What are blood glucose meters?
Self monitoring of blood glucose (SMBG) is an important part of day-to-day diabetes management. Blood glucose meters are small, hand-held battery operated machines. They quantify the glucose level by processing a small drop of blood on a strip, which is inserted into the meter. The blood glucose value is shown as a number on the screen.
Although blood glucose meters are generally very reliable, they are not perfect. The technology used in blood glucose meters is not as accurate as testing done in a hospital lab and we know that there is some variability between meters and between tests.
MARD (Mean Average Relative Difference) is the standard measurement of accuracy of blood glucose meters comparing them to venous blood using a laboratory measurement.
The International Standardisation Organisation (or ISO) guidelines for blood glucose meters are a detailed set of standards which blood glucose meters should meet. In 2013, these quality standards were revised to provide stricter accuracy criteria. Blood glucose monitor manufacturers had to ensure that their blood glucose meters met these standards by the end of May 2016.
The new accuracy standards (ISO: 15197:2013) require the following minimum criteria:
- 95% of results must fall within 15% of laboratory results at concentrations of 5.5mmol/L or more.
- 95% of results must fall within +/- 0.83mmol/L of laboratory results at concentrations of less than 5.5mmol/L.
You can reduce your meter variability by thinking about the following.
| Factors that affect accuracy | Solutions |
|---|---|
| Test strip problems | Throw out damaged or outdated test strips. Store strips in their original packaging and keep them away from heat. Replace the bottle cap promptly after removing a test strip, to protect them from moisture and humidity. |
| Altitude & extreme temperatures | Keep your glucose meter and test strips at room temperature. Check your meter manual for more information. |
| Alcohol, dirt or other substances on your skin | Wash your hands and the testing site with soap and water (or use a neutral hand wipe) and ensure they are dry before pricking your skin. |
| Improper coding |
Some meters must be coded to each container of test strips. Be sure the code number in the device matches the code number on the test strip container. |
| Not enough blood applied to the test strip | Apply a generous drop of blood to the test strip. Don't add more blood to the test strip after the first drop is applied. Most meters use capillary draw technique so you can see enough blood is used. |
| Testing site location | If you think your reading is wrong, test again using blood from a different finger. |
| Interfering substances |
Ascorbic acid (Vitamin C), Paracetamol (Calpol) and xylose may interfere with glucose testing. Check the instructions to find out what substances may affect your meter. |
There are many meters on the market. The team at UCLH recommend that you use either a meter that has been recommended by North London Guidance (Gluco Fix Tech that tests both blood and ketones) or a meter that communicates with your insulin pump (Accu-Chek Guide link meter with 780G insulin pump).
You do not have to pay for a meter. The diabetes nurses will be able to supply you with one meter and advise you how to obtain a spare (in case you meter stops working or to use at school).
You can get more meter strips from your GP on a repeat prescription. Each different type of strips have a unique PIP code which enables your GP to prescribe the correct strip for your meter. This information will be in the box with your new meter or the diabetes nurses can give you a written prescription details.
All the blood glucose meter companies produce ‘control solutions’ that can be used to test your meter. To test your meter, use a drop of the liquid control solution, just like you would test a drop of your blood. The value you get should match the value written on the test strip container label. We recommend that you test you meter at least once a month.
To facilitate the monitoring and review of blood glucose levels, ensure that the meter is set with the correct time and date. Follow manufacturer’s instructions on how to change the time and date if necessary. The time should be updated whenever the clocks go back or forward.
Most of the meter companies have a customer care line. If you register here, you can get free batteries and control solution directly from the company. They should also be your first port of call should your meter stop working and will normally send you a replacement meter.
Emergency mobile: 07940 476811
Email: uclh.
Further information and fact sheets can be found on our Children and Young People’s Diabetes web page.
Page last updated: 17 January 2025
Review due: 01 January 2027