the day without a low is to reduce a lot of insulin, the fast is over. Not be careful. Over.

The full case, with the physiology behind it, is in Fasting on Yom Kippur – Part 3.

3. Confidence, and the Year Behind You

Confidence in your pump system means one specific thing. You can keep your target low enough that you are getting enough insulin, and you can hold it there without being afraid of going low. Both at once. A person who is only safe from lows because the target is high does not have confidence, and neither does a person who gets plenty of insulin but keeps dropping too low.

People write and ask me to skip the explanation and just say what to do. I understand the request, but the explanation is the condition. The only way you are allowed to fast is if you understand diabetes, you understand your body, and you understand your device. If you read this guide and could not explain to somebody else why a higher target is the dangerous side, then fasting is not for you this year.

That is not a punishment, and it is not forever. You will be allowed to fast when you learn what this is and how to control it.

And look at what a person without that confidence is left with. The only way to keep yourself away from a low is to raise the target. Raising the target means less insulin, and less insulin is the DKA risk. So the one tool available is a tool you are not allowed to pick up.

Where that confidence comes from differs by pump. On Tandem the algorithm works from your own settings: your programmed basal is the foundation it adjusts around, so settings that are off are delivered all day long, and a settings review is what earns you confidence there. The twiist also runs off your settings, but it reads your sensitivity from the last half hour and predicts six hours ahead, so it absorbs a great deal that is wrong. On the Medtronic 780G and the iLet the pump builds its own picture from your total insulin, and your programmed basal is not in the loop at all. There the confidence comes from the year behind you, and from nothing else.

A question we were asked: should I switch to a different pump for Yom Kippur? No. You would be walking into the fast on a system with no track record at all – new settings, new algorithm, new habits – on the one day you cannot afford to learn anything.

One more thing belongs here, whatever pump you are on. If your numbers are being held up by a basal that is quietly covering food, then your system is not holding you, and a fast day is exactly where that shows. Section 7 explains how to recognize it. And if you cannot tell whether it is you, and there is nobody you can ask before the fast, then this is not your year to fast.

4. The Target: 120

It is hard to give one exact number that fits everybody, but two things can be said without hesitation. A target of 140 to 160 is too high, full stop, because it takes off too much insulin. And 120 works for most people. It sits comfortably above a low and it is low enough to keep the insulin flowing.

On most systems 120 is the ordinary setting rather than something you have to reach for:

• Omnipod 5 – set the target to 120.
• Medtronic 780G – 120. This is the lowest the pump will take, and the algorithm is built to hold you steady there.
• iLet – the middle of its three settings, "Usual," which is about 120.
• twiist – a correction range of about 115 to 125 for the fast.
• Tandem Control-IQ – Tandem is the exception, and it gets its own section below.

A target higher than 130 reduces insulin delivery too much and raises the risk of DKA. That is the line for the day of the fast. The first night is the one exception, and it is section 6.

Why the higher target is the dangerous side, worked through in full: Fasting on Yom Kippur – Part 4.

5. Why Exercise Mode Is Not Safer

Put the whole day together. No boluses for twenty-five hours, because there is no food. The basal shrinking hour by hour as the liver's stores run down. The pump cutting insulin further on its own every time the number drifts. Now raise the target to 140 or 160, and the pump takes off more insulin still. Every one of those is a reduction, and they do not replace each other. They stack.

Exercise mode has no place on any system during the fast, and on Tandem it is worse than on the others. On Omnipod, Medtronic and the iLet the feature raises the aim: the pump is still working to hold you at a number, only a higher one. Tandem's Exercise Mode also moves the point where the pump starts taking insulin away, from 112 up to 140, and it puts nothing back until it predicts 160. On a fast day, when the numbers are drifting down anyway, that is a pump cutting insulin at a number where every other system would be leaving you alone.

That does not make the feature safe on any other pump. Exercise mode, activity mode, a high temp target, whatever your pump calls it – on every system it means less insulin, on the one day when less insulin is the danger.

