ABSTRACT

Objective: To create guidelines for patients with dia-betes to fast safely on Yom Kippur and other Jewish fastdays, with the primary goal of avoiding hypoglycemia.

Methods: Almost 30 years of experience in endo-crinology and the pharmacokinetics and pharmacodynam-ics of current drug therapy were applied to develop theseguidelines and recommendations. A few illustrative casesare presented.

Results: Patients with either type 1 or type 2 diabeteswere able to fast safely when a treatment plan was proac-tively formulated before the fast day. An understanding ofwhich medications lower basal and which lower prandialblood glucose levels, as well as their duration of action, iscritical.

Conclusion: The overwhelming majority of patientswith type 1 or type 2 diabetes can, from the perspective ofblood glucose control, safely fast on Yom Kippur.Physician-patient discussion is important to prevent thepatient from relying only on personal judgment and poten-tially taking too much medication, with the resultantdevelopment of hypoglycemia. (Endocr Pract. 2008;14:305-311)

INTRODUCTION

Tailoring treatment for diabetes to an individualpatient’s lifestyle, rather than altering patient behavior toconform to a preconceived treatment plan, can result in a

more compliant patient and an improved physician-patientrelationship. One issue confronting Jewish patients withdiabetes is fasting on the holy day of Yom Kippur (JewishDay of Atonement). Many Jews observe 5 additional 1-day fasts throughout the year: the Ninth of Av, which lasts25 hours (beginning from sunset and lasting until about 1hour after sunset the following day) like Yom Kippur, and4 others lasting only from morning until night (from sun-rise to after sunset). These special days of fasting pro-scribe the intake of all food and liquids (including water)and, especially in the case of Yom Kippur, the holiest dayof the Jewish year, occupy an extremely important place inJewish religious observance.

When patients with diabetes ask their clinicianswhether they may fast, the clinicians must have knowl-edge of the scientific facts as well as sensitivity to the feel-ings of each patient, including both religious and healthconcerns. When physicians have carefully considered theindividual needs of each patient, rather than issuing a blan-ket statement that “patients with diabetes should not fast,”Jewish law would generally mandate that patients listen totheir physicians, especially those who are specialists.

As an Orthodox Jew and practicing endocrinologist, Itry to synthesize Jewish law with good medical practice.Each year, rabbis call me regarding people with type 1 ortype 2 diabetes who were told by their physicians (includ-ing endocrinologists) not to fast. My nearly 30-year expe-rience has been that, from the perspective of blood glucosealone, almost all patients not taking insulin can safely fast.The main exception is a patient with acute lack ofglycemic control in danger of dehydration. (Such a patientprobably needs insulin and is therefore not actually anexception.) The vast majority of patients taking insulin canalso safely fast, again with consideration of just bloodglucose control.

ILLUSTRATIVE CASES

Case 1A 55-year-old man had had type 2 diabetes for more

than 20 years. His most recent hemoglobin A1c (A1C)was 6.5% during treatment with a regimen of glipizide-ER(extended release), 10 mg twice a day; exenatide, 5 µgtwice a day; and metformin, 1,000 mg twice a day.

MANAGEMENT OF DIABETES MELLITUSON YOM KIPPUR AND OTHER JEWISH FAST DAYS

Martin M. Grajower, MD, FACP, FACE

Submitted for publication August 6, 2007Accepted for publication September 10, 2007From the Division of Endocrinology, Albert Einstein College of Medicine,Bronx, New York.Address correspondence and reprint requests to Dr. Martin M. Grajower,3736 Henry Hudson Parkway East, Bronx, NY 10463.© 2008 AACE.

ENDOCRINE PRACTICE Vol 14 No. 3 April 2008 305

Original Article

Abbreviation:A1C = hemoglobin A1c

Because he experienced hypoglycemia about every 6weeks (mainly after exercise), his endocrinologist advisedagainst fasting because of a concern about a potentialhypoglycemic episode. Independently, the patient attempt-ed fasting on the Ninth of Av. After taking his usualevening medicine, he ate dinner before the onset of the fastat sunset but skipped his usual 15-g carbohydrate bedtimesnack. At 6 AM the next morning, he experienced hypo-glycemia with a blood glucose level of 57 mg/dL.Therefore, he was referred to me for advice regarding fast-ing on Yom Kippur. I advised him to take exenatide andmetformin, but skip glipizide-ER, in the evening beforebeginning the fast. He took no medication on Yom Kippurday, nor did he check his blood glucose all day because hefelt well. At the termination of the fast, prior to eating, hisblood glucose level was 95 mg/dL.

