Blood glucose monitors and accuracy
The topic of blood glucose monitoring and accuracy has been one of major concern with the continuing development of new blood glucose monitors. Indeed, I am often questioned why upon paired testing, one meter reading may be quite different from another. Generally, glucose meters are utilized to base insulin dosing as well as to monitor glucose trends. Thus, accuracy of meter blood glucose readings is extremely important in order to bolus the correction appropriately. In addition, if there is a 20 to 30 percent range of accuracy, just what becomes a low or high blood sugar?
In September 2013, the American Association of Diabetes Educators issued a Practice Advisory in regard to blood glucose accuracy. Glucose meters, as with other durable medical equipment, are regulated by the US Food and Drug Administration (FDA) using International Organization for Standardization (ISO)15197:2003 "Requirements for blood monitoring systems for self-testing in managing diabetes mellitus." The ISO standard requires that 95 percent of the results be within range or slightly elevated to be 20 percent lower or higher of the true value.
In 2013, the Diabetes Technology Society presented several studies that demonstrated many glucose meters to "fall short of the 95 percent accuracy required by the FDA." Therefore, The ISO published a revised 15197:2013 standard that had stricter accuracy guidelines for blood glucose meters. The main differences from the 2003 version are as follows:
- Increased accuracy for blood glucose meters, specifically for glucose values greater than 75 mg/dl
- Blood glucose manufacturers must ensure that their technology enables accuracy to improve from 20 percent higher or lower to 15 percent higher or lower than true value
- 99 percent of the results versus 95 percent of the results must be within range or slightly elevated
- Formal acceptance criteria for accuracy of testing by patients and assessment of interfering agents that may decrease meter accuracy (i.e., Hematocrit)
- Interfering agents that affect accuracy:
- Poor quality of test strips
- Unwashed hands before testing
- Damp testing site from pretest alcohol swab
- Hematocrit levels secondary to dehydration or anemia
- Interfering substances such as vitamin C, acetaminophen, or uric acid
- Altitude, temperature, and humidity
- Poor storage and handling
- Changing test site location (alternating testing site may not note low blood sugars)
- Improperly-calibrated meter
- Insufficient blood applied to strip
The latest update in regard to meters and accuracy was released on May 20, 2014 by the Diabetes Technology Society in which they announced the launch of the Diabetes Technology Society (DTS) Surveillance Program for Cleared Blood Glucose Monitors. According to the DTS, the intent of the program is to protect patients from inaccurate blood glucose meter products that are currently on the market. According to the DTS, the surveillance program "will provide independent assessment of the performance of the cleared blood glucose monitors following the FDA clearance against accepted standards, and generate information that can assist patients, healthcare providers, and payers in making the right product selection."
There will be the formation of a steering and advisory committee that will consist of experts in blood glucose monitoring for academia, medical practice, clinical chemistry, government, industry, and medical organizations, as well as the development of patient advocacy groups. According to the DTS, the FDA supports a blood glucose monitoring surveillance program to protect public health. Lastly, and most importantly, the FDA has stated that it will act on information that it receives on low-quality blood glucose monitoring products based on surveillance testing. My understanding is that Abbott labs have provided initial funds, and this project will begin later this month.
Data for individual meters can be found in the following reference:
Freckmann G, Baumstark A, Jendrike N, Zschornack E, Kocher S,
Tshiananga J, Heister F, Haug C. System accuracy evaluation of 27 blood glucose monitoring systems according to DIN EN ISO 15197. Diabetes Technol Ther. 2010 Mar;12(3):221-31. doi:
Fran Cogen, M.D., C.D.E., is the director of the Childhood and Adolescent Diabetes Program at Children’s National Health System. She wrote about diabetes for HealthCentral.