Your doctor may have told you to use exercise mode

I am not a doctor. But on this one instruction, on this one day of the year, we are in disagreement, and I have no choice but to say so.

I have spoken to people after a fast who ended up in DKA, or close to it – large ketones, throwing up, and needing intervention. When I asked, they had been in exercise mode all day.

Nobody handed me a lab report, and a person can vomit on a fast day for other reasons. But large ketones and vomiting on a fast is a real doubt, and a real doubt is what we are obligated to act on.

The reason is euglycemic DKA. The blood sugar looks fine while the insulin underneath it is too low, which is exactly what a raised target produces, so nothing on the screen warns anybody until it has already begun.

If you have been told to put your pump in exercise mode for the fast, raise it with the person who told you, and ask about euglycemic DKA specifically.

"I used exercise mode last year and I was fine"

You got through it. That is not the same as having been safe. A low announces itself, so a year without one tells you something. DKA does not announce itself, which is the whole problem with it, so getting through a day on exercise mode tells you only that you did not cross the line that day. It does not tell you how close you came, and it does not tell you that this year will run the same way.

We are not permitted to take that risk, and last year going well does not turn it into a permitted one.

6. The First Night

The first night is the exception. After the last meal there is plenty of insulin on board, and the first hours are where most people who break a fast break it. A higher target there is not cutting insulin you need. It is easing off insulin you already have.

A range of 140 to 150 for those first hours is what we have always allowed.

Set it for six hours from your last bolus, and let the pump end it by itself. The usual figure for how long a bolus works is three or four hours, but it can still be doing something at six, and that stretch is exactly what the higher target is for.

• Omnipod 5 – the Activity Feature takes a duration.
• Medtronic 780G – temp target takes a duration. Press it after the last meal and let it hand back to your 120.
• iLet – the Higher target, set as temporary with an automatic end. It reaches about 130 rather than 140 to 150, which is fine – use what the pump gives you.
• Tandem – Exercise Mode raises the target to 140–160 and takes a timer, so set it for six hours and it ends itself. This is the one time it belongs on. A temp rate in Control-IQ+ also runs on a timer if you would rather lower the basal than raise the target.
• twiist – the time-of-day slot ends itself. On the workout preset there is no timer, so you are the one who ends it: at six hours if you are still awake, or at four hours before you go to bed if your numbers are steady.

On the twiist, keep your phone with you. Without it you cannot see your numbers, or what the system is doing for you, and the first hours are exactly when you need to.

Nobody has to touch a pump at midnight, and nobody should wake up in the morning still in a mode that is cutting insulin at 140.

One limit worth knowing: none of these tools reaches the insulin already on board from the last meal, so they are real but modest. The bigger lever is the meal itself, which is section 12.

From last year: Lows on the First Night of Yom Kippur: Three Reasons and How to Prepare.

7. Pump by Pump

Omnipod 5

Set your target to 120 for the fast. The Activity Feature raises the target to 150, so it is not for the day of the fast. It has a place on the first night only – see section 6.

Medtronic 780G

The Medtronic has two different things that both get called a target, and confusing them is easy.

The first is your target – the setting in the pump, 100, 110 or 120. That is where SmartGuard aims all day, every day. It is a permanent setting, and for the fast it should be 120.

The second is temp target – a button that overrides your target with 150 for a set number of hours and then hands control back. It exists for exercise, and everything this guide says about exercise mode applies to it. For the whole fast, no. For the first hours after the last meal, yes.

And the thing that bothers Medtronic users most, that you cannot micromanage the basal, is not the loss it feels like. On a fast day the basal is coming down whether you touch it or not, and the pump is already doing the reducing, every five minutes.

iLet

The iLet takes almost no input from the user, but it does let you choose among three settings: Lower, about 110; Usual, about 120; and Higher, about 130. Usual is the setting for the fast. The Higher target can be set as temporary with an automatic end, which is what makes it useful for the first night.

twiist

The twiist lets you set the correction range yourself, and a fasting range of about 115 to 125 is where it belongs. There are two ways to give the fast its own range.