Case 2A 72-year-old man had a 42-year history of type 1

diabetes. Although an observant Orthodox Jew, for 40years he had not fasted on Yom Kippur, explaining that heassumed he could not fast if taking insulin (although hedid not recall asking his physicians). Two years ago, whenhe became my patient, I inquired about adjusting hisinsulin so he could fast on Yom Kippur. He was elated atthe suggestion. His most recent A1C was 5.6% during useof a regimen of 10 U of insulin detemir (Levemir) at bed-time plus preprandial insulin lispro (Humalog) based oncarbohydrate counting. I recommended that he take hisusual insulin lispro dose before the pre-fast dinner but only5 U of insulin detemir at bedtime. He was to check hisblood glucose in the morning and then every 6 hours: if itdeclined below 60 mg/dL or he was symptomatic, he wasto take a sugar tablet; if it was 150 mg/dL or more, he wasto take 2 U of insulin lispro. On the morning of YomKippur, his blood glucose level was 286 mg/dL. He chosenot to take insulin then or 4 hours later, when it was 249mg/dL. At the end of the fast, his blood glucose was 193mg/dL. He took his usual insulin lispro dose before his“break-fast” meal. Two hours later, his glucose value was64 mg/dL.

Case 3An 84-year-old Holocaust survivor with a 15-year

history of type 2 diabetes, requiring insulin the past 5years, had always fasted on Yom Kippur. She was takingNovoLog Mix, 46 U before breakfast and 26 U before sup-per. Her last A1C was 6.4%, with home blood glucosedeterminations ranging from 110 to 150 mg/dL fasting and90 to 210 mg/dL postprandially. I advised her to take herusual NovoLog Mix dose before dinner prior to the fastbut only 10 U of NovoLog Mix on the morning of YomKippur. She was to check her blood glucose the first thingin the morning, then 2 hours after administration of herinsulin, and again 6 hours later. She was to take a sugar

tablet if her glucose value declined to less than 65 mg/dL.Her blood glucose levels on Yom Kippur were as follows:fasting, 151 mg/dL; 2 hours later, 96 mg/dL; 2 hours later,79 mg/dL; and before the meal that concluded her fast,130 mg/dL.

CONCEPTS

During the past decade, the treatment of diabetes hasbecome quite complex with the introduction of many newmedications. Accordingly, I believe that understandingcertain concepts would be helpful before outlining myapproach to the individual patient.

Most importantly, because each patient will be fastingas infrequently as once a year (Yom Kippur) and up to amaximum of 6 times, the main objective is to avoid hypo-glycemia, which would require the patient to terminate thefast.

An understanding of which medications lower basaland which lower prandial blood glucose levels, as well astheir duration of action, is critical. Medications with 24-hour duration will have an effect on the blood glucoselevel well into the fast day, whereas shorter acting medi-cines will exert their effect only on the pre-fast dinner.Similarly, when insulin doses are adjusted, the mainconsideration is the duration of action of the prescribedinsulin. Therefore, before daytime-only fasts (sunrise tosunset), because the patient eats normally the night beforethe fast, no need exists for adjustment of any short-actingprandial evening medications. One exception is if thepatient tends toward hypoglycemia during the night orearly morning; in such a case, I would reduce the doseof the medication (tablets or insulin) that is likely causingthis hypoglycemia. In contrast, because prior to a 25-hourfast the patient may eat dinner earlier than usual and willnot have a bedtime snack, the before-dinner medicationmay need adjustment to avoid nighttime hypoglycemia.

On the morning of the fast, patients with type 2 dia-betes rarely need medication. Even if the blood glucoselevel is high, the lack of ingestion of carbohydrates willimprove insulin sensitivity and lower the level of bloodglucose. In contrast, patients with type 1 diabetes do needsome basal but not short-acting insulin unless the bloodglucose values are high (arbitrarily, I use 250 mg/dL,keeping in mind the first concept).

