Self Monitoring of Blood Glucose


Regular monitoring of blood glucose provides a good overview about metabolic condition. An intensive control of the measured values allows an evaluation if blood glucose levels have become worse. If this is the case the patient can quickly get in contact with his physician to get advice how to optimize the treatment. This can help to prevent metabolic decompensation and diabetic late complications. Self monitoring of blood glucose is extremely important for insulin-dependent diabetics as they calculate the dose of insulin on glucose levels. It is also very important to document the measured glucose results in a special diary to show it to the physician. Daily averages give an idea of the actual HbA1c and the quality of diabetes therapy.

 

Why Self Monitoring of Blood Glucose?

  • Protection against hypoglycemia and hyperglycemic decompensation
  • Better understanding and better control of your diabetes
  • Higher quality of life level with more safety during leisure time, work, vacation and sports
  • Insight in metabolic processes of the body
  • Information about impact of exercise, hormonal influences and stressy situations on blood glucos
  • Better understanding of therapeutical measures
  • Tighter control and trusty relation with the diabetes care team
  • Self responsibility for treatment
  • Better options in work
  • Smaller number of ill staff and less time spent in hospital
  • Higher expectancy of life through prevention of diabetic late complications

 

When and how often taking a measurement?

The frequency of measuring depends on the kind of therapy. If you are type 2 diabetic on oral and/or insulin therapy or if you administer insulin twice a day during a Conventional Therapy you should consider with your physician and healthcare team all details regarding blood glucose testing. If you perform Intensified Insulin Therapy or you wear an insulin pump the frequency of blood sugar testing should be minimum 6 times a day.
 

  • After getting up / before breakfast
  • Before lunch
  • Before dinner
  • Before going to bed
  • If required 


In special situations the blood sugar should be tested more frequently, e.g. when you suspect hyperglycemia or even ketoacidosis, illnesses with fever, nausea or diarrhoea, intake of new medication or strong interferences of the daily life (night shift, holidays abroad with time delay).

 

Measurement Systems / Calibration

There are two ways to measure the blood sugar depending on the used meter.

Reflector system:
Photometric measurement is based on an enzymatic reaction and consequent colour reaction in the testing zone of the test strip. The intensity of the colour is identified by the meter and is then calculated into a corresponding blood glucose value.

Biosensors:
The main difference between sensors and colour based test strips is that the glucose reaction is linked with a biochemical reaction which leads to an electric signal. This current can be measured and corresponds with an exact blood glucose value.
 
Meters from former generations have to be coded by inserting a chip or by entering a special combination of numbers when opening a new vial of test strips. Most of the recent meters are now based on the new No Code technology.
 
The glucose range that can be measured is between 20 and 600 mg/dl (1.1 – 33.3 mmol/l).

Calibration
Blood glucose meters can be calibrated on whole blood or plasma (please refer to the Instructions for Use of your meter). The absolute majority of meters today available are plasma referenced.

NOTE: plasma referenced meters show 10 – 15% higher values! Do not use contemporarily meters of different manufacturers as the meters could show results which deviate a lot from each other.

 

Correct Handling of Test Strips

The adequate test strip
Every blood glucose meter has its own test strips where the blood sample has to be applied. The main reaction for measuring blood glucose takes place on the test strip.

Storage of the Test Strips

  • Store in dry places (not bathroom).
  • After taking out a test strip from the vial immediatley close it again to avoid entry of humidity.
  • Do not store test strips in the car as temperatures in summer and winter can reach extremes.
  • Check expiration date.
  • If meter has to be coded do not forget to check code on the test strip vial and coding of the meter.


 

Sources of error

Mistakes at measuring your blood glucose can lead to wrong results. There are multiple causes: operating problems with the meter, defective test strips or meters, different interferences.
 
The patient has to be trained to use the meter and the test strips to avoid problems. Using a meter is normally very easy and the training can be done quickly.
 
Tests with control solution from time to time ensure best quality of the blood glucose testing. It makes sense to perform a test with control solution when opening a new vial of test strips, if the meter dropped down or was somehow damaged, if the test results do not reflect your personal feeling or if results are somehow suspect.

Possible sources of error
Most problems are caused by mistakes during operation. Only on rare occasions meter, test strips or other interferences cause problems.

Damaged test strips
Test strips should not be exposed to direct sunlight, extreme humidity, cold or warm temperatures and should not be used after expiration date. These sensible diagnostics have to stored in the original vials, which should be closed immediately after taking out one strip.

Damaged meter
Blood glucose meters are high precision instruments and should be handled after the instructions of the manufacturer. The meter is operated with sufficiently charged batteries. Correct insertion of the test strip has to be checked.

