blood analysis

Test strips for measuring blood glucose

Introduction

The test strips are used in blood glucose monitoring, proving to be particularly useful for home self-control and possible adjustment of drug therapy under the guidance of the attending physician. In the course of the article we will analyze the advantages, the correct methods of use and the reliability of the test strips and the values ​​provided by the meter.

Usefulness of test strips

Using the test strips in combination with the appropriate meter, called the glucometer, the self-sufficient patient is able to check his own blood sugar values ​​in complete autonomy and in real time, adjusting the drug therapy as necessary according to the doctor's prescription. All this allows to avoid episodes of hypoglycemia or hyperglycemia, frequent in diabetics forced to follow an insulin therapy.

Self-monitoring of glycaemia by test strips and glucometer also has an educational advantage, since the patient, by becoming familiar with the instrument and with normal blood glucose values, can directly test the influence of dietary and behavioral habits (physical activity ) on their own glycemic values, but also the effects of common and transient diseases (such as influenza) on blood sugar.

Overall, therefore, glycemic self-control in a collaborating patient prevents or at least significantly reduces the appearance of typical diabetes complications.

Principle of operation and correct use

The test strips are typically used in association with a special portable detector, called a glucometer. To measure blood sugar is sufficient:

  1. wash your hands with soap and water, and dry them thoroughly
  2. take a test strip from the container and close it immediately
  3. insert the test strip in the meter and wait for the instrument to confirm
  4. gently place a drop of capillary blood on the reactive part (free end) of the strip; the drop of blood is taken through special lancing devices by performing a puncture on a fingertip (before performing the puncture always remember to wash and dry your hands, disinfecting the fingertip). To encourage blood supply and blood flow, it is advisable to gently massage the fingertip before drawing
  5. Wait for the confirmation of the adequacy of the sample (which may be insufficient or excessive) on the part of the meter and read the measured blood glucose value on the display
  6. Record the glycemic value in your diary and adjust the therapy as required by your doctor if necessary. Many glucometers allow you to store the values ​​of several tens of glycemic measurements in the internal memory of the device, and transfer them to your computer via a USB cable; still, some models translate these values ​​into graphs showing for example the average daily blood sugar and the amplitude of daily glucose excursions.
  7. PLEASE NOTE: always use a new, sterile lancing device and a new test strip for each glucose test (the pointers and strips for the glucose meter are disposable)

Since this is a general description, and since various automated devices are available on the market, it is recommended that the procedural standards suggested by the manufacturer be carefully observed. The pharmacist or doctor who is treating the patient should also instruct him on the correct methods of use, dispelling any doubts that may arise.

In general, self-monitoring by test strips is recommended three or four times a day according to the scheme prescribed by the doctor.

In addition to the aforementioned models there are test strips that vary in color in relation to the concentrations of glucose present in the urine with which they come into contact; they are useful, in particular, to testify to the presence of glucosuria, since in normal conditions in the urine there are no significant quantities of glucose.

Accuracy of results

If carried out in full compliance with the rules of correct use dictated by the manufacturer, the measurement of blood glucose through test strips and portable glucometer is particularly accurate. The technological advances of recent years have in fact made it possible to significantly increase the reliability of the measure, even in particular conditions. Among these, the value of hematocrit, which when particularly low (60-65%) could - depending on the model - make the estimate of the concentration of glucose in the blood inaccurate (over-or underestimating it by approximately 10-15%). The same goes for extremely high or extremely low blood sugar levels.

Even the operating temperature is important, an environment that is too cold (40 ° C) could alter the accuracy of the glucose values ​​returned by the appliance; the same applies to the values ​​of altitude and ambient humidity.

Finally, there may be important differences depending on the type of test strips used, even if produced by the same company and of the same model (possible variation from lot to lot). For this purpose, some glucometers require to insert the code or chip present in the package to self-calibrate based on the characteristics of the test strips used; others are able to detect this data independently. In the event of an automatic procedure (chip insertion or automatic detection) it is however important to make sure that the meter displays the same code shown on the strip packaging. All these calibration operations must be repeated when opening and using a new package of test strips.

Beyond the specific accuracy of the test strips and glucometer used by the patient, it is in any case recommended that self-monitoring be periodically integrated with the analysis of traditional plasma glucose using a hospital sample; in this way it is possible to compare the data and make sure that the glucometer works correctly (for this purpose, carry out the two measurements at the same time and in the state of nutrition, or better yet, self-monitor the blood sugar with a glucometer and test strips immediately before or immediately after the hospital withdrawal ).