Why is the difference between Glucometer and lab test of blood glucose (sugar)?

For every diabetic patient, one major question is which blood sugar reading is accurate or authentic? The one he or she gets at home on Glucometer (Self-Monitoring Blood Glucose Devices) or the report done at a pathology lab. The answer is not straight forward but one can trust the lab report more than the glucometer reading at any given time.

On the occasion of World Diabetes Day (14th November), we, decided to spread awareness about correct blood glucose readings and recommended practices to perform this common test.

To understand the difference in reading, we must understand how each test are conducted.

How glucometer works to detect blood glucose level?

It is a device used to instantly measure blood glucose, generally using a drop of blood from a finger prick. It measures glucose using the whole blood in your capillaries.

What type of blood is used to test blood glucose in pathology lab?

When your blood is tested in a laboratory, it uses blood withdrawn from the veins. Here, they measure the amount of glucose in the plasma. This is the part of the blood left after taking out the blood cells. Thus, the two methods measure different parts of the blood, which leads to differences in the glucose values reported.

Which factors affect measurement of blood glucose on glucometer?

Environmental parameters (room temperature, altitude), the depth of the finger prick, whether the first or second drop of blood was drawn, the hematocrit (i.e., the proportion of red blood cells in the blood), interstrip variation, etc., all affect the measurement by glucometers.

Are glucometers accurate to check blood glucose level as compared to pathology lab report?

Plasma is used for laboratory glucose testing, which eliminates the impact of hematocrit and allows for more precise results. This implies that laboratory findings are more reliable than the results of your glucometer. Your real values may be higher or lower than the difference.

How much is glucometer accurate?

The International Standardization Organization (ISO) put out guidelines that glucometers be constructed so that, for readings below 100 mg/dl and over 100 mg/dl, they must be within 10% and 20%, respectively, of the laboratory values. This indicates that the error margin has already been taken into account.

When to use glucometer then it is not accurate as compared to pathology lab?

Glucometer is handy when there is emergency particularly in cases of fainting spells, diabetic coma and in cases where frequent blood glucose monitoring is required such as pregnancy with diabetes history.

How to calibrate glucometer with your pathology lab reading?

  • Take the glucometer to the laboratory
  • Give the blood sample for the glucose measurement in the laboratory
  • Immediately check the blood glucose with the glucometer using capillary blood after finger prick.
  • If the glucometer glucose values are within 15-20% of the laboratory glucose values, then the glucometer values are accurate and can be used for regular monitoring of blood glucose.

What is the cost of blood glucose (sugar) test in Pune?

At Pro diagnostics, we provide blood sugar test at just ₹50. We also provide home sample collection services in Pune. To contact, click here.

What is the cost of hba1c test in Pune?

At Pro diagnostics, we provide hba1c test at just ₹400. We provide online blood reports via WhatsApp.

What is the special diabetes package at Pro Diagnostics?

On the occasion of World diabetes day (14th November), we are providing special diabetes package of blood tests including Blood sugar, hba1c test, creatinine and cholesterol at just ₹500 (MRP ₹850).


Even though glucometer may meet certain criterions of accuracy, the devices themselves do indeed have certain inherent significant errors which can cause wrong medication and/or treatment that could be dangerous, particularly in the use of glucometer devices in the home where most testing is performed. So its always better to trust your pathology lab reports than glucometer reading.

About Author -

Dr. Chaitrangi Paranjape, MD Pathology, she is the owner and chief pathologist at PRO diagnostics , Pune. She has more than 10 years of experience and she has worked with many renowned diagnostic centers and medical institutes including Metropolis, Nucleus, Pioneer, Sunrise diagnostics, Bharti Vidyapeeth Medical college, Pravara Institute of Medical Sciences. Currently she is also working at Institute of Infectious Diseases.

Why choose us:

At Pro diagnostics, with the use of modern technology, experienced phlebotomists and technicians, quick, accurate reports are provided. At PRO diagnostics, all types of pathology tests of blood, urine, sputum are provided at best rates. Home sample collection facility is also available. Reports are provided on mobile via email or WhatsApp.

To book your tests, call at +91-9856620620 (Home Collection) or logon to www.prodiagnosticsindia.com

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Frequently Asked Questions

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Dr. Chaitrangi Paranjape, is the chief consultant pathologist at Pro Diagnostics Pathology Lab Pune. She has more than 10+ years of experience in pathology.

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