Diabetes and endoscopy Whakamātaunga kōpiro me kōpiro o raro me he matu huka tōu

It is important to manage your diabetes before having an endoscopy (including colonoscopy, sigmoidoscopy and capsule endoscopy). The information here is to help you do this. Before your appointment, you will also get information from the gastroenterology department doing your procedure to help you prepare your bowel. If the information from your specialist doctor differs from the advice on this page, follow your specialist's advice.

On this page

When to see your healthcare provider

With the advice on this page, most people will be able to manage their diabetes before their procedure. But you must talk to your healthcare provider if you:

  • have recently been admitted to hospital because your diabetes is poorly controlled
  • you are having major problems with low blood glucose (hypoglycaemia).

Low blood glucose (hypoglycaemia)

Some people may need to go to hospital to prepare for their colonoscopy, sigmoidoscopy or capsule endoscopy.

Your endoscopy appointment

Managing your diabetes will probably be easier if you have a morning appointment. If you do not have a morning appointment, phone the number on your booking letter to see if your procedure can be rescheduled to an earlier time.

  • Carefully read and follow the information about food and clear fluids on the pamphlet you have been given on bowel preparation.
  • Do not worry if your blood glucose level is not as well controlled as usual as long as it is above 4mmol/L and below 15mmol/L.
  • Bring your blood glucose monitor, diabetes medications, and insulin and injecting equipment (if you use it), with you to the appointment.
  • Also bring some dextrose tablets or whatever you would normally use to manage hypoglycaemia.

Getting prepared for your appointment

If you take tablets for diabetes

  • If you take empagliflozin (Jardiance), dapagliflozin (Forxiga) or empagliflozin with metformin (Jardiamet), do not take the tablets for 2 clear days before your procedure or on the day of your procedure.

Empagliflozin — My Medicinesexternal link

Empagliflozin with metformin — My Medicinesexternal link

  • Take your other diabetes tablets as normal on the morning of the day before your procedure (Monday, if your procedure is Tuesday, and so on).
  • You can restart your tablets once you are able to eat a meal after your procedure.

If you use insulin

You may need to adjust your insulin. It will depend on how much carbohydrate you have when you are on clear fluids and what your blood glucose levels are.

It is important to monitor your blood glucose levels at least 4 times a day, and more often if you have any symptoms of hypoglycaemia. Know what clear fluids you can use to raise your blood glucose level if it is too low.

Taking carbohydrates in clear fluids

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  • Take your normal dose on the day before the procedure (Monday, if your procedure is Tuesday, and so on).
  • Take half your normal dose on the day of the procedure.
  • If your blood glucose is high after the procedure, have the other half of your usual dose with lunch. Go back to your usual dose the next morning.
  • See below if you are using mealtime insulin as well.

  • Take half your usual dose on the evening before the procedure.
  • Take your normal dose the evening after the procedure.
  • See below if you are taking mealtime insulin as well.

The amount of mealtime insulin you will need depends on how much carbohydrate you get from the clear fluids.

  • Take your normal mealtime insulin at breakfast on the day before the procedure (Monday if your procedure is Tuesday, and so on). From lunchtime onwards you will need a reduced dose (in general, about half your usual dose with lunch and the same with the carbohydrate-containing clear fluids at dinner time).
  • Have no mealtime insulin on the day of the procedure until you are eating and drinking again after your procedure.
  • After the procedure, if your glucose level is high, take half your normal mealtime insulin with a snack. If the level is okay, wait until your next meal (lunch or dinner) and have your normal mealtime dose then.

  • On the day before the procedure take your usual dose in the morning and half your usual dose in the evening with carbohydrate-containing clear fluids.
  • On the day of the procedure take one-third of your usual dose in the morning with carbohydrate-containing clear fluids.
  • You can go back to your normal dose in the evening after the procedure.

Taking carbohydrates in clear fluids

These clear fluids have a similar amount of carbohydrate to one medium slice of bread (15 g of carbohydrate):

  • 150 ml clear unsweetened apple juice
  • 100 ml white grape juice
  • 100 ml of Lucozade
  • 30 ml of clear fruit cordial (not lime)
  • 150 ml lemonade
  • 100 ml clear non-coloured jelly
  • 5 dextrose tablets.

You will digest carbohydrates in clear fluids more quickly than carbohydrates in food, so be sure to spread the fluids through the day. Have some of the fluids listed above as well as the other clear fluids mentioned in your pamphlet at lunchtime, some mid-afternoon, some at dinnertime, some after dinner and some at midnight, depending on your blood glucose readings.

You can also have some of these carbohydrate-containing fluids up to the time written on your procedure information pamphlet. If you need any after that time because your blood glucose is low, let the staff know when you arrive for your procedure.