Errors in Using Blood Glucose Monitors in Hospitals
Hazard [Health Devices Apr 1996;25(4):150]
Between 1994 and 1996, the U.S. Food and Drug Administration (FDA) has
received more than 400 medical device reports on blood glucose monitors (BGMs), and ECRI
continues to receive reports of errors involving the use of these units in hospitals. The
most common errors include the following:
- Incorrect quality control (QC) or proficiency
testing procedures (e.g., not following manufacturer recommendations,
incorrectly performing procedures)
- Improper technique (e.g., fingerstick, timing,
- Incorrect match between monitor calibration and
test-strip calibration (e.g., using the wrong calibration code for a lot of
- Inadequate cleaning
- Inappropriate procedures for comparing BGM results
with laboratory results
These errors can lead to inaccurate blood glucose readings that, if not
detected, may result in inappropriate patient therapy (e.g., unnecessary insulin
BGMs, which are used to measure blood glucose concentrations, play a
critical role in diabetes management. On most BGMs, a drop of whole blood is placed on a
blood glucose test strip (compatible with the BGM) before or after the strip is inserted
into the monitor to determine the blood glucose concentration. On some units, the user
must manually wipe excess blood from the test strip before inserting it in the BGM; on
others, this step is unnecessary.
Hospitals have guidelines and policies in place for using BGMs. However,
errors can increase when many different people use the units and when many different BGM
brands are used. Effective BGM testing requires coordination of the procedures of several
different hospital departments (e.g., clinical laboratory, nursing, emergency, biomedical
engineering) to ensure that the devices are properly used, calibrated, and maintained.
Frequent in-service training is required for hospital personnel and should help to
minimize problems in using BGMs.
Our recommendations are adapted from our Evaluation of blood glucose
monitors (Health Devices
23, March 1994). Hospitals should ensure that all staff
using these units follow our recommendations, which cover four basic areas:
1. Training and education.
- Alert all department managers and the laboratory
manager to any problems involving BGM use and have them ensure that the
staff is adequately trained to prevent such problems.
- Properly train all BGM users, preferably through
one-on-one or classroom education. Training should include any instructional
information provided with the BGM, including audiotapes and videotapes.
Periodically monitor user performance to determine if additional training is
- When a new BGM model is first introduced into the
hospital, ensure that users practice with a control solution compatible with
that BGM until they obtain consistent results (within 10%).
- Provide training on appropriate fingerstick
sampling techniques. Ensure that a clean, dry puncture site is used to avoid
alcohol contamination in the blood sample.
- Follow appropriate QC and proficiency testing
procedures specified by the manufacturer and established by your
2. Use of test strips and control
- Use only those test strips and control solutions
intended for use with the model or type of BGM you are using.
- Use only test strips or control solutions that are
current (i.e., within the manufacturer-stated expiration date) and document
the date on which a new lot of strips goes into use.
- Use only test strips for which a calibration code
or chip has been entered into the monitor, if the unit is so designed.
- Store test strips in their container with the cap
tightly closed. Reclose the cap immediately after removing a strip. Store
strips only at temperatures specified by the manufacturer.
- Use the test strips immediately after removing them from the
container. If they have been refrigerated, allow them to reach room temperature before opening the package. Minimize
the strips' exposure to moisture and bright light (especially sunlight).
- Apply enough blood to adequately fill or cover the
reagent area. Touch the drop of blood to the pad; do not smear it, unless
the manufacturer's instructions say to do so.
- If using a BGM that requires manual wiping of the
test strip, be sure that the correct technique and wiping material are used
for the BGM in question.
- Because QC solutions or check strips may have a
wide blood glucose range, consider developing your own ranges. (New ranges
can be developed by the ancillary testing coordinator or the laboratory
3. Cleaning and infection
- Clean the monitor at intervals recommended by the
manufacturer, or more frequently if needed.
- Follow appropriate infection control procedures as
recommended by the manufacturer for the lancing device and
4. Comparing BGM and laboratory
- Periodically compare the monitor's results with the
clinical laboratory's results. Be aware, however, that a discrepancy is
possible between results on your BGM and those from the lab. For example,
whole blood is sometimes used on the BGM while plasma is used in the
laboratory testing; this can produce differences of as much as 11%. Other
factors contributing to discrepancies can include the type of blood (e.g.,
capillary versus venous sample) collected for the laboratory, whether a
fasting or nonfasting specimen is used, how and when blood is collected, the
time elapsed between blood draw and blood analysis in the laboratory, and
the type of blood preservative used in the blood collection tube.
- Periodically review the entire quality assurance
process that is used to compare BGM results with laboratory results,
including the factors listed in previous item. (The process can be reviewed
by the ancillary testing coordinator or the laboratory manager.)
- Check BGM results against laboratory results for patients
with known or suspected interfering substances (e.g., hematocrit, uric acid, bilirubin,
high medication dose, abnormal PO2).
Joint Commission on Accreditation of Healthcare Organizations (JCAHO). Accreditation
manual for pathology and clinical laboratory services. PA-101. 1996.
National Committee for Clinical Laboratory Standards (NCCLS). Ancillary
(bedside) blood glucose testing in acute and chronic care facilities [Approved
guideline]. C30-A. 1994.
- Blood Glucose Monitors, Portable [16-488]
- Reagents, Strip, Glucose [17-419]
Cause of Device-Related Incident
Device factors: Improper maintenance,
testing, repair, or lack or failure of incoming inspection; Manufacturing error
User errors: Failure to read label; Incorrect clinical use
Support system failures: Error in hospital policy; Failure to train and/or credential
Mechanism of Injury or Death
Failure to deliver therapy; Overdose; Underdose