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Fasting blood sugar
Dear doctors,
I recently tested positive for diabetes with 309mg of fasting blood sugar. Doctor prescribed medicine and doing walking physical activities for last one month. Today when i checked fasting blood sugar using one touch glucometer it has given 152mg. Immediately i went to lab and tested and the result showing 102mg dl and post meal showing 164 without taking medicine.
I m confused now which one to trust. Glucometer or lab result.. why so much difference between glucometer and lab within 15mins time. Please suggest
Answers (15)
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Take your glucometer along with you in lab
Give sample
Immediately take glucometer reading
Then analyse
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Taking the blood and testing in lab is more accurate
Glucometer results are variable
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Better always test in lab to show to your doctor to adjust the dosage
Glucometer results for just reference
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Hello
You’ve asked an excellent and very practical question — this difference between glucometer and lab readings is something many diabetics notice.
Here’s what’s happening:
Glucometers use capillary (finger-prick) blood, while labs use venous blood samples — so mild variations (up to 15–20%) are normal.
Glucometer accuracy can be affected by strip quality, storage, calibration, hand cleanliness, and timing.
Lab results are more reliable for diagnosis and monitoring major changes, while glucometers are best for daily trend tracking.
In your case, a lab fasting sugar of 102 mg/dl and post-meal 164 mg/dl (without medicine) shows good improvement — your body is responding very well to lifestyle changes
But since your initial sugar was high (309 mg/dl), we should confirm whether your pancreas is recovering fully or if you’ll still need a small maintenance dose of medication. I can help you interpret your complete sugar trend, review your reports, and make a safe plan to prevent future spikes naturally.
You can message me directly on WhatsApp at nine three two six zero two zero five three six for a private one-on-one consultation. I’ll guide you step-by-step on how to stabilize your sugar levels permanently and avoid medicine dependency. 🌿
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Dear brother, though the diagnostic procedures are scientific, the values you get should not set you in panic mode. Because its not important for anyone to be over concerned.
Its a Lifestyle disorder and so balancing the Lifestyle should be enough to set you back in to a normal healthy person.
Hence do focus on finding the problems that led you to this state snd correct it. Take a lifestyle assessment test here at www.cellabrity.ae
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Lab tests are more reliable than household glucometer
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get HbA1c done as it will give your glucose levels of last 2 months .
if HbA1c <7 continue the same lifestyle
and medication
if it is 7.5 or above consult doctor and get your medication changed
Health Tips
exercise 4-5 days a week minimum 45 mints ,
good diet with all daily requirements .
regular medication
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This difference is quite common and usually happens due to variation in how samples are collected and measured.
Glucometers use a small drop of capillary blood from the finger, while labs use venous blood, which tends to show slightly lower readings. Also, factors like unclean hands, delay in testing after pricking, expired strips, or improper calibration can cause errors in glucometer readings.
Since your lab fasting sugar is 102 mg/dl and post-meal 164 mg/dl without medicine, that suggests a good improvement with your current diet and exercise. Continue your healthy habits and repeat the test after a week at the same lab for consistency.
You are doing very well; ensure you check your sugars at the same time and same method for reliable trends. For clarity and proper management, an online consultation will help.
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First of all, Values differ when we check blood sugar using glucometer and get it checked by laboratory. A laboratory value is more reliable than glucometer. Around 10-15% variation can occur in glucose value when we measure it by glucometer and laboratory. But some glucometer can give more fluctuations. Apart from this, blood sugar is also affected by various factors one is exercise. So when you rushed to lab, you must have done some physical work.
Another factor is time from sample collection to process it. Sometime lab technician keep samle for quitelong and then processe it that lead to lower glucose value.
So don't worry, rely on laboratory value. Which is under controlled.
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Hi.
With your fasting that high (309), clearly you have diabetes.
Now in the morning you took the medicine and checked your blood sugar which has come quite under control. Note that machine readings can vary so much so that if u may have taken another reading from your glucometer at that very instance, the reading would've possibly been a little plus or minus from 152.
To add this, lab tests the blood sample from a vein, whereas glucometer measures from capillaries. So its an accepted difference, and has less effect on decision making for which anti-diabetic drug to use.
Regarding which is better of the two, it depends on ease or repeat samples rather than lab accuracy.
Evidently, rapid glucose samples are more easy and safer compared to multiple daily vein pricks for charting blood sugar.
Next Steps
For all practical purposes, continue keeping a Glucometer measures blood sugar chart, and eventually once in 15-20 days u may get your Fasting and/or Random blood sugar measured at the Lab.
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Check out blood sugar levels at fasting and 2 hours after Breakfast Lunch and dinner for 5 days and see if the sugar levels are in range or not
Then discuss with the reading
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The glucometer looks at capillary blood glucose. The lab looks at venous blood glucose.. both are reliable. A variation of around 40-50 is present.
Q.1- Did you actually go to the lab within 15 minutes.
Q. 2- Why? Use the glucometer and be content. The next thing might be testing from 3 labs and then from a lab in another country?
Use one method
Stary exercising
Avoid tobacco and alcohol
Take your meds
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Hi some variation in lab and glucometer values are expected but the difference depends on the type and standard of gucometer , the proper storage of glucosticks, the pricking method, the presence of any contamination on skin etc kindly follow up with lab values atleast monthly once.
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Dr. A Raja Prasanna Kumar
Pulmonologist
46 yrs exp
Hyderabad
Lab is good. Pl continue the Diet, exercise , and life style changes. It appears, you are well motivated. Pl consult.
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Dr. Anuj Mothsra
General Physician
6 yrs exp
Jhunjhunu
Can help you, kindly consult and provide detailed history for proper diagnosis and further management
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Dr. Marini Vanitha
Diabetologist
12 yrs exp
Kakinada
Lab is reliable.
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