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Diabetes: Adjusting your medicine and diet for a barium enema or colonoscopy

Diabetes

Adjusting your diabetes medicine and diet for a barium enema or colonoscopy

The guidelines below will help you adjust your diet and diabetes medicine as you get ready for your barium enema or colonoscopy.

If you see a diabetes educator or diabetes specialist, contact them at least 1 week before your test to ask about adjusting your diabetes medicine or insulin.

Diet

Follow the instructions the gastroenterology (GI) clinic gives you about what you can eat or drink before the test.
Do not eat or drink any of the following:
- milk products or substitutes such as soy, almond, or goat milk
- meal replacements like Boost or Ensure
- alcohol
Treat the clear fluid days like a sick day. Use List 1 or List 2 in the table below to choose what to eat and drink. Your diet can be changed to clear fluids in one of these ways:
- If you count carbohydrates, try to drink the same amount of carbohydrates as you would eat at each meal and snack.
- If you follow a meal pattern, any item from List 1 will replace 1 serving from the grains and starches, fruit, milk and alternatives, or other choices group.
- If you don’t follow a special diet or meal plan, eat or drink 1 item from List 1 every hour.
If your glucose (sugar) drops below 4.0 mmol/L or if you have symptoms of low glucose, take 15 grams of a carbohydrate-containing fluid from List 1. Test your glucose again in 15 minutes. If your glucose is still low, take another 15 grams of carbohydrate-containing fluid from List 1.
If you’re worried your glucose will run too low, take extra fluid from List 1.

List 1: Fluids that have sugar. Each has about 15 grams of carbohydrates. Do not drink any fluids with red or purple dye.	List 2: Fluids that are sugar-free. Choose as desired. Do not drink any fluids with red or purple dye.
black tea, coffee, or water with 1 rounded tablespoon (15 mL) sugar or honey ½ cup (125 mL) regular Jell-O ½ cup (125 mL) regular (sugar sweetened) Kool-Aid ¾ cup (175 mL) fruit drink or fruit juice without pulp (such as apple or white grape) ¾ cup (175 mL) regular pop (such as ginger ale) 1 cup (250 mL) sports drinks (such as Gatorade) 50 mL juice popsicle	water clear bouillon, broth, or consommé diet pop (such as diet ginger ale) diet Kool-Aid or Crystal-Lite black coffee or tea diet popsicle diet Jell-O

Monitoring your glucose at home

Monitor glucose anytime you feel your glucose is low or high.

Test your glucose at least every 4 hours. Glucose values in the range of 8.0 to 12.0 mmol/L are fine for these 2 days before the test, even if it’s higher than your usual target.
If you have type 1 diabetes or you are on an SGLT2 inhibitor - canagliflozin (Invokana), dapagliflozin (Forxiga), empagliflozin (Jardiance) - and combination medicines that contain any of these medicines (such as with metformin) and your glucose values are over 14.0 mmol/L, test your urine or blood for ketones.
- If you have type 1 diabetes and are positive for ketones, you may need extra insulin.
- Moderate to large ketones may mean that you’re in DKA (diabetic ketoacidosis). Go to the emergency department right away.
If you’re worried about your glucose levels, speak with your healthcare provider or diabetes educator.

Adjusting your diabetes medicine

If you take diabetes medicine other than insulin

2 days before your test

If you are on an SGLT2 inhibitor - (canagliflozin (Invokana), dapagliflozin (Forxiga), empagliflozin (Jardiance) - or combination medicines that contain any of these medicines (such as with metformin), do not take.
Take your other diabetes medicine as usual.

The day before your test

If you are on an SGLT2 inhibitor - canagliflozin (Invokana), dapagliflozin (Forxiga), empagliflozin (Jardiance) - or combination medicines that contain any of these medicines (such as with metformin), do not take.
Take your other diabetes medicine as usual or as your healthcare provider tells you.
If you are on repaglinide (Gluconorm), gliclazide (Diamicron, Diamicron MR), or glyburide (Diabeta), speak to your healthcare provider as your dose or doses may need to be lowered.