A final consideration is the potential for each medica-tion to cause hypoglycemia, either alone or in combinationtherapy. Glucose-dependent medicines (biguanides, thia-zolidinediones, and exenatide) rarely cause hypoglycemia.

The other main therapeutic objective is to avoidhypotension, especially in older patients (see subsequentdiscussion of concurrent conditions). Everyone whorefrains from eating or drinking for 25 hours will becomedehydrated, and many otherwise healthy people will expe-rience a decrease in their blood pressure as a result.

306 Diabetes and Yom Kippur, Endocr Pract. 2008;14(No. 3)

GUIDELINES

As mentioned, the main objective is avoiding hypo-glycemia. Should hypoglycemia occur and the patientmust discontinue the fast, then the therapeutic plan did notaccomplish its purpose. On the other hand, should theblood glucose level increase during the course of one day,it will not create either a short-term or a long-term prob-lem (see pregnancy exception discussed subsequently). Ifanything, fasting itself has been shown to lower the bloodglucose level quite effectively (1). I continue all medicinesas usual the morning before the day of fasting. I do notgive any glucose-lowering medication (except insulin; seesubsequent information) on the day of the fast itself. Afterthe fast is over, I resume all medications at their usualtimes (that is, I do not have the patient take a tablet at nightthat normally would have been taken that morning).Therefore, the following guidelines refer to medicationtaken either at noon or later during the day preceding thefast and to insulin on the day of the fast itself (Table 1).

Antihyperglycemic agents that do not cause hypo-glycemia (biguanides and thiazolidinediones) can be takenas usual before the fast. Although dipeptidyl-peptidase-4inhibitors rarely cause hypoglycemia when used alone,they have been shown in clinical studies to result in hypo-glycemia in combination with other agents (including met-form and thiazolidinediones) (2,3). Because of their longhalf-life, they should not be taken later than the morningpreceding the onset of the fast. Other medicines with along half-life, such as sulfonylureas, should also not betaken later than the morning before the fast because theirprolonged action extending into the day of the fast couldcause hypoglycemia. Those medications with shorter half-lives, such as the short-acting insulin secretagogues(repaglinide and nateglinide), incretin mimetics (for exam-ple, exenatide), and amylin (Symlin), can be taken beforesupper on the day before the fast, inasmuch as this will bethe patient’s normal (or even increased) meal.

Insulin regimens always need to be adjusted begin-ning with the evening before the fast. In general, thedegree of glycemic control during the 1 to 2 weeks pre-ceding the fast day will influence the reduction in theinsulin dose. Bolus or short-acting insulin should be takenas usual before supper on the night before the fast. Ialways aim to use some basal insulin (intermediate- orlong-acting) during the fast (regardless if the basal insulinis taken at night or in the morning). I reduce the dose toone-third to one-half of the usual dose (based on the A1C)for a 25-hour fast. For a daytime-only fast, I reduce thedose to about 80% of the usual basal insulin dose. The bet-ter controlled the blood glucose levels are preceding thefast, the less basal insulin I recommend. I also reduce thedose of evening basal insulin if the patient normally has abedtime snack, inasmuch as the snack will not be taken thenight of Yom Kippur or the Ninth of Av. Bolus or short-

acting insulin is taken before eating the meal that con-cludes the fast; because many people will actually eat lessthan their usual amount at this meal, a slightly reduceddose may be indicated.

When in doubt about how much insulin to recom-mend, I err on the side of a lower dose. A high blood glu-cose level can be subsequently corrected without“breaking” the fast by having the patient take additionalsmall doses of short-acting insulin.

The combination insulins pose a slightly more diffi-cult adjustment. I generally reduce the dose to one-half toone-third of the usual dose, depending on the A1C.Ideally, the patients could take just the intermediate com-ponent of the combination insulin on the morning of thefast day. This approach, however, would entail buyingadditional insulin. Therefore, I tend to undertreat ratherthan overtreat these patients.

Patients with an insulin pump should not administer abolus of any insulin once the fast has begun (unless theblood glucose level exceeds 250 mg/dL). They shoulddecrease the basal rate by about 10% beginning in theearly morning (earlier if they normally take a bedtimesnack) and increase the frequency of blood glucose test-ing, especially the first time they fast using the pump.

