Gastroenterology/Diabetes Service - Specific instructions for people with Type 2 diabetes undergoing a colonoscopy

If your diabetes is treated by diet alone

Please follow the instructions given to you to prepare you for your colonoscopy.

If your diabetes is treated by tablets

Diabetes Medication: Metformin
On the day before your test: Do not take your tablets.
On the day of the test: Do not take until the next meal after your test.

Diabetes Medication: Gliclazide or Glimepiride
On the day before your test: Do not take your tablets
On the day of the test: Take after the test, at the time that you are next due to take them.

Diabetes Medication: Alogliptin, Linagliptin, Sitagliptin, Saxagliptin, Vildagliptin
On the day before your test: Take your tablet as usual
On the day of the test: Take your tablets as usual. If you have been told to fast, take the tablet after your test

Diabetes Medication: Pioglitazone
On the day before your test: Take your tablet as usual.
On the day of the test: Take your tablets as usual. If you have been told to fast, take the table after your test.
 
Diabetes Medication: Empagliflozin, Canagliflozin, Dapagliflozin
On the day before your test: Do not take your tablet for 3 days prior to the test
On the day of the test: Do not take your tablet. Start taking your tablet as usual on the day after the test, if you are eating and drinking as usual.

If you take injectable treatment (NOT insulin) for your Diabetes

Diabetes Medication: Victoza (Liraglutide) Lyxumia (Lisixenatide) (daily injection)
In the week prior to the test: Do not take your injection in the 3 days prior to the test
On the day of your test: Do not take your injection. Start taking your injection as usual on the day after the test.

Diabetes Medication: Trulicity (Dulaglutide), Bydureon (Exenatide), Semaglutide (Ozempic), Tirzepatide (Mounjaro) (weekly injection)
In the week prior to the test: Omit your injection in the week prior to your test (ideally 2 weeks if possible)
On the day of your test: If your injection is due on this day, delay taking it until the day after your test.

If you take insulin for your diabetes

Insulin: Humulin I
On the day before the test: Take half your usual dose at the normal time.
On the day of the test: Take half your usual dose on the morning of the test. After the test, take your usual dose at the normal time. If you have been told to fast, do not take your insulin (usual dose) until after the test, at the time you would usually take the next dose of insulin

Insulin: Lantus, Levemir, Semglee, Toujeo, Tresiba
On the day before the test: Take your usual dose of insulin at the normal time
On the day of the test: Take your usual dose of insulin at the normal time

Insulin: Humulin M3, Novomix 30, Humalog Mix 25, Humalog Mix 50
On the day before the test: Take half your usual dose of insulin at the normal time.
On the day of the test: Do not take your insulin (usual dose) until after the test, at the time you would usually take the next dose of insulin.

If you have Type 1 diabetes and take multiple insulin injections

• Only take mealtime insulin when you are eating as usual
• DO NOT MISS taking your long-acting insulin

Testing your blood glucose level - If you already test your blood glucose level

If you currently test your blood glucose level, increase the number of times you test on the day before and on the day of your test to every 2-4 hours, depending on how stable your blood glucose levels are. Your blood glucose levels may be higher or lower than usual during the days around your test. If they do not return to your usual levels after 3 days, then please contact the nurse who looks after your diabetes care.

Hypoglycaemia (Hypo)

If you take insulin or gliclazide or glimepiride as part of your diabetes treatment, you could experience hypo. This occurs when your blood glucose falls too low below 4mmol/l.

If this happens you are likely to feel sweaty, shaky or dizzy. If you can test your blood glucose level and it is below 4mmol/l, follow the advice below immediately:

1. Take 200mls of apple juice and wait for 10 minutes.
2. Retest your blood glucose level and if still below 4mmol/l take another 200mls of apple juice, wait for 10 minutes and retest your blood glucose level.
3. Continue to test your blood glucose every 10 minutes and take 200mls apple juice until your blood glucose is above 4mmol/l.
4. Once your blood glucose level is above 4mmol/l continue to follow the advice to prepare you for the test.

Remember your BG level needs to be 5mmol/l or above to drive.

We recommend that you take your BG meter and hypo treatment with you to the appointment.

If you need further advice from the diabetes team and have a Salford GP, please contact: 0161 206 8802 before you are due to start the preparation for your test.

If your GP is outside Salford, please contact your local diabetes team or practice nurse or GP.