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Home > Patients and Visitors > Patient Information Library > Guidance for people with diabetes when taking bowel preparation

Guidance for people with diabetes when taking bowel preparation

The aim of this patient information is to help people with type 1 Diabetes Mellitus or type 2 Diabetes Mellitus who are on tablets and/or insulin for their condition. If you have type 2 Diabetes Mellitus managed by diet alone, you do not need to read this patient information.

Guidance for people with diabetes when taking bowel preparationTo view a PDF you may need to download Adobe Reader.

Please read this patient information as soon as possible and well in advance of your appointment.

Aim of the patient information

Moviprep, Plenvu and Picolax/Citrafleet are strong laxatives which will cause diarrhoea, and with the reduction in food volume as part of the endoscopy preparation, your diabetes medications and/or insulin will need adjusting. Please follow the guidelines as shown in this patient information. If you are unsure, or your diabetes medication is not listed, please contact your usual Diabetes Health Care Practitioner for further advice.

It is important to read the ‘How to take your Bowel Preparation patient information’ well in advance of your appointment.

Day before your procedure

  • Have breakfast, keeping to the low fibre diet found in the ‘How to take your bowel preparation’ patient information. Please try to include white bread or white rice with this meal.
  • Refer to the ‘How to take your bowel preparation’ patient information for when to stop eating. This is different for a morning and afternoon appointment.
  • Drink plenty of clear fluids from the list given.
  • Check your blood glucose levels on a regular basis (if you have a monitor).
  • You should have clear sugary fluids as listed in the accompanying bowel preparation instructions, if needed, to treat or avoid a ‘hypo’.

What to do if you have a hypo whilst fasting

  • If your blood glucose is below 4mmol/L, treat with 4 glucose tablets OR 4-5 teaspoons sugar OR a 200ml carton of clear apple juice.
  • Test your blood glucose after 10-15 minutes and if it is still below 4mmol/L repeat the glucose treatment. Hypo treatment can be repeated up to 3 times if your blood glucose stays below 4mmol/L. If you have a hypo during the 2-hour time when you are not allowed to eat and drink, please treat with glucose tablets or sugar as above.
  • Continue to monitor blood glucose levels hourly, until after the procedure.
  • Please make the endoscopy staff aware if you have had hypos whilst preparing for your procedure.

For patients taking insulin only

Biphasic mixed insulin/Twice daily

(Novomix 30, Humulin M3, Humalog Mix25, Humalog Mix50, Insuman Comb25, Insuman Comb50)

Day before procedure

  • Reduce evening dose by half.

MORNING appointment – day of procedure

  • Take half your usual morning dose.
  • Take your usual dose in the evening.

AFTERNOON appointment – day of procedure

  • Take half your usual morning dose.
  • Take your usual dose in the evening.

Day after procedure

  • Take usual dose of insulin.

Basal Bolus short acting insulin

Actrapid, Apidra, Fiasp, Humalog, Humulin S, Insuman Rapid, Lyumjev, Novorapid

Day before procedure

  • Take your usual dose of insulin with evening meal.

MORNING appointment – day of procedure

  • Do not take your morning dose of insulin.
  • Take usual dose at lunch if eating and drinking (bring your insulin and a sandwich with you).
  • Take usual dose with evening meal if eating and drinking.

AFTERNOON appointment – day of procedure

  • Take usual morning dose of insulin (this can be reduced by 50% if glycaemic control is tight).
  • Do not take lunchtime dose.
  • Take usual dose with evening meal if eating and drinking.

Day after procedure

  • Take usual dose of insulin.

Basal (long‑acting) insulins

Abasaglar, Humulin I, Insulatard, Insuman Basal, Lantus, Levemir, Semglee, Toujeo, Tresiba

If taken in the morning:

Day before procedure

  • Take your usual dose of insulin.

MORNING appointment – day of procedure

  • Reduce insulin dose by half.

AFTERNOON appointment – day of procedure

  • Reduce insulin dose by one third.

Day after procedure

  • Take usual dose of insulin.

If taken in the evening:

Day before procedure

  • Reduce insulin dose by half.

Day of procedure – ALL appointments

  • Take usual dose of insulin.

Day after procedure

  • Take usual dose of insulin.

Patients with Type 1 Diabetes MUST NOT OMIT basal insulin

For patients taking tablets and/or GLP-1 medication or injections for diabetes control

Acarbose

Day before:               Do not take

Day of procedure:    Do not take

Day after:                   Take as usual

Metformin

Day before:               Take morning dose only. Do not take evening dose

Day of procedure:    Do not take morning dose. Take evening dose as usual

Day after:                   Take as usual

Repaglinide/Nataglinide

Day before:               Do not take

Day of procedure:    Do not take

Day after:                   Take as usual

Sulphonylureas

(Gliclazide, Glibenclamide, Glipizide, Glimepiride, Gliquidone)

Day before:               Do not take

Day of procedure:    Do not take in the morning. Take as usual in the evening

Day after:                   Take as usual

Pioglitazone

Day before:               Do not take

Day of procedure:    Take as usual

Day after:                   Take as usual

SGLT2 inhibitors

(Dapagliflozin, Canagliflozin, Empagliflozin)

Day before:               Do not take

Day of procedure:    Do not take

Day after:                   Take as usual

DPP‑IV inhibitors

(Sitagliptin, Saxagliptin, Vildagliptin, Alogliptin, Linagliptin)

Day before:               Do not take

Day of procedure:    Do not take

Day after:                   Take as usual

GLP‑1 injections and tablets

(Trulicity, Exenatide (Byetta), Liraglutide, Rybelsus, Lixisenatide, Semaglutide (Ozempic), Tirzepatide (Mounjaro)

Weekly injections:                Stop 1 week prior to procedure if possible

Daily injections or tablets:   Do not take the day before the procedure

Day of procedure:

If a weekly injection is due today: Do not take

Daily injections or tablets:               Do not take

Day after the procedure:

Weekly injection:                  Take today if it was due on the day of procedure

Daily injections or tablets:   Take as usual

Continuous Subcutaneous Insulin Infusion (CSII) & Hybrid Closed Loop (HCL) pump users

  • Refer to the ‘How to take your bowel preparation’ patient information as to when to stop eating
  • Drink plenty of clear fluids. Follow the accompanying bowel preparation instructions
  • Users of CSII may need to use a temporary basal of – 25-50% to maintain a blood glucose of 5-10mmol/l
  • HCL pump users’ basal level should be adjusted in line with glucose level
  • Insulin carbohydrate ratios (ICRs) may need reducing during preparation for your procedure
  • Your insulin pump should remain in-situ throughout your procedure
  • If unsure, please contact your specialist pump team for advice

Useful contact numbers

For appointments and general enquiries (8.30am to 5.00pm Monday to Friday). Our booking service covers all sites so please ring any of the numbers below

01205 445072

01476 464366

01522 573849

For procedure related enquiries (8.30am to 6.00pm Monday to Friday)

Boston           01205 446559

Grantham      01476 464085

Lincoln           01522 573016

Louth              01507 631236

For more information please see: www.ulh.nhs.uk/services/endoscopy

BOWEL CANCER SCREENING PROGRAMME PATIENTS: Please ring 01522 597548 for all enquiries