The workout preset takes whatever range you give it, so your year-round range never has to be touched, and it is the simpler of the two. It runs for one hour, two hours, or until you turn it off, so for the first night you set it to run until you turn it off, and you are the one who ends it. If you are awake at six hours from your last bolus, end it then. If you are going to sleep when you get home from Kol Nidrei, do not leave it running overnight: at four hours, if your numbers are steady, put it back before you go to bed.

The other way is to set the correction range by time of day. Give the first night its own slot with the higher range and the day its own slot with 115 to 125, and the pump ends each one by itself while you sleep. That is the old special Yom Kippur profile in new clothes, and it carries the old profile's one chore: remember to take the slots out after Yom Kippur.

Tandem Control-IQ

Tandem is different from the other pumps in that there is no target you can set. Control-IQ has its own numbers built into each mode, and choosing your target on Tandem means choosing which mode to be in.

Two settings look like the answer and are not. The Target BG in your profile, usually 110, feeds only the bolus calculator; Control-IQ ignores it, and on a fast day with no boluses it does nothing at all. A temp rate lowers the basal the pump is working from, but it does not move the numbers the mode aims at.

Control-IQ+ did not change any of this. What it added is that a temp rate can run while Control-IQ is on, with a duration, which is why it is the Tandem tool for the first night.

The three modes are an insulin ladder. Sleep gives the most, Regular the middle, Exercise the least.

• Sleep Mode pushes basal insulin in as soon as it predicts you above 120, where Regular Mode waits until 160. On the DKA side that makes it the mode that gives the most insulin, and it is what we advised in earlier years. The feedback that came back was too many lows.
• Regular Mode has a second tool, an automatic correction bolus delivered when the pump predicts a rise past 180. On a fast that can be a problem, because a bolus can work stronger than usual when you are dehydrated, and a bolus cannot be taken back, where a basal change is gradual.
• Exercise Mode is off the table – see section 5.

On the insulin-cutting side, Sleep and Regular behave the same – both leave you alone until 112 – so Sleep Mode's risk is the low, not DKA. The middle way, and what we recommend for most people, is Regular Mode with the correction factor softened.

If your own year says something else, and you run Sleep Mode around the clock and it holds you, and you fasted on it last year and it went well, then it is yours to use. Both halves matter: Sleep Mode holding you on an ordinary night is not the same as holding you through a day with no food. We moved off Sleep Mode because of the feedback, not because the mode is wrong – too many people were going low on it. If you were not one of them, you already have your answer.

Softening the correction factor. If your pump gives one unit for every 40 points, change it to one unit for every 60. That is less insulin per correction, not more – at 1:60, those same 40 points give two thirds of a unit. If your number is different, raise it by about the same proportion: 1:50 becomes 1:75, 1:80 becomes 1:120.

First: is your basal really yours?

Before the instructions, one question, and it matters most to teenagers.

A basal can end up covering food. A bolus gets missed, the numbers run high, the basal gets raised to bring them down, and nobody goes back afterward. If your carb counting is only approximate, your basal may be doing half the job. And here is the sign that is easiest to recognize: if you eat late on a Shabbos or Sunday and go low waiting for breakfast, or for the Shabbos meal, your basal is covering part of that meal.

Yom Kippur is that Shabbos morning, for twenty-five hours.

This is a settings problem before it is a fast-day problem, and it is working against you every day of the year. Fixing it is two changes, not one. The carb counting has to get accurate, so the boluses cover the meals. And the basal has to come down, because once the boluses are doing their job the basal is no longer needed to cover food.

Doing only the second is dangerous: lower the basal while the carb counting is still not precise, and nothing is covering the meals. Doing only the first sends you low, because now you are getting the bolus and the basal that was standing in for it.

That is work for your diabetes team, and the call belongs weeks before a fast. Make it after yom tov if you cannot make it now. In the meantime, here is what to do for the fast itself.

