What is a Blood Sugar (glucose) Test?

A blood sugar test is used to measure the amount of glucose in blood. The alternative names for this test are fasting blood sugar, fasting blood glucose or fasting plasma glucose test. Glucose a monosaccharide (simple sugar, which is responsible for fulfilling most of the energy requirements of the body. The hormone insulin secreted by pancreas helps regulate glucose levels in the body by transporting glucose into cells. However, certain medical conditions may lead to an increment or reduction in blood glucose levels. Raised blood sugar due to diabetes can lead to complications, such as kidney failure and heart disease and eye diseases whereas low glucose in the blood can cause brain damage if not treated on time.

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  1. Why is a Blood Sugar (glucose) test performed?
  2. How do you prepare for a Blood Sugar (glucose) test?
  3. How is a Blood Sugar (glucose) test performed?
  4. Blood Sugar (glucose) test results and normal range
  5. ब्लड शुगर (ग्लूकोज) टेस्ट के बाद - After Blood Sugar (Glucose) Test in Hindi
  6. ब्लड ग्लूकोज (शुगर) टेस्ट के क्या जोखिम होते हैं - What are the risks of Blood Glucose (Sugar) Test in Hindi
  7. ब्लड शुगर (ग्लूकोज) टेस्ट के परिणाम का क्या मतलब होता है - What do the results of Blood Sugar (Glucose) Test mean in Hindi
  8. ब्लड शुगर (ग्लूकोज) टेस्ट कब करवाना चाहिए - When to get tested with Blood Sugar (Glucose) Test in Hindi

A  glucose test is recommended if the person exhibits symptoms suggestive of high or low blood sugar levels. High glucose levels could be due to:

Symptoms of low glucose in the blood are

There are certain risk factors that can increase the chances of diabetes:

During pregnancy, a blood glucose test is commonly advised between the 24th and 28th week to check for gestational diabetes. Gestational diabetes occurs only during pregnancy, and blood glucose levels usually return to normal after childbirth.

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You will be asked to fast for at least 7-8 hours before the test. If a post-lunch sample is needed, you should eat a light lunch and return to the laboratory after 2 hours for providing another blood sample.

For determining gestational diabetes, women will be given a sugary drink an hour before the test. No fasting is necessary. If reports show higher glucose levels, another test with fasting is needed. If you are on any medications, inform the doctor before discontinuing them.

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A blood sample is drawn from a vein in the arm using a small needle after swabbing the concerned area with an appropriate antiseptic. Some people may feel a slight sting during needle insertion, which will disappear immediately. No other risks are involved during this test. Individuals who have a blood glucose test kit at home can perform the following steps:

  1. Wash hands thoroughly dab them dry with a towel and insert the test strip into the glucometer.
  2. Use the lancing device (provided in the kit) on a fingertip to get a drop of blood.
  3. Touch and hold the edge of the test strip into the drop of blood.

The screen on the device will provide glucose reading immediately.

Use your thumb to avoid sore spots on the pricking site. Results among glucometers vary; hence, the user manual instructions for test inferences should be referred; talk to your healthcare provider in case of any discrepancies.

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Blood glucose levels are individualised based on the following parameters:

  • Duration of diabetes
  • Age and life expectancy of the person
  • Comorbid conditions such as blood pressure and thyroid
  • Known cases of cardiovascular disease or other heart conditions
  • Lack of awareness about blood glucose levels
  • Other patient considerations

Normal results: Fasting (before a meal) or preprandial blood glucose levels are considered normal between 80 and 130 milligrams/deciliter (mg/dL). Post-lunch (1-2 hours after a meal) glucose levels should be below 180 mg/dL.

Abnormal results: Blood glucose levels in higher or lower than the standard range are considered to be abnormal. High blood sugar levels could be due to:

Low blood glucose levels could be due to

Note that blood sugar levels may also fluctuate with strong feelings and emotions or stress. It is important to keep track of every sugar test to understand whether food, activity or emotions affect glucose levels. This will help evaluate if the diabetes plan is effective. If blood sugar levels are repeatedly abnormal, you must speak with your healthcare provider or diabetes educator.

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational perspective and is in no way a substitute for medical advice from a qualified doctor.

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  1. National Institute of Diabetes and Digestive and Kidney Diseases [internet]: US Department of Health and Human Services; Diabetes Tests & Diagnosis
  2. MedlinePlus Medical Encyclopedia: US National Library of Medicine; Blood sugar test
  3. American Pregnancy Association: Glucose Tolerance Test
  4. American Diabetes Association. http://care.diabetesjournals.org/content/37/Supplement_1/S14.full.pdf+html. Diabetes Care.
  5. Virginia A. Moyer, MD, MPH; on behalf of the U.S. Preventive Services Task Force. Screening for Gestational Diabetes Mellitus: U.S. Preventive Services Task Force Recommendation Statement . Ann Intern Med. 2014;160(6):414-420.
  6. American Diabetes Association. Diagnosing Diabetes and Learning About Prediabetes. Diabetes basics. diagnosis.
  7. American Diabetes Association [internet]; Checking Your Blood Glucose
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