Handling errors
Operation of a new meter has to be trained. The correct sampling of a blood drop should be educated as well:

  • If the finger is pressed too much the blood sample will be diluted with liquids from the tissue which can lead to wrong results.
  • Wash your hands thoroughly to avoid pollution of the blood sample with residues from food and for hygienic reasons.
  • Dry hands thoroughly to avoid dilution of the blood sample with water.
  • Disinfection is not needed.
  • The size of the blood sample has to be sufficient to enable a correct testing at the reaction zone of the test strip.
  • The size of the blood sample has to be sufficient to enable a correct testing at the reaction zone of the test strip.
  • If using a meter which has to be coded do not forget to set the new code when opening a new vial of test strips.
  • Heat, direct sunlight, extrem high humidity in the air (water steam) or extreme cold temperature harm meter and test strips.


Other interferences
Both substances from the body and from outside (medication e.g. vitamin C, Acetyl salicylic acid,..) can influence accuracy of the test results.

Values can deviate to higher or lower results. Please refer to Instruction for Use of your meter and your test strips. Test results can be incaccurate if a person has very high or very low hematocrite levels.
 
After intensive loss of water (strong diarrhoea or nausea) test results can be inaccurate. Residues of disinfecting agents have to completely disappear to avoid inaccurate results. Contact your diabetes health care team for further information.

 

Documentation

As every blood glucose value represents just a snap-shot it is useful to create a daily profile for several results per day. Self monitoring of blood glucose only makes sense if consequences are taken. It is important to write down test results in a diary.

This documentation is the background for the physician and the diabetes team to adjust the diabetes therapy, stores information regarding certain special situations and helps recognizing intra-daily fluctuations. Keep your diary regularely and correctly. If not noted results will be forgotten and are lost for ever.
 

How to keep record:

  • Blood glucose value with date and time
  • Intake of food (BE)
  • Intake of insulin
  • Special situations like sports, hypoglycaemia, stress, diseases, etc

Modern technique assists you in your diabetes therapy. For most of the blood glucose monitoring systems data management systems are available. Special cables help to download data from your blood glucose meter to evaluate in it by means of your PC. With help of a personal computer the diabetes therapy gets even easier. An appropriate software helps to create an accurate documentation about therapy. 

 

 

Blutentnahme
Für die Blutentnahme nutzen die meisten Diabetiker die seitlichen Ränder der Fingerbeeren. Diese sind sehr gut durchblutet, so dass sich leicht ein Blutstropfen daraus gewinnen lässt. Die Mitte der Fingerbeeren sollte ausgespart werden, da diese Stelle durch eine hohe Dichte an Sinnesrezeptoren sehr schmerzempfindlich ist.
 

    Damit das tägliche Stechen von bis zu 10 mal die Finger nicht zu sehr belastet, sollte man folgende Punkte bedenken:

    • Vor der Blutentnahme Hände mit Seife und warmem Wasser waschen und sorgfältig abtrocknen. Neben der Rei­ni­gung fördert dies auch die Blut­zirkulation. Desinfektion ist nicht notwendig – Rückstände des dazu verwendeten Alkohols könnten das Ergebnis verfälschen.  
    • Die seitlichen Ränder der Finger­spitzen punktieren, nicht die Mitte, denn dort sind mehr Nervenzellen als am Rand. Das Nagelbett aussparen, hier könnten sich sonst Ent­zünd­ung­en bilden.  
    • Die Lanzette nach jedem Einstich wechseln, ansonsten stumpft die Nadel zu sehr ab und kann sich auch an der Spitze verbiegen. Das verursacht unnötige Schmerzen oder größere Verletzungen als notwendig. Außerdem steigt die Gefahr von Infektionen und Entzündungen durch das Eindringen von Keimen.  
    • Dünne Lanzetten (es gibt mittlerweile schon welche mit nur 0,2 mm Durchmesser) verwenden, diese verringern den Einstichschmerz und garantieren trotzdem eine genügende Blutmenge. Die Größe des Bluttropfens hängt nicht von der Dicke der Lanzette, sondern von der Einstichtiefe ab. Moderne Blut­zucker­mess­ge­räte brauchen nur mehr extrem geringe Blut­mengen. 
    • Die Finger wechseln - es eignen sich Zeigefinger, Mittel- und Ringfinger. Einige haben auch mit dem kleinen Finger oder dem Daumen keine Probleme.  
    • Wenn möglich: an beiden Händen abwechselnd die Blut­entnahme vornehmen.
    • Die persönlich richtige Stech­tiefe finden: vielleicht muss man gar nicht so tief stechen. Eventuell reicht eine geringere Stechtiefe, wenn Sie das Blut vor der Blutentnahme in den Armen nach unten streichen, die Arme schütteln oder kurz nach unten hängen lassen. Nach dem Stechen sollte nicht gedrückt werden müssen um einen Blutstopfen zu gewinnen! 
    • Die Stechhilfe fest seitlich an die Fingerbeere drücken, dann erst den Auslöser betätigen.

       

    Der richtige Testreifen
    Für jedes Blutzuckermessgerät gibt es eigene Blutzucker-Test­streifen, auf die der Bluts­tropfen aufgetragen wird. Die eigentliche Reaktion zur Bestimmung des Blutzucker­wertes findet auf dem Test­streifen statt.