Path one – your basal is right

• Regular Mode for the fast.
• Soften the correction factor – one unit for every 40 points becomes one unit for every 60.
• First night only: a temp rate on a timer, set to end six hours after your last bolus (section 6).
• Exercise Mode: not at all.

Path two – your basal is covering food

Everything in path one, and in addition, pull the basal back for the day. A temp rate of about minus 20%, running through the whole fast, is a reasonable place to start. It is a suggestion and not a prescription, because the right amount is personal – but you do not have to get it exactly right. Control-IQ keeps working on top of a temp rate: it goes on modulating the basal and still delivers automatic corrections, so it is there to catch you either way. Set it, and then leave it alone and let the algorithm work.

(If your pump does not let you set a temp rate while Control-IQ is running, you are on the older software. Ask your doctor's office to start the Control-IQ+ update for you, and in the meantime do the same thing by building a second profile named Fasting, with the basal pulled back and the correction factor softened, and switch to it at the start of the fast.)

Every pump, side by side, with readers' own experience of each: the Feedback Forum on the fast on every pump.

8. For People Not on a Pump

Long-acting insulin does not offer the same flexibility as a pump, but a fast can still be done well.

• One long-acting shot at night: cut the dose by a third. If you take 24 units, take 16. Consider adding 10% back to the Motzai Yom Kippur dose.
• One long-acting shot in the morning: leave the Erev Yom Kippur dose as usual, and cut the Yom Kippur morning dose in half. If you take 24 units, take 12. You may need some correction shots during the day, and more insulin than usual when breaking the fast.
• A split dose, morning and night: cut the night dose by 20% and the morning dose by 40%. If you take 20 units at night, take 16; if you take 20 in the morning, take 12. Consider adding 20% back to the Motzai Yom Kippur dose.

Everything else in this guide applies to you exactly as it does to somebody on a pump.

9. The Warning Signs of DKA

Nausea is the first sign, and the most common one. At any hint of nausea during a fast, suspect DKA.

Shortness of breath, or heavy, deep breathing, is the second. Some people feel no nausea at all and begin breathing this way in the early stages.

A headache is not on this list. A headache is what fasting feels like, and it is very unlikely to be DKA on its own. That is the difference between a real doubt and any possibility a person can imagine.

What to do, the moment either one appears:

• If you have a ketone meter, check right away.
• If you cannot check, act anyway. Break the fast – eat and drink regularly, not shiurim.

The point of eating is to be able to take insulin. Insulin is the only thing that stops DKA. Sipping slowly on a sweet drink is the most effective way in, because it gives you carbs gently and lets you take insulin without triggering vomiting.

This is why acting early matters so much. Once nausea turns into vomiting you can no longer eat, which means you can no longer safely take insulin, and the DKA worsens. No food, no insulin, worse DKA. When the nausea is still mild, a person can usually manage to sip a sweet drink slowly and keep it down.

Water is not the answer to ketones, and this is worth understanding rather than just being told. Drinking does flush some of what is already in you out through the kidneys, so it is not useless. But it does nothing to stop your body making more. Only insulin puts a cap on the production, and while the production is running, flushing is emptying a bucket that is still filling.

Fluids do help in another way. A hydrated body distributes insulin better, so the insulin you take works better.

I have witnessed these scenarios over the years, including trips to the emergency room at the end of Yom Kippur with good blood sugars. Please do not take this lightly.

10. Ketone Testing

Ketones by themselves are not DKA. It is perfectly natural for a body to produce ketones during a fast – a person without diabetes does too. So a ketone reading does not tell you that the line into DKA is being crossed. As long as there is enough insulin in the bloodstream, ketones alone will not progress into DKA.

Which means that checking every two hours from the morning onward is of limited value, and if everybody did it, many would break their fast without any real danger. The safeguard is not the ketone reading. It is making sure enough insulin is always going in.

