Blood Glucose Monitoring: Ensuring Accuracy in Diabetes Management

Monitoring blood glucose levels is a crucial part of diabetes treatment. However, many patients encounter inconsistencies in blood glucose readings when using different brands or even different models of the same brand. This often raises concerns about the accuracy of glucose meters. Today, we will explore how to properly evaluate the accuracy of a blood glucose meter.

1. What to Compare?

The gold standard for blood glucose measurement is the venous blood glucose test conducted in hospitals. Diabetes diagnosis is based on plasma glucose levels. Therefore, all blood glucose meters are compared against the results from biochemical analyzers, not against other meters. The best way to verify your meter’s accuracy is to compare its readings with your fasting venous blood glucose results from a hospital. After blood is drawn by a nurse, immediately test yourCapillary Blood Glucosewith your meter, ensuring the same timing. Once the hospital results are available, compare the deviation.

It is essential to understand that blood glucose levels fluctuate:

• Different Blood Samples:Blood glucose levels vary between venous and capillary blood.
• Different Times:Blood glucose levels change throughout the day.

Therefore, discrepancies are acceptable as long as they fall within a reasonable range.

2. What Is an Acceptable Error Range for Blood Glucose Meters?

① Accuracy

According to the international standard ISO 15197, the error range for blood glucose meters is as follows:

• For blood glucose levels
• For blood glucose levels ≥5.6 mmol/L, the deviation should be within ±15%.

This means that if your venous blood glucose is below 5.6 mmol/L, your meter reading should fall within ±0.83 mmol/L of that value. For venous blood glucose levels above 5.6 mmol/L, the meter’s deviation should not exceed ±15%.

② Repeatability

Even when using the same blood sample, repeated tests may yield slightly different results. According to international standards:

• For blood glucose levels
• For blood glucose levels ≥5.6 mmol/L, the coefficient of variation (CV) should be

3. Factors Influencing Test Results

① Hematocrit (HCT) Levels

Peripheral blood glucose tests measure whole blood glucose, which is influenced by red blood cell counts. Higher hematocrit levels can skew results. VenousBlood Tests measure plasma glucose, which is less affected by HCT levels.

② Excessive Pressure or Improper Sampling

Peripheral blood samples are whole blood and can be affected by skin moisture, alcohol residue, and puncture depth. Excessive pressure during sampling can cause tissue fluid to mix with the sample, affecting the results. Different sampling sites can also yield different readings, with studies showing that glucose levels from the ring finger are closer to venous blood glucose.

③ Test Strips

Glucose meters work by detecting the electrical current generated by the reaction between glucose and chemicals on the test strip. The enzyme activity on the strip can impact accuracy. Therefore, strips should be stored in a dry environment and used within their expiration date, preferably at temperatures between 18°C and 35°C.

Other factors, such as certain diseases, can also interfere with results. For instance, changes in blood viscosity due to conditions like diabetic hyperosmolar coma, abnormal hematocrit levels, or hyperlipidemia can affect the absorption process on test strips. The difference between capillary and venous blood glucose is minimal when fasting but can vary post-meal due to glucose absorption by tissues. Handwashing practices before sampling also impact results.

4. How to Improve Measurement Accuracy?

• Choose the Right Meter:Opt for reputable brands that offer HCT correction and temperature correction features.
• Select the Correct Sampling Site:Use the ring finger and ensure proper cleaning and disinfection. Allow alcohol to evaporate before sampling.
• Ensure Proper Blood Volume:Use the correct lancet setting for adequate blood flow. Discard the first drop of blood and use the second drop for testing to avoid contamination.
• Store Test Strips Properly:Keep strips in a cool, dry place between 2°C and 30°C. Ensure they are stored in their original container, and avoid using expired strips.

It is normal to experience some fluctuations in readings. However, as long as they are within the acceptable range, there is no cause for concern. Avoid using multiple meters simultaneously, as this may lead to confusion. Instead, choose one reliable meter with good after-sales support for long-term monitoring. Track blood glucose trends and consult a doctor if there are significant fluctuations.

5. What About Laser Glucose Meters?

Laser glucose meters use a different sampling method, but their accuracy still depends on the quality of the test strips. In fact, laser meters can be more accurate because they help purify the skin and remove impurities before sampling.