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Diabetes

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

​The guidelines below will help you adjust your diabetes medicine and diet as you get ready for your test.

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.
  • Treat the clear fluid days like a sick day. Use List 1 or 2 on the next page 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 carbohydrate 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 blood sugar drops below 4.0 mmol/L or if you have symptoms of low blood sugar, take 15 grams of a carbohydrate-containing fluid from List 1. Test your blood sugar again in 15 minutes. If your blood sugar is still low, take another 15 grams of carbohydrate-containing fluid from List 1.
  • If you’re worried your blood sugar will run too low, take extra fluid from List 1.
List 1 - Fluids that have sugar (Each has about 15 grams of carbohydrates)(No fluids with red or purple dye.)List 2 - Fluids that are sugar-free​ (Choose as desired)(No 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 (e.g., apple, white grape)
  • ¾ cup (175 mL) regular pop
  • 1 cup (250 mL) sports drinks (e.g., Gatorade®)
  • water
  • clear bouillon, broth, or consommé
  • diet pop
  • diet Kool-Aid® or Crystal-Lite®
  • black coffee or tea
  • diet popsicle
  • diet Jell-O®

Testing your blood sugar

Test your blood sugar anytime you feel your blood sugar is low or high.

  • Test your blood sugar at least every 4 hours. Blood sugars in the range of 8 to 12 mmol/L are fine for these 2 days, even if it’s higher than your usual target.
  • If you have type type 1 diabetes or you are on an SGLT2 inhibitor canagliflozin (Invokana), dapagliflozin (Forxiga), empagliflozin (Jardiance) and ertugliflozin (Steglatro) and your sugars are over 14 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) and need to go to the Emergency Department right away.
  • ​If you’re worried about your blood sugar level, speak with your healthcare provider or diabetes educator.
  • Adjusting your diabetes medicine

    If you take insulin

    The day before the test

    Morning

    • Basal Insulin: Reduce your dose of basal insulin (Humulin N, Novolin NPH, Lantus, Basaglar, Toujeo, Levemir or Tresiba) by 20% or the amount your healthcare provider tells you. Tresiba may need to be reduced for 2-3 days before the procedure. Talk with your healthcare provider.
      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. Your dose will be units.
    • Insulin Pump: Keep the same basal rate.

    Meals

    • Bolus (meal) Insulin: Reduce your dose of bolus (meal) insulin (Apidra, Humalog, NovoRapid, Fiasp, Humulin R, or Novolin Toronto) by 20% (or the amount your healthcare provider tells you). You may need to reduce your dose of these meal insulins more if your blood sugar becomes low. Your dose will be units.
    • Premix Insulin: Reduce your dose of supper premix insulin (Humulin 30/70, Novolin 30/70, or Humalog 25/75) by 20% (or the amount your healthcare provider tells you). Your dose will be units.

    Evening/Bedtime

    • Basal Insulin: Reduce your dose of basal insulin (Humulin N, Novolin NPH, Lantus, Basaglar, Toujeo, Levemir or Tresiba) by 20% or the amount your healthcare provider tells you. Tresiba may need to be reduced for 2-3 days before the procedure. Talk with your healthcare provider.
      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 blood sugar. If there are no concerns, keep the same basal rate.
    Test day

    Morning

    • Bolus (meal) Insulin: Don’t take your morning meal (bolus) insulin (Apidra, Humalog, NovoRapid, Fiasp, Humulin R, or Novolin Toronto).
    • Premix Insulin: Don’t take your morning premix insulin (Humulin 30/70, Novolin 30/70, or Humalog 25/75).
    • Basal Insulin: Reduce your dose of basal insulin (Humulin N, Novolin NPH, Lantus, Basaglar, Toujeo, Levemir or Tresiba) by 20% or the amount your healthcare provider tells you. Tresiba may need to be reduced for 2-3 days before the procedure. Talk with your healthcare provider.
      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 blood sugar. If there are no concerns, keep the same basal rate.

    *Be sure to bring a source of fast-acting sugar and your blood glucose meter with you.

    After the test

    • Premix Insulin: Reduce your morning 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 first meal after the test. Your dose will be units.
    • All other insulin: Take as prescribed.

    If you take diabetes medicine other than insulin

    The day before the test
    • Take your medicine as usual in the morning and at lunch 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(s) may need to be lowered.
    Test day
    • Don’t take any diabetes medicine until after your test is done and you’re eating. Then take it as per your scheduled dose.

    *Be sure to bring a source of fast-acting sugar and your blood glucose meter with you.

    For 24/7 nurse advice and general health information call Health Link at 811.

Current as of: July 10, 2020

Author: Endocrinology and Metabolism Program, Alberta Health Services