Check when there is a reason to: at any sign of nausea or shortness of breath, and it is reasonable to check if your numbers have been running high. And once you have eaten and taken extra insulin, check again.

• 0.6 to 1.5 on a blood ketone meter – moderate. Continue eating and drinking shiurim for the rest of the day.
• 1.6 and above – large. Stop fasting immediately. Begin eating and drinking regularly for the rest of the day.

From last year: Ketone Testing During the Yom Kippur Fast.

It has to be a blood ketone meter. Urine strips and breath analyzers are not the tool for this, and urine output is diminished while fasting anyway. In America the KETO-MOJO GK+ kit is around $50 and is still what I would buy. Outside America, buy whatever you can get: every blood ketone meter measures the same thing on the same scale, and a 1.5 is a 1.5 on every brand.

Two things to do before yom tov. Check the expiration date on the strips, because a meter bought during one scare and left in a drawer usually has nothing usable in it. And open it and do one test now, while you feel fine. A meter still sealed in its box on Yom Kippur afternoon, being opened by somebody who already feels sick, is not a meter. It is a box.

Which meter, and what to do if you cannot find one: A Ketone Meter Before Yom Kippur – Four Notes.

11. Treating a Low, and Treating a High

A low

Either one of these is a low: a number below 70, or your usual symptoms with no number at all. Either one on its own, and you do not need both. Sensor readings are less reliable when you are dehydrated, and the sensor can show 70 when you are 50, so a screen that looks fine is not an answer to a symptom you are feeling. Treat the symptoms, not only the numbers.

There are two situations here, and mixing them up is where people get stuck. If the blood sugar is heading down and the low has not landed yet, you can still eat pachos m'kshiur, less than the shiur, and if it works you have treated it and you are still fasting. Once the low is there, there are no shiurim. You take what you need at once.

Which is why it is worth knowing what less than the shiur looks like in a candy you are actually holding. Our Rav crushed Winkies into a measuring cup: four full rolls are still less than the shiur. Four full rolls, not four tablets – a roll is fifteen tablets, about 6 grams of carb. (Winkies are also sold as Fizzers, and as Smarties in the American stores.)

How much a shiur is, and how often you may take one: Eating on Yom Kippur: How Much, and How Often.

Take the candy together with something to drink. On a fast day the mouth is dry and everything is moving slower, and a candy sitting in a dry mouth is not doing much for you. The drink is not instead of the candy, it is carrying it. And eating and drinking are two separate measures, so two rolls of Winkies and 40 milliliters of juice are each under their own shiur rather than one larger amount.

A low can happen more than once, and each one gets treated as it comes. There is nothing to count to. The low arrives, you treat it.

And on how a low is treated on Yom Kippur, our Rav has ruled clearly. A person with a low blood sugar does not use a workaround to bring it up. No intravenous glucose, no glucagon, no suppositories. Through the mouth, and nothing else. This is halacha.

The whole of it, including the tefillah and the mitzvah a person has who eats: Fasting on Yom Kippur – Part 6: When the Low Has Already Happened.

A high

If your blood sugar rises above 180, correct with a very small amount of insulin, or let the pump take care of it. Wait at least two hours before correcting again, to give the insulin a chance to work. Insulin and dehydration are a tricky combination: the insulin may work stronger, and it may also work slower.

12. Erev Yom Kippur

Your sensor and your set

The pump sees two things: the insulin it believes it delivered, and the sensor readings. Both should be settled and proven before Kol Nidrei.

A sensor is at its least accuracy on its first day, so a sensor started close to Kol Nidrei gives you unreliable numbers through the opening stretch of the fast – which is exactly the stretch where most people who break a fast break it. Aim for a sensor that is at least twenty-four hours old when the fast begins, and check the expiry date so that it is still running the morning after.

An infusion set can fail quietly. It can pass enough insulin to cover basal while being unable to deliver the larger amounts a meal needs, and nothing tells you until the meal. So put a fresh set in early on Erev Yom Kippur, and let the day's meals test it before Kol Nidrei. A set put in at the end of the day is tested for the first time by the seudah hamafsekes, which is the worst possible moment to find out.

