“Glucometers are invaluable when frequent testing is required like pregnancy induced diabetes, type 1 Diabetes and insulin treated type 2 diabetes mellitus. Testing and tracking sugars helps the doctor customise treatment to best suit the unique needs of the individual patient”, according to Dr Tejal Lathia, Consultant Endocrinologist, Fortis and Apollo Hospitals, Navi Mumbai.
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. If you are wondering what other types of blood there is, we’ll explain that in just a bit.
When your blood is tested in a laboratory, it uses blood withdrawn from the veins.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.
Other factors also influence the measurement by glucometers: environmental conditions (temperature of the room, altitude), depth of the finger prick, whether the first or second drop of blood was taken, hematocrit (i.e. the percentage of red blood cells in the blood), interstrip variance, etc.
Laboratory glucose testing is done on plasma (thus without the influence of hematocrit) and under more controlled conditions. This means that laboratory results are more accurate than your glucometer’s readings. The difference can be higher or lower than your actual values. But you don’t have to worry about this.
The International Standardization Organization (ISO) prepared recommendations that glucometers be made in such a way that they have to be within 10% of the laboratory values for values <100 mg/dl and within 20% for values >100 mg/dl. This means that the margin of error has been accounted for already.
The purpose of a glucometer is to encourage self-monitoring of blood glucose. A reading is often supposed to be compared with the previous reading(s) so that you can track the trend. A glucometer is more than equipped to fulfil this purpose. That’s what really matters.
These facts mean that you should not worry too much about the differences in the readings. Be aware of your previous reading and your diet. Of course, when your readings are too high or too low or differ too much from the previous day, you should take another reading. If it is still the same, contact a doctor or get a laboratory test done to confirm it.
Glucometers are cheaper than laboratory testing, more convenient, allow much more frequent testing. Also, the results are obtained instantly, whereas it can take hours in a laboratory test. And perhaps most importantly, glucometers give people with diabetes or prediabetes a chance to take control of their condition based on these results.