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How Does a Blood Glucose Meter Work? A Simple Explanation

A blood glucose meter (or glucometer) is a small device that measures the amount of glucose (blood sugar) in the blood. Checking the blood sugar is an important part of managing diabetes. But have you ever wondered how your blood glucose meter actually works?

 

Table of Contents

What Happens When You Test Your Blood Sugar? Arrow icon
Digging Deeper: The Key Role of the Algorithm Arrow icon
Why CONTOUR® Meters Make a Difference Arrow icon
CONTOUR®NEXT GEN: The Most Accurate Meter in the Range Arrow icon

What Happens When You Test Your Blood Sugar?

When you place a drop of blood on a test strip, the strip contains very small, invisible chemical elements that react to the glucose in your blood.

The GDH-FAD enzyme: the star of the strip

CONTOUR® blood glucose meters use an advanced enzyme called GDH-FAD (Glucose Dehydrogenase – Flavin Adenine Dinucleotide). In simple words:

  • When the blood fills the test strip, the enzyme reacts with glucose.
  • It generates a tiny electrical signal.
  • The meter reads the electrical signal and calculates the glucose level.

Why is GDH-FAD enzyme beneficial?

Because GDH‑FAD is stable and highly selective:

  • It works reliably across wide range of temperatures.1,~
  • It is not affected by oxygen levels in the blood.1
  • It reduces errors caused by substances that could interfere with other types of meters.2

This means more consistent and reliable results for you.

 

Digging Deeper: The Key Role of the Algorithm

Several factors can influence the accuracy of the blood glucose result3 (blood composition, environmental factors such as temperature) and in everyday life, tests rarely happen under perfect conditions. Hands may be a bit cold, the room may be warmer or cooler than ideal, and blood drops can be smaller or uneven. 

The meter’s algorithm (measurement software) is built for these realities: it adjusts the result when the reaction runs too fast or too slow (temperature effects), compensates for small shifts in hematocrit, and filters out signal “noise” caused by normal variability. It also checks if the strip is properly filled for an accurate glucose result.

Together, these automatic corrections reduce the impact of user-related and environmental factors, helping ensure your blood glucose result stays as accurate as possible – even in everyday, imperfect conditions.
 

Why CONTOUR® Meters Make a Difference

Built on decades of research and development, CONTOUR® meters are designed to offer high accuracy and consistency thanks to three key elements:

An advanced enzyme technology2

The GDH-FAD enzyme technology is one of the most reliable in personal glucose monitoring. It reduces interference, stays stable over a wide range of conditions, and reacts specifically to glucose.1,2

A proprietary algorithm

Inside each meter, the algorithm processes the signal from the strip and corrects for natural variations, providing a result you can trust. This is one of the reasons CONTOUR® meters are recognized for their accuracy.

Strict quality standards

CONTOUR® meters and strips are developed and produced in accordance with the current world’s leading medical device standards, including:

  • ISO 13485 for medical device quality
  • ISO 9001 for quality management
  • ISO 14971 for risk control
  • ISO 15197 for blood glucose monitoring systems

These rigorous standards ensure the product is reliable, safe, and consistently accurate.

 

CONTOUR®NEXT GEN: Our Most Accurate Meter Yet

Among the CONTOUR® family, CONTOUR®NEXT GEN provides the highest level of accuracy, with an error margin of only ±5.3%*,†,4, almost three times better than the accuracy standard recognized by Health Canada, which allows a ±15% range.5

This means that when you test your blood sugar, the number you see is very close to your true glucose level. For many people living with diabetes, this level of accuracy offers confidence and peace of mind. Discover why accuracy matters.

Conclusion

A glucose meter works like a tiny lab: blood enters the strip by capillary action, an enzyme reaction produces an electrical signal, and the meter’s algorithm converts that signal into a glucose number in mmol/L. To get results you can trust, keep hands clean and dry, use fresh strips stored correctly, and make sure the strip fills properly. If the number doesn’t fit how you feel, retest or use control solution, then follow your clinician’s advice for targets and treatment decisions.

Discover CONTOUR®NEXT GEN

References:

* Minimum accuracy requirements of ISO15197: 2013 Section 6.3 standard require ≥95% of the measured values to fall within ±0.83 mmol/L at glucose concentrations <5.55 mmol/L or within ±15% ≥5.55 mmol/L of the referenced method.

† >95% of the results were within the error range ±0.3 mmol/L or ±5.3% of the laboratory reference (HK) values for glucose concentrations <5.55 mmol/L or ≥5.55 mmol/L, respectively.

~ Refer to the user guide for more information on the temperature range supported by your meter.

  1. Tsujimura S, Kojima S, Kano K, Ikeda T, Sato M, Sanada H, Omura H. Novel FAD-dependent glucose dehydrogenase for a dioxygen-insensitive glucose biosensor. Biosci Biotechnol Biochem. 2006 Mar;70(3):654-9. doi: 10.1271/bbb.70.654. PMID: 16556981. https://www.tandfonline.com/doi/pdf/10.1271/bbb.70.654
  2. CONTOUR®NEXT Blood Glucose Test Strips Insert, Rev. 04/25.
  3. Diabetes Canada - Using a blood glucose meter and test strips – April 2025. https://www.canada.ca/en/health-canada/services/drugs-health-products/medical-devices/blood-glucose-meters.html
  4. Pleus S et al. User Performance Evaluation and System Accuracy Assessment of Four Blood Glucose Monitoring Systems With Color Coding of Measurement Results. J Diabetes Sci Technol 1-9. 2022.
  5. International Organization for Standardization. In vitro diagnostic test systems – requirements for blood-glucose monitoring systems for self-testing in managing diabetes mellitus (ISO 15197). International Organization for Standardization, Geneva, Switzerland, 2013.