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    Diabetes: How to Prepare for a Colonoscopy - Topic Overview

    Managing blood sugar and medicines

    Your doctor may have you track your blood sugar for at least 24 hours before and 72 hours after your test.

    Plan on bringing your blood sugar meter and test strips with you to the test. Also, have glucose tablets or other quick sugar food with you in case your blood sugar drops too low.

    If you take pills or insulin, your doctor will give you exact instructions about how to take your medicines. You may need to change your diabetes treatment before and after the procedure.

    Everyone is different. It's important to talk with your doctor if you don't understand what to do with your medicines. Get the instructions in writing, and bring them with you to the test.

    Generally, if you take:

    • Metformin, your doctor may have you stop taking it 48 hours before and after your colonoscopy.
    • Oral diabetes pills or tablets, your doctor may have you stop taking your medicine on the morning of the test.
    • Short-acting insulin, your doctor may have you stop taking it on the morning of the test.
    • Long-acting insulin, your doctor may have you take only half of your usual dose on the morning of the test.

    Bring your diabetes pills or insulin with you to take after the test as your doctor suggests. Don't take a double dose of medicines you've missed.

    How to eat and drink

    You'll get detailed instructions about food and drink when you get the medicines to cleanse your colon. Generally, the day before the test, you'll only be able to have clear liquids. These include water, tea, coffee, clear juices and broths, gelatin, and sports drinks.

    Work with your diabetes doctor on how best to manage carbohydrate as you prepare for the test. You may want to plan 45 grams of carbohydrate for liquid "meals" and 15 to 30 grams for snacks. Apple or white grape juice and sweetened gelatins are a few options.

    WebMD Medical Reference from Healthwise

    Last Updated: November 14, 2014
    This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.
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