DEALING WITH HYPOGLYCEMIA ON THEFAST DAY

The rules regarding eating and drinking on YomKippur (and, according to some rabbinic authorities, alsoon the Ninth of Av) (4) differ from the other Jewish fastdays. Accordingly, on Yom Kippur if patients have symp-toms of hypoglycemia, or document a blood glucose levelof less than 60 mg/dL, I advise them to take one of thecommercially available glucose tablets (rather than realfood or drink) and to retest the blood glucose in 30 to 60minutes. If patients have sustained hypoglycemia for a 1-to 2-hour period, the fast should be discontinued and foodeaten. My threshold for recommending that the fast be ter-minated is inversely proportional to the age and generalhealth of the patient. On the other Jewish fast days,because Jewish law views any oral intake as terminatingthe fast (4), I advise patients simply to break the fast ifsymptoms occur or the blood glucose level decreasesbelow 60 mg/dL.

CHECKING BLOOD GLUCOSE ON YOM KIPPUR

Yom Kippur differs from the other Jewish fast daysalso in that there is a prohibition against drawing bloodand using electrical devices (such as blood glucosemeters), unless necessary to preserve the sanctity of life.On the other Jewish fast days (including the Ninth of Avaccording to all rabbinic authorities), these prohibitions do

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308 Diabetes and Yom Kippur, Endocr Pract. 2008;14(No. 3)

Table 1Guidelines for Adjusting Antihyperglycemic Medications on 25-Hour Fast Days

(Yom Kippur and the Ninth of Av) That Last From Sundown Until After Sunset the Next Dayand Fasts That Last Only From Sunrise to Sunset on the Same Daya

Fast days Type 2 diabetes

and related Not taking Taking insulin Taking only

timing insulinb and oral agents insulin Type 1 diabetes

25-Hour fast days (Yom Kippur and Ninth of Av)Night before Do not take SU or Do not take SU or DPP-4 Take usual dose of short- Take usual dose of short-acting

DPP-4 inhibitors; inhibitors; take all other acting insulin before supper insulin before supper and one-

take all other medications before the and one-half to one-third the half to one-third the usual

medications normally last meal. Take usual usual evening dose of evening dose of intermediate-taken before supper dose of short-acting intermediate-acting or acting or basal insulin

insulin before supper and basal insulinone-half to one-third theusual evening dose ofintermediate-acting orbasal insulin

Day of fast Do not take any Do not take any Do not take any insulin Take one-half to one-third themedications medications unless blood glucose >250 dose of basal or intermediate-

including insulin mg/dL (then take some short- acting insulin in the morning.acting insulin analogue, and Take short-acting insulin

aim to lower only to 110-140 analogue only if blood glucose

mg/dL range) >250 mg/dL, and aim to lower

only to 110-140 mg/dL range

After the fast Resume all usual Resume all usual presupper Resume all usual presupper Resume all usual presupper andpresupper and and bedtime medications; and bedtime doses; adjust bedtime doses; adjust dose of

bedtime medications adjust dose of short-acting dose of short-acting insulin short-acting insulin if patient

insulin if patient will be if patient will be eating a will be eating a smaller suppereating a smaller supper smaller supper than usual than usualthan usual

Daytime-only fast daysNight before Do not take SU or Do not take SU or DPP-4 Take usual dose of short- Take usual dose of short-acting

DPP-4 inhibitors; inhibitors; take all other acting insulin. Reduce insulin. Reduce intermediate-

take all other medications before the intermediate- or long-acting or long-acting insulin to about

medications before last meal. Take usual insulin to about 80% of the 80% of the usual dose

the last meal dose of short-acting usual doseinsulin before supper;reduce dose ofintermediate-acting orbasal insulin by 20%

Day of fast Do not take any Do not take any medications Do not take any insulin Take one-half to one-third themedications including insulin. Take unless blood glucose >250 dose of intermediate-acting or

short-acting insulin mg/dL (then take some short- basal insulin, but no short-actinganalogue if blood glucose acting insulin analogue, and insulin unless blood glucose>250 mg/dL aim to lower only to 110-140 >250 mg/dL (except in patients

mg/dL range) on combination insulins; see text)

