Different results with glucose measurements?

We regularly receive questions about a difference in glucose measurements. A glucose meter can give a different result at 10 o'clock in the morning than at 6 o'clock in the evening. Two glucose meters next to each other will also have an error. In principle this is no problem at all. Even if you were to measure the same drop of blood on two meters at the same time, you might find an deviation. The meters are then not suddenly unreliable. But what exactly is this?

Deviation in glucose meters

Every glucose meter has a deviation (spread), with most meters this is a maximum of 15 percent of a reference value. This 15 percent is described in the glucose meter consensus document, which serves as a quality reference in the Netherlands. This describes what requirements a glucose meter must meet in order to be reimbursed by insurers (ISO standard). All meters that you find on diabetesmagazijn.nl comply with this ISO standard. They therefore never deviate more than 15 percent from the reference value.

For low glucose values ​​(glucose < 5,55 mmol/L), the deviation is calculated in absolute numbers: the absolute deviation may not be greater than 0,83 mmol/L.

As the results of two blood glucose meters are compared with each other, the above standards do not apply, because you do not know what the reference value is.

Compare glucose meters

If you want to compare glucose measurements, you should only do so with laboratory tests. If you compare two glucose meters with each other, they can both differ and you still do not know which one differs and by how much. Optimal is when compared with a well-defined reference method. In practice, laboratory research suffices.

Suppose the reference value (a value measured in the laboratory, in the same sample, at the same time) turns out to have a value of 10 mmol, then a glucose meter may indicate a value between 8,5 mmol and 11,5 mmol and then it is still correct.

The meter meets the ISO standard with the above calculation example and is therefore reliable. Before treatment, it is of the utmost importance to always check the insulin setting of people with diabetes with the same meter. And the advice is also to look at averages or repeat measurements, so not to immediately draw conclusions based on one measurement.

Differences in measurements occur. But this is almost never due to the meter. The causes can be sought, for example, in different moments of measurement or strips that have been exposed to moisture or light. If you are in doubt, you can try to take measurements with control solution, but it is best to compare the measurement with laboratory research.