Diabetes Forecast

Safe Fasting With Diabetes

By Erika Gebel Berg, PhD , ,
empty blue plate with fork and knife on either side


Whether you are honoring an ancient religious practice or heading to the lab for a fasting blood test, care is needed when missing meals with diabetes. Fasting can throw off the delicate balance of food, water, and blood glucose levels in potentially harmful ways.

Safety First

Fasting with diabetes poses significant risks, says Kathaleen Briggs Early, PhD, RD, CDE, of the Pacific Northwest University of Health Sciences. Most of the research on fasting and diabetes surrounds Ramadan, the annual Islamic observance that requires fasting from sunrise to sundown for 29 or 30 days. A commentary published in 2010 in Diabetes Care developed in collaboration with the American Diabetes Association (ADA) focused on fasting during Ramadan, though many of the issues it raises are relevant to other types of fasting as well. It says that “most often, the medical recommendation will be not to undertake fasting” if you have diabetes.

The paper acknowledges that fasting for spiritual reasons is a personal decision, but one that should include the guidance of a health care provider. A study found that 43 percent of people with type 1 diabetes and 79 percent of people with type 2 diabetes from 13 Islamic countries fast during Ramadan. With that reality, fasting safely becomes a priority for people with diabetes and their care providers.

“Anybody with diabetes needs to first talk to their doctor about going on a fast,” says Early, and some experts recommend a pre-fasting medical assessment to help ensure safety. If you are considering fasting, talk to your health care provider about a plan that takes medication, nutrition, and hydration into account. Regularly monitoring blood glucose during fasting is key to avoiding health emergencies.

Health Risks

Not eating when taking insulin or certain other diabetes medications can raise the risk of hypoglycemia (low blood glucose). A study of people with diabetes who fasted during Ramadan found that the risk of being hospitalized for hypoglycemia increased by 4.7-fold in people with type 1 diabetes and by 7.5-fold in those with type 2.

Pregnant women and people with a history of hypoglycemia, ketoacidosis (a complication of very high blood glucose), or poor blood glucose control are also considered very high risk. Heavy manual labor and illness may put a person into this group. For religious fasts that require abstinence from water, such as Ramadan, dehydration can raise the risk for serious complications among susceptible people, such as those with kidney or heart disease. “In extreme cases, electrolytes can get out of whack and exacerbate problems,” says Early.

High blood glucose can also be an issue during fasting. People often cut back on medication while fasting to lower the risk of hypoglycemia. With no food, the liver releases stored glucose for energy. Both of these contribute to high blood glucose. In one study, researchers found a fivefold increase in severe hyperglycemia in people with type 2 who fasted during Ramadan and a threefold increase in people with type 1.

Breaking the Fast

Perhaps the most important part of fasting with diabetes is knowing when to quit. Experts recommend always and immediately ending a fast if hypoglycemia (usually defined as a blood glucose level less than 70 mg/dl) occurs. In the case of a low, it’s important to break the fast and treat the low with food or drink that contains carbohydrate

Fasting should also cease with blood glucose levels above 300 mg/dl. Some other signs that it’s time to quit may include “common sense kinds of things,” says Early, so listen to your body. For example, if your urine becomes dark, that’s a sign you’re becoming really dehydrated. “Severe headache, nausea, and vomiting would all be signs that you’d want to break your fast,” says Early. Religious leaders tend to agree that fasts are not meant to create undue hardship or create a life-threatening situation. Finding a deeply meaningful spiritual experience can come from other sources beyond those that put you at risk.

Facets of Fasting

Plan with your provider how to handle these common situations involving fasting

Physiological Fast

Sometimes when doctors talk about a “fast,” they just mean the period that you aren’t eating while you sleep. For example, fasting blood glucose indicates first thing when waking up.

Fasting for Religion

Many religions include fast days, and the methods of fasting vary widely depending on religious observation. Some types of fasts may involve abstaining from food and water for a day or more, while others may require that a particular substance, such as oil or alcohol, be avoided.

Fasting for Medical Reasons

Surgeries and other procedures that require a general anesthetic often require a person to fast due to the risk of inhaling or choking on partially digested food during the procedure; water, however, may be allowed. Some blood tests, such as those for cholesterol, may require a person to not eat for 8 or 12 hours.

Fasting for Health

Some evidence suggests that fasting every other day can have health benefits similar to calorie restriction, though long-term studies have not yet been done. So-called “cleanses” and other fast-like practices are popular in alternative medicine as a way to “detoxify” the body, though scientific evidence does not support this practice.

The Unintended Fast

Sometimes missing a meal happens unintentionally because a person becomes distracted and forgets to eat or is without money to pay for food.

Finding Her Own Meaning

A young woman with diabetes comes to terms with fasting

Yom Kippur is the Day of Atonement, the holiest day of the year in Judaism. Yom Kippur requires an absolute fast: no food and not even a sip of water from sundown to sundown, plus a little extra (oy vey), to last around 25 hours. It can get pretty intense by the end, and, for people with diabetes, it may not be safe to participate. But that’s OK.

“In Judaism, if there is even the slightest doubt about health or if safety is an issue … you may not [fast],” says Gil Steinlauf, senior rabbi of Adas Israel Congregation in Washington, District of Columbia (full disclosure: my rabbi). A Hebrew phrase sums up this principle nicely: Pikuach Nefesh (Saving a Life), interpreted as the idea that most of Jewish law should be set aside to preserve human life. Other religions also typically allow people with certain health conditions to skip the religious observance of fasting.

Steinlauf’s younger daughter, Meirav Steinlauf, knows about Pikuach Nefesh firsthand. She was diagnosed with type 1 diabetes in early 2009. Meirav, 14, had her bat mitzvah last year and is now, according to the Jewish faith, herself accountable for upholding Jewish law. She did try once since her diagnosis to fast on Yom Kippur, but it didn’t go so well. “We were never going to let her do an all-day fast,” says Steinlauf. “She actually decided not to eat breakfast, and by 11 a.m. she was really sick.” So, per Pikuach Nefesh, that was the end of that.

Still, Meirav is determined “to give the day meaning.” Now, on Yom Kippur, she eats, she says, as though down with flu, having small portions of sick day–friendly foods, such as toast, and avoiding dessert. Because of the altered eating pattern, Meirav checks her blood glucose more often than normal. If she goes low, “I won’t have jelly beans,” and instead raises her blood glucose with a less-appealing source of carbohydrate. “I want, not to suffer,” she says, “but I want to understand why I fast.”



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