After the fast Resume all usual Resume all usual presupper Resume all usual presupper Resume all usual presupper andpresupper and and bedtime doses; adjust and bedtime doses; adjust bedtime doses; adjust dose of

bedtime medications dose of short-acting insulin dose of short-acting insulin short-acting insulin if patient

if patient will be eating a if patient will be eating a will be eating a smaller suppersmaller supper than usual smaller supper than usual than usual

aDPP-4 = dipeptidyl-peptidase-4; SU = sulfonylureas.bIncludes all orally administered agents and injectable incretin mimetics.

not apply, and the patient can, and therefore should, checkthe blood glucose freely. Therefore, the following guide-lines apply only to Yom Kippur.

Patients taking no antihyperglycemic medications arenot at risk for developing hypoglycemia and thereforeneed not check their blood glucose level during the entire25-hour fasting period. Patients taking antihyperglycemicagents (excluding insulin) who are known to have goodhypoglycemia awareness also need not check their bloodglucose level, unless they begin to have symptoms (someof the symptoms usually associated with hypoglycemia,such as tachycardia, could represent dehydration andhypotension, and the blood glucose should therefore bechecked). Elderly patients or those with documentedhypoglycemia unawareness should check their blood glu-cose level upon arising on the morning of the fast and thenevery 4 to 6 hours (sooner if glucose values decline below70 mg/dL), unless their only medications are those that donot cause hypoglycemia (as discussed previously).

I recommend that all patients taking insulin test theirblood glucose level upon arising on the morning of the fastand then every 4 to 6 hours (sooner if glucose values arebelow 70 mg/dL or the patient is symptomatic). I advisesupplemental rapid-acting insulin analogues (lispro,aspart, or glulisine; NOT regular insulin) for blood glu-cose levels greater than 250 mg/dL; I try to aim for a bloodglucose value in the range of 110 to 140 mg/dL.

WRITTEN RECOMMENDATIONS

On the basis of my experience, I recommend that thephysician provide the patient with written recommenda-tions that are made. In these written recommendations, Iinclude the following information: (1) changes in medica-tion before, during, and after the fast, (2) frequency ofblood glucose testing, and (3) “what if” planning for ter-minating the fast if the blood glucose level declines belowa specific value or the patient becomes symptomatic.Besides improving compliance by the patient, the writtenrecommendations become a part of the patient’s medicalrecords. I will generally follow-up with the patient at thenext office visit to learn how the patient fared on the fastday and note these comments for use the subsequent year.In most patients, I refer back to these written recommen-dations, which make it easier to advise the patient the fol-lowing year.

MANAGEMENT OF CONCURRENT CONDITIONS

A detailed discussion of how to manage concurrentconditions on a Jewish fast day in patients with diabetes isbeyond the intent of this article. A few short guidelines,based on my own experience and discussions with expertsin the specific specialties, seem appropriate.

In general, swallowing pills is not considered “break-ing” a fast (4). Liquids and chewable tablets, however, area problem. The main issue with most pills is, therefore, not

the taking of the medicine itself but the drinking of waterin order to swallow them. Although there may not alwaysbe consensus among Orthodox rabbis, a frequently quotedopinion allows drinking of aliquots of just under 30 mL ofwater at intervals of 9 minutes (4). Except where noted,the following recommendations all refer to taking medi-cines on the day of the fast itself, not before the fast begins.When in doubt about a specific medication, a usefulapproach is to ask yourself the following question: If thepatient went away for the weekend and forgot to take hismedications, and would not return home for 24 hours,would you recommend finding the nearest pharmacy andgetting an emergency supply (such as for corticosteroidsfor a patient with adrenal insufficiency or warfarin in apatient receiving anticoagulation therapy), or would youreassure the patient that a day’s dose could be missed(such as for statins or levothyroxine) or the dose could bedoubled on return home (such as for propylthiouracil ordiphenylhydantoin)? Once-a-day medications that neednot be taken fasting (for example, warfarin) can often betaken just before and then again just after the fast.

