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Diabetes India
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is there any difference in glucose in venous and capillary blood ?

We test blood sugar at home using a glucometer . The blood is collected through a finger prick.This blood comes from a capillary,and whole blood is used to measure glucose. Whereas in a lab. blood is collected from a vein and glucose estimation is done using serum.

So there is difference in source of blood as well as samples to be tested.

Will it affect the diagnosis and/ or management of diabetes ?

7 Replies

To my knowledge,the results differ,The serum readings will be slightly higher by about 10 points.It is generally advised that glucometer readings may not be used for clinical purposes.Also,to be sure,both methods can be used at the same time once in a while to calibrate the glucometer according to the lab results.


There is small but significant difference in the blood glucose results analysed on a bedside glucometer when the samples are taken from capillary or venous sources. Caution must be exercised in accepting the results as equivalent or using either as substitute for a laboratory blood glucose results.



Even at that time glucometers were plasma adjusted,so there is no confusion about that.

It is also almost universally accepted that there is no variation in basal or fasting blood sugar, whether blood is from capillary or a vein. It is only in post meal that there is some difference in blood sugar reading . The whole blood from capillary shows higher bs reading by approx. 10% than the bs estimated from plasma,(lab. Test using blood from a vein ).

The reason is easy to explain,if there is need.


Dear Indiacratus, the para in reference was published in 2005.


Thank you.


The blood sugar from capillaries and veins does not matter when taken for the management of blood sugar.Difference of 10 to 20 percent does not matter.Secondly,the range of FBS and PP ranges are arbitrarily fixed,which were different from time to time. The international range was first fixed at 135 mg/dl which has changed from time to time and now it is below 100 mg/dl.This way it has been estimated that nearly 60% Indian population suffers with diabetes. All is arranged by pharmaceutical companies to sell their products.This causes depression and the level increases.So my advice is take it lightly till there is level beyond 200 mg/dl

1 like

Precisely said without any room for doubts. Well.


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