Healthy Living NT

Religious fasting and diabetes

02/06/2015 Written by Gerard Wong, Dietitian, Darwin

In the dictionary, fasting is defined as the abstinence from or reduction in the intake of certain foods. Fasting for religious or spiritual reasons has been an important part of many religions for hundreds of years, and still is today. There are many different types of fasting; varying in the timing of foods and drinks, the different types allowed and the overall length.

Sunset Fasting DiabetesOne example is the fasting during the month of Ramadan in the Islamic religion. Fasting is between dawn and sunset where Muslims refrain from eating food and drinking fluids. A pre-dawn meal and a larger meal after sunset are eaten each day.

The Greek Lent on the other hand mainly involves an abstinence from certain foods such as meat, dairy, eggs, wine and alcohol with a short fasting period.

People who are acutely unwell or those with chronic disease can opt out from fasting; however some may still choose to participate because of its significance in their religion.

Fasting and diabetes – what can happen?

Fasting for people with diabetes can be safe if there is good planning and management; part of this is understanding what the risks are, so that informed decisions can be made. These include:

  • During fasting, people often experience large swings in their blood glucose levels:
    • Having large meals containing a lot of carbohydrate foods after times of fasting can make blood glucose levels high
    • Taking some diabetes medications and having long gaps between food can make the blood glucose level go low, and with some medications can drop dangerously low
    • It is essential to talk with your doctor about this before fasting 
  • Many fasts include absence of fluid, which can result in dehydration; people with diabetes who fast are at particular risk of dehydration:
    • When blood glucose levels are high your body tries to remove glucose by passing urine – when you are dehydrated you are not passing urine as often

There are some people for whom it may not be safe to fast. These include people with diabetes and who:

  • are prescribed insulin or sulphonylurea without changing their medication regimen
  • have poor blood glucose control
  • have other serious illnesses such as unstable angina or uncontrolled high blood pressure
  • have a history of recurrent diabetic ketoacidosis
  • are pregnant
  • have an acute illness
  •  are doing intense physical activity
  • have renal / kidney problems
  • are elderly people
  • have previously experienced severe problems with blood glucose control during their fasting

Please check with your doctor about this.

If I decide to fast what do I need to do before?

  • Get good control of blood glucose levels BEFORE starting the fast
  • Discuss your fasting plans with diabetes educator and doctor:
    • Check your overall health with your doctor – blood glucose control, blood pressure, blood fat level
    • Talk about any possible changes to your medications – for example the dose or timing of medication may need to change
    • Organise a plan of what to do if your blood glucose level goes too low or too high during the fast
  • Talk with your dietitian about the best foods to eat during your times of non-fasting.

Tips for fasting

Aim to reduce the large swings in blood glucose levels:

  • General healthy eating strategies should still be in place. Therefore, include fruits, vegetables, low fat dairy, lean meat and plenty of water
  • Try to have a good breakfast just before sunrise. This will spread out your energy intake more evenly
  • Try to have more low glycaemic index (GI) carbohydrate foods at the evening meal
  • Limit the amount of sweet foods and drinks eaten after sunset to avoid blood glucose levels going too high
  • Limit deep frying foods and excessive amounts of sweets and refined sugar
  • Discuss further with your dietitian
  • Monitor blood glucose levels regularly as per guidelines from your diabetes educator (essential for people with type 1 diabetes and those with type 2 diabetes on insulin and sulphonylurea medications)

What about physical activity?

  • Physical activity is an important part of a healthy lifestyle and management of diabetes and should be continued during a fast if possible
  • It is best to aim for about 30 minutes of mild-moderate exercise per day; high intensity or excessive exercise can lead to low blood sugar levels and should therefore be avoided during a fast
  • Also consider the weather – in the Northern Territory the climate is very hot a lot of the time – if you are exercising try to do it in the cooler parts of the day or in air conditioning to limit further dehydration
  • It is important to speak with your diabetes educator about monitoring your blood glucose levels before/during/after physical activity

Fasting as part of religious festivals such as Ramadan can be possible for people with diabetes. Please discuss your plans with your doctor and diabetes education team to work out what is manageable for you.


This article was published on the Territory Way edition 111 - March 2013. For more interesting articles please click here

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