Coping With Diarrhea After a Glucose Tolerance Test
The glucose tolerance test is an important screening tool used to diagnose diabetes and prediabetes. It involves drinking a sugary glucose drink and having your blood sugar measured at intervals afterwards.
One of the most common side effects of this test is diarrhea after drinking the sweet glucose beverage. This can range from mild to severe, leaving you searching for the nearest restroom.
If you experience diarrhea or other gastrointestinal issues after a glucose test, there are some remedies and tips that can help alleviate your symptoms.
Why Does the Glucose Test Cause Diarrhea?
The oral glucose tolerance test (OGTT) involves drinking a concentrated sugar solution on an empty stomach. The standard dose is 75 grams of glucose for adults or 1.75 grams per kilogram of body weight for children.
This large, sudden influx of sugar in your digestive tract can pull fluid into your intestines through osmosis. It also speeds up movement within your gut.
Together, these effects can lead to cramping, bloating, and loose stools or diarrhea in sensitive individuals. The laxative effect is your body's way of quickly expelling the excess glucose from your system.
How Long Does Glucose Test Diarrhea Last?
For most people, glucose test diarrhea starts within a few hours of drinking the sugary solution. Symptoms can come on suddenly and be severe, especially after larger 100-gram glucose doses.
However, the laxative effect tends to be short-lived. Diarrhea and other digestive symptoms usually resolve within 24 hours as the glucose solution moves through your system.
Let your doctor know if diarrhea persists more than 1–2 days after your glucose test or is accompanied by symptoms like fever, blood in stool, dizziness, or severe pain.
Tips to Manage Glucose Test Diarrhea
Here are some tips to help manage diarrhea and stomach issues after an oral glucose tolerance test:
Stay Hydrated
Diarrhea can lead to dehydration as fluid is pulled into your bowels and lost through frequent trips to the bathroom. Be sure to sip water, electrolyte drinks, or broth steadily throughout the day.
Choose Bland Foods
Go for bland, gentle foods until symptoms subside. The BRAT diet including bananas, rice, applesauce, and toast is a good place to start. Other good options are crackers, boiled potatoes, yogurt, and oatmeal.
Avoid Certain Foods
Stay away from foods that may worsen diarrhea like caffeine, alcohol, sugary drinks, dairy, fatty foods, and high-fiber foods. Stick to foods that are easy on your stomach.
Try Over-the-Counter Anti-diarrheals
Anti-diarrheal medications like loperamide (Imodium) and bismuth subsalicylate (Pepto-Bismol) can help control diarrhea episodes. Use as directed.
Consider Probiotics
Probiotic supplements contain beneficial gut bacteria that can help reduce diarrhea. Look for broad-spectrum formulas with billions of CFUs.
Practice Self-care
Get plenty of rest, relax with hot packs or baths, meditate, and treat yourself gently until it passes. Stress can worsen gastrointestinal issues.
Call Your Doctor if Symptoms Persist
Contact your healthcare provider if you have severe diarrhea lasting over 24 hours, bloody stool, dizziness, fever, or severe pain. You may need IV fluids or medical treatment.
Why the Glucose Tolerance Test Is Done
The oral glucose tolerance test is primarily used to test for diabetes and prediabetes.
It can also sometimes be used to diagnose other conditions like insulin resistance, pancreatic disorders, and pituitary gland disorders (1).
Here’s a closer look at why your doctor may order this test:
Diagnosing Diabetes
The OGTT is one of the standard tests used to diagnose type 1 and type 2 diabetes. It's more sensitive than fasting blood sugar testing alone.
If your blood sugar is above 200 mg/dL two hours after drinking the glucose solution, you are diagnosed with diabetes.
Assessing Prediabetes
This test can also detect prediabetes, a condition involving blood sugar levels that are higher than normal but not high enough yet for a diabetes diagnosis.
Blood sugar of 140–199 mg/dL two hours after the glucose drink indicates prediabetes.
Monitoring Diabetes Treatment
Your doctor may occasionally repeat the glucose tolerance test to monitor progression of diabetes and how well treatment is working to control blood sugar levels.
Screening During Pregnancy
Pregnant women are often given a glucose screening test between 24-28 weeks gestation to check for gestational diabetes, which involves high blood sugar during pregnancy.
Preparing for the Glucose Tolerance Test
Proper preparation is important prior to the oral glucose tolerance test. This helps ensure you get accurate test results.
Here are some key tips on how to prepare (2):
Fast for 8–14 Hours
You must fast for 8 to 14 hours beforehand to ensure stable baseline blood sugar levels. Only drink plain water during this time. Avoid food, drinks, gum, candy, etc.
Check with Your Doctor
Talk to your doctor about any medications you take. You may need to adjust the timing of certain diabetes medications before the test.
Arrive Early
Be sure to arrive early so the test can be completed properly after the required fasting period.
No Smoking or Exercising Beforehand
Avoid smoking and exercising right before the test, as this can impact results.
Minimize Stress
Try to relax. Stress hormones can affect your blood sugar levels.
Come Prepared
The test takes 2-3 hours, so bring a book, headphones or something else to help pass the time. Having diarrhea remedies on hand may also be useful.
What to Expect During the Test
Wondering what happens during the standard oral glucose tolerance test?
Here is a step-by-step overview of what you can expect:
Baseline Blood Draw
A blood sample will first be taken to measure your baseline blood sugar levels after fasting.
Drinking the Glucose Solution
Next, you will drink a sugary glucose solution within a 5-minute period. The standard adult dose is 75 grams of glucose dissolved in water.
Let your provider know right away if you have trouble tolerating or keeping the drink down.
Blood Samples at Intervals
Your blood sugar will be checked 1 hour after drinking the solution, and again at the 2-hour mark. Sometimes a third sample is taken after 3 hours.
Infants and children may require blood draws more frequently, such as every 30 minutes for 2 hours.
Monitoring Symptoms
Your provider will monitor for signs of hypoglycemia like shakiness, nausea, sweating, anxiety, headache, and dizziness after the glucose drink. Let them know if you feel unwell.
Interpreting Your Test Results
After the testing period, your blood samples will be analyzed to see how your body responded to the glucose challenge.
Here is an overview of normal and abnormal glucose tolerance test results:
Normal
FAQs
Why does the glucose test cause diarrhea?
The large, concentrated sugar drink can pull fluid into your intestines through osmosis and speed up gut motility, causing diarrhea in some people.
How long does glucose test diarrhea last?
Diarrhea usually starts within a few hours of the test and resolves within 24 hours as the glucose passes through your system.
What helps with glucose test diarrhea?
Tips to manage diarrhea include staying hydrated, eating bland foods, avoiding certain foods, trying OTC medications, taking probiotics, and practicing self-care.
Do you have to fast for the glucose tolerance test?
Yes, you must fast for 8-14 hours before the oral glucose tolerance test for accurate results. Only plain water is allowed.
What are normal glucose test results?
Blood sugar under 140 mg/dL is normal. Between 140-199 mg/dL indicates prediabetes. Over 200 mg/dL at 2 hours confirms diabetes.
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