HypertensionBlood pressure medications are often the most chal-

lenging to adjust. On the one hand, skipping the medica-tion could result in excessive elevation of the bloodpressure. On the other hand, because the patient will not bedrinking or eating, there is the risk of dehydration andresultant hypotension, compounded if the patient is takingantihypertensive medication. I advise continuation of allthe usual medications before the fast. On the fast dayitself, I recommend skipping all antihypertensive medica-tions including diuretics, with the exception of β-adrener-gic blocking agents and clonidine, which I continue. If theblood pressure has been controlled to 120/70 mm Hg orless, I reduce the dose of the β-adrenergic blocking agentor clonidine. After the fast is over, I have patients takewhatever they would normally take at night. I do not“make up” for any missed doses from the morning or mid-day.

Cardiac ConditionsThe overwhelming majority of patients with stable

cardiac conditions tolerate fasting well. Recommendationsregarding cardiac medications need to be individualized tothe patient, on the basis of the extent of disease and thechronicity and stability of the conditions and associatedsymptoms. Morning medications for angina, arrhythmias,and congestive heart failure should, as a rule, be taken asusual. Evening oral medications may be taken during theevening before the beginning of the fast as well as after theconclusion of the fast on the following evening. Patientswho are deemed by their physician to have a condition sta-ble enough to fast should not take their diuretics on themorning of the fast. Medications that are taken for cardiacindications but also lower blood pressure (such as nitrates,angiotensin-converting enzyme inhibitors and angiotensin

Diabetes and Yom Kippur, Endocr Pract. 2008;14(No. 3) 309

receptor blockers, and calcium channel blockers) shouldbe evaluated on the basis of the patient’s symptom histo-ry, concurrent medications, and blood pressure readings,to avoid the development of hypotension while the patientis fasting.

Conditions Involving Corticosteroid TherapyIn order to avoid either the development of hypoten-

sion from adrenal insufficiency (compounded with thepotential hypotension from dehydration) or a flare-up ofthe underlying illness for which the corticosteroids wereprescribed, I do not change corticosteroid dosages.

PregnancyMany pregnant women have been advised by their

obstetricians not to fast on Yom Kippur for no reasonother than the fact that they are pregnant. There is no med-ical literature to support such a recommendation, yet anabundance of Judaic law supports fasting (5) (but only onYom Kippur and the Ninth of Av, not on the other 4Jewish fast days, when pregnant women need not fast) (5).I am aware of one medical study that assessed the safetyof a pregnant woman fasting on Yom Kippur and con-cluded that fasting can hasten the onset of labor and deliv-ery, but only in full-term fetuses (6). The authors found noincrease in premature births or fetal distress in pregnantwomen who fasted on Yom Kippur. Similarly, a study ofmore than 13,000 babies born to Muslim women who fast-ed during Ramadan found no effect on birth weight (7).

In pregnant women with diabetes, whether gestation-al or otherwise, the diabetes is controlled by either dietarymeans or insulin. For those with diet-controlled diabetes,there appears to be no difference during fasting than fornondiabetic pregnant women; fasting should, if anything,improve their diabetes control without an increased risk ofhypoglycemia. A pregnant woman receiving insulin is anexception to the general considerations already outlined;in such patients, physicians should attempt to avoid anydays of hyperglycemia because of the potential harmfuleffects on the fetus. Accordingly, I do not advise fastingfor a pregnant woman with either gestational or preexist-ing diabetes who is receiving insulin therapy.

DISCUSSION

Jewish law requires all female subjects 12 years andolder and all male subjects 13 years and older to fast dur-ing the year, especially on Yom Kippur. At the same time,Jewish law teaches that the sanctity of life overrides allthese fasts (4). If a person would in any way be risking hishealth by fasting, not only should he not fast, in fact hemust eat or drink (4).

When the physician, after considering the scientific aswell as religious issues, continues to believe that a specif-ic patient might be endangering himself by fasting, yetfinds that the patient feels strongly about proceeding withthe fast, the patient should be encouraged to discuss the

situation with a rabbi. In the case of Yom Kippur, and pos-sibly the Ninth of Av, a compromise position may be rec-ommended by the rabbi, whereby the patient drinks or eatsin small quantities and at specified intervals throughoutthe day rather than having 3 normal meals (4). On theother 4 fast days, once a person has to eat, there is no reli-gious reason to limit food intake.