The mikvah is where this collides. There is a specific hakpada on Erev Yom Kippur about a chatzitzah even on a small part of the body, and it pushes people to take everything off before they go. Doing that forces a fresh sensor and a fresh set into the hours before a twenty-five hour fast, which is precisely what should not happen.

Our Rav has ruled that a sensor is not a chatzitzah for men, and for us there is no real choice: we go to the mikvah on Erev Yom Kippur with the devices on. What I do myself, and this is my own suggestion and not a psak I received, is to take one clean tevilah in the last days before Yom Kippur with nothing on the body, having in mind that this tevilah is for Yom Kippur.

What to take to shul

Take what you might need to shul before yom tov. Put it somewhere you will find it quickly, and tell one other person where it is.

• Your own fast sugar – juice or winkies, enough for more than one low. Do not plan on finding the children's candy.
• A spare infusion set and cartridge, and a spare sensor.
• Your ketone meter, with strips that are in date.
• A glucose meter and strips, for the times the sensor cannot be trusted.
• Insulin, if you are not on a pump.

The meals

Measure the carbs in the meals carefully. Do not overeat. Try under-bolusing a little for the last meal, to avoid going low at night, and if you go high, correct very carefully so you do not send yourself into a low.

People who need to treat a low on Yom Kippur usually need to do it during the first night, and those lows are largely avoidable with careful carb counting and dosing at the last meal. Lowering the carbs at that meal is the single biggest lever you have over the first night.

13. Finishing and Breaking the Fast

Return to your normal settings about an hour before the fast ends, unless your blood sugar is really on the low side.

At the zman, even before Maariv and Havdala, start drinking water. Hydration matters here, because insulin is distributed better through a hydrated body.

Some people do better by adding insulin at the meal. What you can do depends on the pump.

• Tandem – a temporary basal of 150% of your usual, for a couple of hours from the zman. Control-IQ keeps working on top of it.
• twiist – set the pre-meal range.
• Medtronic 780G – there is no temp basal in SmartGuard, so the lever is the target. Put it back to normal, or lower. If you usually run 120, set 100 for the evening.
• Omnipod 5 – the same. Back to your normal target, or down to 100.
• iLet – back to Usual, or the Lower setting, which is about 110.

The other way, and it works on every pump, is a stronger carb ratio for the meal – more insulin per carb than you normally take. Think about what the word breakfast means. It is break-fast, and most people already need more insulin per carb at breakfast than later in the day, after a fast of ten or twelve hours. This is a fast of twenty-five. The same ratio you use for breakfast is the starting point, and you may need more than that.

Do not do both hard at once. Pick one, see how the night goes, and note it for next year.

Wait a half hour between your first bolus and eating, or watch your sensor to see the insulin start working. Do not eat too many carbs, and especially not all at once, or the numbers will go very high. Rabbi Weissmandl ruled that a person who cannot control their after-fast numbers is not allowed to fast.

· · ·

When people fast, what they see in front of their eyes is the blood sugar. Will I go low. That is the question that fills the day.

There is a different question that belongs in front of it. Am I doing enough to stay away from DKA? If the answer is yes – if your target is where it should be, your system holds you there, and you know what you would do the moment it did not – then you can try to fast. If the answer is no, you cannot. Not this year.

It is advisable to review your own plan with your doctor before the fast.

Everything we publish on fasting, and on living with diabetes the rest of the year, is at The FWD Daily & Weekly Loop. Membership is free.

Wishing you a gmar chasima tova, and an easy, meaningful fast.

Rabbi Hirsch Meisels
Friends With Diabetes International – ריעים מתוקים
Phone 845-352-7532 · Text 845-470-5510 · Fax 845-573-9276
Web FriendsWithDiabetes.org

P.S. We would appreciate hearing how your fast worked out. This is the last email we will send about fasting this year.