Determination of blood sugar is one of the most common tests for diabetes performed by modern clinical diagnostic laboratories. Today, a blood test for diabetes can be done not only by laboratory methods, but also with the help of various portable devices that are based on the principle of “dry chemistry”. These devices, called blood glucose meters, allow you to measure your blood glucose at home. Currently in our country such glucometers as iChek, OneTachSelektSimple, Clover Check , etc. have become widespread . The choice of such a device in each individual case depends on many subjective and objective factors. In this article, we will tell you what types of blood glucose meters exist, what is their difference, and how to choose a blood glucose meter .
Reflectometers
Modern systems for measuring sugar with a reflective method are easy to use and compact. They need minimal user involvement to minimize subjective errors. Thanks to the use of “indelible” technology, by placing the color analyzer under the test strip, there is no need to erase red blood cells. Modern glucometers of this type are equipped with an automatic time counting, they can warn users about possible errors in the process of measuring glycemia. In addition, to determine blood sugar with such devices , only up to 1-2 μl of blood are needed.
Biosensors
Biosensors are devices that measure the electrical signal produced by a chemical reaction. These meters use test strips with a touch electrode and sensor. The sensory electrode contains an enzyme that accelerates the breakdown of glucose, and a mediator that participates in the redox reaction.
In biosensors, a drop of blood must be applied to the electrode outside the device and at the same time it does not come into contact with the internal component of the sensors. In order to answer the question: “How to choose the right blood glucose meter”, you need to take into account the following factors:
- the frequency of use of the meter by the patient;
- ease of use;
- the cost of the device and test strips;
- type of batteries and ease of replacement;
- the size of the device and the display;
- availability of memory;
- availability of warranty service.
When deciding which meter to buy , patients should also pay attention to the factors described below.
Blood volume
In modern blood glucose meters, the volume of blood required for the correct determination of glycemia is 2 μl. Diabetic patients should be aware that some blood glucose meters may show underestimated readings if the blood drop is too small. Additional application of a drop of blood to the test field in case of insufficient first sample will also give an incorrect result. It is important to remember that if an inadequate drop of blood is applied to the test strip, you must re-measure using a new test strip and apply a large drop of blood to it. However, many patients are reluctant to repeat measurements using a new test strip, which leads to incorrect results and, as a result, to incorrect treatment tactics.
Shelf life and storage of test strips
The test strips are stored individually or in a special tube, which usually contains a silica gel (desiccant) to prevent excess moisture from affecting the reagent. Test strips must be stored at a specific temperature without being exposed to excessive cold or heat. Therefore, the test strip container must be closed immediately after use. This will prevent damage to the remaining test strips. Typically, strips have a shelf life of about 2 years, but improper storage will degrade the reagent faster. It is also important to remember that the shelf life of the test strips after opening the tube is no more than 3-4 months. It is not permissible to use test strips with an expired expiration date, as this may cause incorrect blood glucose measurements.
Influence of hematocrit
When blood plasma interacts with the dry reagent of the test strip, the dry chemical agents dissolve, as a result of which a reaction is triggered. This process is influenced by hematocrit when using whole blood. Blood samples with increased viscosity or high hematocrit can affect the amount of plasma absorbed, the rate, and also interfere with the diffusion of glucose. This in turn causes falsely low blood glucose levels. Well, a sample with a low hematocrit, respectively, will give falsely high blood sugar values.
Restriction on use
It is very important that the procedure for applying a blood sample to the test strip is correct for each measurement. Therefore, blood glucose meters designed for use with whole blood are not suitable for certain types of patients. Such devices cannot be used by people with hyperosmolar hyperglycemia, since their blood sugar levels can be significantly lower than the true indicators of glycemia. When deciding which meter to buy , it is important to take into account the effect of certain drugs and other substances that are indicated by the manufacturer, which can, in one way or another, affect the interpretation of the measurement results. Biosensory or reflective blood glucose meters that use the glucose oxidase method to measure blood glucose are susceptible to blood bilirubin or high lipid levels, vitamin C, paracetamol, or uric acid.
Calibrating the instrument
Modern blood glucose meters are calibrated by the manufacturer, but users also need to know how each package of test strips or electrodes is calibrated. As a rule, code changes are made to the program manually using a special code button on the meter. Calibration is known to have a significant effect on blood sugar measurement results. In order to minimize the probability of operator error when manually changing the code, manufacturers use the following tools:
- information about the code is placed directly into the test strip for the meter to read it on its own;
- each batch of test strips is assigned a calibration key that is inserted into the meter;
- Each batch of test strips is equipped with calibration strips to transfer the necessary information to the meter.
When choosing a meter, it is important to know that blood glucose readings will differ from those measured with a plasma calibrated meter.
Well, in conclusion, I would like to remind you that a device for individual use, first of all, should be easy to use. To minimize the likelihood of incorrect blood glucose measurements, the patient should know how to use the meter.