My literature review revealed no published guidelinesfor managing diabetes on Jewish fast days. In 2005, rec-ommendations for management of fasting duringRamadan were published, based on a meeting of endocri-nologists and diabetologists from various countries (8).These recommendations are not applicable to fasting onYom Kippur for several reasons. First, the daily fast dur-ing Ramadan begins after breakfast, which is eaten beforesunrise, and lasts until sunset that evening, not 25 hours.Second, the fast days during Ramadan last an entire(lunar) month, whereas Jewish fast days occur one at atime, separated by anywhere from 1 week to severalmonths, and are limited to, at most, 6 during the entireyear. Third, Muslims maintain their usual activity levelwhile fasting during Ramadan, whereas on Yom Kippur,Jews rarely go to work and generally spend the majority ofthe day sedentary in synagogue.

Several studies have been conducted in which patientswith type 2 diabetes receiving no hypoglycemic medica-tions fasted for 3 to 10 days consecutively, during whichdrinking of noncaloric liquids was allowed (9). Thesestudies are relevant to the Jewish fast days in that theydemonstrated the safety of zero caloric intake in terms ofboth not developing hyperglycemia or other metabolicderangements as well as not developing hypoglycemia.The relevance of these studies is limited in that they didallow liquid intake. In addition, because the patients inthese studies had discontinued all hypoglycemic therapyfor at least 6 months, they did not demonstrate the safetyof taking hypoglycemic agents just before fasting.

In a study done on 15 patients with type 1 diabetestreated with bedtime insulin glargine and prandial rapid-acting insulin, the authors showed that if these patientsfasted for 18 hours after their usual dose of glargine, butdid not take any rapid-acting insulin, the average bloodglucose level declined by 32 mg/dL, and mild hypo-glycemic symptoms developed in only 2 patients (10).This study demonstrated the safety of fasting with use oflong-acting insulin. By reducing the dose of the long-act-ing insulin, which the authors of that study did not do, onecan substantially decrease the risk of hypoglycemia.

In my 30-year experience in practice, the most com-mon reason a patient with diabetes could not complete afast was not attributable to hypoglycemia or hyper-glycemia but because of dehydration and resultanthypotension. Therefore, one of my criteria for advising apatient with diabetes not to fast is my concern regardingdehydration. Examples of such scenarios would be apatient who has had considerably out-of-control bloodglucose levels during the 2 weeks before the upcoming

310 Diabetes and Yom Kippur, Endocr Pract. 2008;14(No. 3)

Diabetes and Yom Kippur, Endocr Pract. 2008;14(No. 3) 311

fast day, a patient who has recently had a cerebral hypox-ic event, or a patient with an underlying cardiac conditionwho tends to have low-normal blood pressure readings.Moreover, external factors must be considered. For exam-ple, a heat wave around the time of the fast day wouldincrease the possibility of dehydration, especially in elder-ly persons; this could be a reason to insist that the patientat least drink water.

CONCLUSION

It has been my experience that the overwhelmingmajority of patients with either type 1 or type 2 diabetescan, from the perspective of blood glucose control, safelyfast on Yom Kippur or one of the other Jewish fast days.In the absence of any previously published guidelines, Ihave outlined my approach to adjusting the currentlyavailable hypoglycemic agents, with the main objectivebeing to avoid hypoglycemia. I have described severalconcepts that should help clinicians advise patients whennew hypoglycemic agents become available. Finally, Iwould recommend that clinicians be proactive and, in thefall of the year, ask their Jewish patients with diabetes ifthey would like to discuss changes in their medication sur-rounding Yom Kippur. This discussion would prevent thepatient from relying solely on personal judgment and pos-sibly taking too much medication, with the resultant devel-opment of hypoglycemia. It also would send a message topatients, who might be hesitant to ask, that fasting on YomKippur is something that can be done safely.

ACKNOWLEDGMENT

I thank Rabbi Mordechai Willig, Rabbi of YoungIsrael of Riverdale, Bronx, New York, and Professor ofTalmud at Yeshiva University, New York, New York, ingeneral for his ongoing advice on religious issues that Iencounter in my medical practice and in particular for hisreview and assistance in preparing this manuscript.

DISCLOSURE

The author has no conflicts of interest to disclose.

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