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Managing Type 2 Diabetes During Religious Fasting

Type 2 diabetes (T2D) is a condition in which the body cannot regulate blood sugar (glucose) levels properly. This happens because the body either does not produce enough insulin or becomes resistant to its effects. People with T2D need to manage their glucose levels to stay healthy.1

Many people living with T2D want to engage in religious observances that call for fasting. For them, fasting is an important way to engage with their religion or spirituality. But fasting affects glucose levels. So people with T2D must be very careful to fast safely.2

Fasting is generally safer for people with type 2 than for people with type 1 diabetes. But those with T2D who wish to fast still need to understand its possible dangers.3

What is religious fasting?

Fasting involves eating no food, and sometimes drinking no liquids, for a specific period. A fast typically lasts between 6 and 24 hours.4

Many religions around the world call for fasting on certain holidays or times of the year. Religions that may observe fasting include:5

  • Islam
  • Christian Orthodox
  • Judaism
  • Hinduism
  • Buddhism
  • Jainism

For example, Muslims often fast between sunrise and sunset each day during the month of Ramadan. This is known as long-term intermittent fasting. Other religions may call for shorter overall periods of fasting, such as a single day each week, month, or year. The Jewish holiday of Yom Kippur is an example of a single-day fast.3,6

Risks of fasting with T2D

Your body relies on glucose for energy. It stores extra glucose (in the form of glycogen) in your liver and muscles for later use. During periods of fasting, you are not taking in sugars from foods. This lowers your glucose level. After several hours of fasting, your body will begin to use up its glucose stores to keep its systems running.6,7

People who are generally healthy and whose diabetes is well controlled may have no negative effects from fasting. But without proper nutrition from their diet, anyone’s glucose levels can enter a dangerous zone.2

Glucose levels becoming too low (hypoglycemia)

Not eating leads glucose levels to drop and glucose stores to be used up. This can be dangerous for people with T2D. If a fast continues for too long, your body may eventually use up the glucose it needs for brain function.2,3

Symptoms of low glucose include:2,3

  • Shakiness
  • Sweating
  • Pale skin
  • Irregular heartbeat

Blood becoming too acidic (ketoacidosis)

Along with the amount of glucose, the amount of insulin in your blood decreases when you fast. If the body does not have enough insulin to use its glucose, or if it has used up all of its glucose stores, it will begin to break down body fat for energy. This process releases acids called ketones into the blood.3,6,8

If the blood becomes too acidic, this is known as diabetic ketoacidosis (DKA). DKA can be life-threatening, and it requires emergency medical care. This condition is more of a concern for people living with type 1 diabetes. But those with T2D should be aware of the risk.3,6,8

Symptoms of DKA include:8

  • Shortness of breath
  • Abdominal pain
  • Nausea
  • Vomiting

Glucose levels becoming too high (hyperglycemia)

When a person with T2D fasts, their liver may begin to put out too much glucose. Or they may reduce their diabetes medicine to avoid low glucose, but reduce it too much. Both of these situations can result in glucose levels getting too high. This is another possible cause of DKA.3,5,6,8

Symptoms of high glucose include:6

  • Fatigue
  • Extreme thirst
  • Urinating more than usual

Dehydration

Keeping your body fluids at the right level (hydration) is important at all times. Fasting from eating and drinking can lead to dehydration. High glucose and certain medicines also can lead to dehydration. To keep you from becoming dehydrated, your doctor may recommend against fasting if:4,6

  • You have an A1C of 9 or higher
  • You currently have signs of illness (such as a fever)

Dehydration lowers blood pressure. This can have serious health effects. For example, low blood pressure puts people who have recently had a heart attack or stroke at higher risk of having another one. One sign of dehydration during fasting is a headache that begins soon after the fast does.4,7

Possible benefits of fasting with T2D

Some people with T2D may find that the possible benefits of fasting outweigh the risks.4

Physical health benefits

Studies of animals suggest that intermittent fasting may have several positive effects on physical health, including:7

  • Lower blood pressure
  • Reduced body fat
  • Increased insulin sensitivity
  • Delayed progression diseases that affect the nerves (neurological diseases) like Alzheimer’s and Parkinson’s
  • Protection against developing diabetes and heart disease

In particular, short periods of fasting may help pregnant people with gestational diabetes become more sensitive to insulin. This can help regulate their glucose levels.4

Mental health benefits

For many people, fasting is an important spiritual practice. Observing religious traditions can provide a sense of purpose and connection. Some people seek to learn self-restraint or empathy from fasting.3,5

Tips for safe religious fasting

If you have T2D and want to fast for religious reasons, make sure you do so safely. Always talk to your doctor about possible risks and benefits before fasting. Your doctor can help you make a plan that is safe for you. The plan may include adjusting your diabetes medicine before and after fasting.4

Your doctor may refer you to a diabetes educator for further education on safe fasting. Studies have shown that diabetes education can help keep people with diabetes healthy during periods of religious fasting. For instance, diabetes education for people with T2D who fasted during Ramadan led to lower rates of hypoglycemia and improvement in A1C.5

Here are some general tips for safe fasting:2,6

  • Before beginning a fast, eat a nutritionally balanced meal made up of foods with a lower glycemic index.
  • When breaking the fast, start with foods low in sugar or fat that will not cause your glucose to spike.
  • If the fast allows, continue to drink water and other hydrating fluids. Avoid caffeine and other dehydrating drinks. If you cannot drink during the fast, hydrate well before and after the fast.
  • Monitor your glucose continuously throughout the fast.
  • If glucose reaches a dangerous level, break the fast immediately and begin your usual treatment. Your doctor will tell you what a dangerous level for you is.

Other things to know

For people with T2D, fasting requires careful planning. Whether or not to fast is a personal decision that should be made between you and your doctor. Most religions do not require people with significant health problems to fast. So you may be able to decline if it is not safe for you.6

Certain groups should take extra caution when fasting. The practice may be especially dangerous for:2,3,5,6

  • People with T2D who have poor glucose control or who take certain types of insulin
  • Children
  • People who are pregnant or breastfeeding
  • Older adults
  • People with a history of repeated hypoglycemia
  • People with diseases of the kidney or blood vessels

Tell your doctor about all of your health conditions and medicines before beginning a fast. If you begin to feel any symptoms of low or high glucose, stop fasting and begin treatment right away.2

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