The day of your test

Don’t take any diabetes medicine until after your test is done and you’re eating. Then take it as per your scheduled dose.
Bring a source of fast-acting sugar and your glucose monitor with you

If you take insulin

The day before your test

Morning

Basal insulin: Reduce your dose of basal insulin (Basaglar, Humulin N, Lantus, Levemir, Novolin NPH, Semglee, Toujeo, or Tresiba) by 20% or the amount your healthcare provider tells you. You may need to reduce Tresiba 2 to 3 days before the test. Talk with your healthcare provider. Write out your dose so that it is easier to remember: Your dose will be __________ units.
Premix insulin: Reduce your dose of premix insulin (Humulin 30/70, Novolin 30/70, or Humalog 25/75) by 20% or the amount your healthcare provider tells you for your breakfast meal. Write out your dose so that it is easier to remember: Your dose will be __________ units.
Insulin pump: Keep the same basal rate.

Meals

Bolus (meal) insulin: Reduce your dose of bolus (meal) insulin (Admelog, Apidra, Fiasp, Humalog, Humulin R, Kirsty, NovoRapid, Novolin Toronto, or Trurapi) by 20% or the amount your healthcare provider tells you. You may need to reduce your dose of these meal insulins more if your glucose becomes low. Write out your dose so that it is easier to remember: Your dose will be __________ units.
Premix insulin: Reduce your dose of supper premix insulin (Humulin 30/70, Humalog 25/75, Humalog Mix 50, Novolin 30/70, Novolin 40/60, Novolin 50/50) by 20% or the amount your healthcare provider tells you. Write out your dose so that it is easier to remember: Your dose will be __________ units.

Evening/bedtime

Basal insulin: Reduce your dose of basal insulin (Basaglar, Humulin N, Lantus, Levemir, Novolin NPH, Semglee, Toujeo, or Tresiba) by 20% or the amount your healthcare provider tells you. You may need to reduce Tresiba 2 to 3 days before the test. Talk with your healthcare provider. Write out your dose so that it is easier to remember: Your dose will be __________ units.
Insulin pump: You may need to reduce your basal rate by 10% to 20% overnight if there are concerns about low glucose. If there are no concerns, keep the same basal rate.

The day of your test

Bring a source of fast-acting sugar and your glucose monitor to the test with you.

Morning

Bolus (meal) insulin: Do not take your morning meal (bolus) insulin (Admelog, Apidra, Fiasp, Humalog, Humulin R, Kirsty, NovoRapid, Novolin Toronto, or Trurapi).
Premix insulin: Do not take your morning premix insulin (Humulin 30/70, Humalog 25/75, Humalog Mix 50, Novolin 30/70, Novolin 40/60, Novolin 50/50).
Basal Insulin: Reduce your dose of basal insulin (Basaglar, Humulin N, Lantus, Levemir, Novolin NPH, Semglee, Toujeo, or Tresiba) by 20% or the amount your healthcare provider tells you. You may need to reduce Tresiba 2 to 3 days before the test. Talk with your healthcare provider. Write out your dose so that it is easier to remember: Your dose will be __________ units.
Insulin pump: You may need to reduce your basal rate by 10% to 20% overnight if there are concerns about low glucose. If there are no concerns, keep the same basal rate.

After the test

Premix insulin: Reduce your morning dose of premix insulin (Humulin 30/70, Humalog 25/75, Humalog Mix 50, Novolin 30/70, Novolin 40/60, Novolin 50/50) by 20% or the amount your healthcare provider tells you for your first meal after the test. Write out your dose so that it is easier to remember: Your dose will be __________ units.
All other insulin: Take as prescribed.

To see this information online and learn more, visit MyHealth.Alberta.ca/health/pages/conditions.aspx?Hwid=custom.ab_diabetes_bariumenema_colonoscopy.

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Current as of: July 19, 2023

Author: Endocrinology and Metabolism Program, Alberta Health Services

This material is not a substitute for the advice of a qualified health professional. This material is intended for general information only and is provided on an "as is", "where is" basis. Although reasonable efforts were made to confirm the accuracy of the information, Alberta Health Services does not make any representation or warranty, express, implied or statutory, as to the accuracy, reliability, completeness, applicability or fitness for a particular purpose of such information. Alberta Health Services expressly disclaims all liability for the use of these materials, and for any claims, actions, demands or suits arising from such use.

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