The devices in the FDA-sponsored study included the widely used meters equipped with reflectance photometers, which measure light reflected from a reagent strip after it has undergone a chemical reaction. Microcurrent meters, which use a new technology to gauge the electric current produced by the blood resting on the tip of the test strip, were also included in the study.

Liquid crystal displays, which are crucial to the successful use of the meters, were found almost uniformly to perform within acceptable limits. All displays were found to be legible even when viewed in direct sunlight.

But most of the meters contained engineering and design characteristics that made SMBG complicated for the users. Some control or button labels were too difficult to read, and some of the buttons were not arranged in the order in which they are routinely used.

More problematic were the relatively faint beeps that alert the user to the various steps in the monitoring process. Diabetics with poor vision may have difficulty reading the instructions on the display and thus rely more heavily on the audible tones of the meter. According to the survey, "tones produced by one half of the meters could not be readily heard over a normal conversation five feet away." Another problem identified by the human factors study was that routine replacement of batteries required "too much fine motor coordination and was quite difficult for some users."

Instruction Manuals

The 11 manuals analyzed by FDA presented still more obstacles for at least some users of the meters. Some were printed in letters smaller than the 10 to 12 point size recommended for the greatest reading ease. (For comparison, the letter size on this page is 10 points.) Graphics — especially important for people who have poor reading skills — were relatively scant. FDA staff believe that for most of the manuals, improved nonverbal instructions would be helpful.

The scarcity of explanatory pictures was particularly troubling because of the overall low readability scores of the manuals. As the study notes, information in instructions should be "inherently clear to the user," and medical or technical terms should be minimized. Yet, phrases such as "programming sets the instrument's electronics to match the reactivity" or "all informational digits are functioning" were common in several manuals.

Because the reading comprehension of the average American adult is below the ninth grade level, it is usually recommended that instructional material be written at the sixth-grade level. The reading-grade level of the examined manuals ranged from the late seventh grade, with an average score of late ninth grade.

"Efforts are needed to improve the readability of most manuals," the preliminary study concluded. Another important recommendation called for the inclusion of information about the most common testing pitfalls and how to correct them.

Corrections Under Way

After a three-year search by FDA to identify the causes of user errors in SMBG, remedies are under way. Several manufacturers of blood glucose meters have already begun improving features of the meters and instructional materials identified by the San Diego researchers. Complicated procedures are being reduced, and instruction manuals, tested by meter users, have improved formats with clear illustrations. Manufacturers' 800 phone numbers are now available to help users with problems in SMBG.

To zero in on the users' mistakes in the monitoring, FDA plans a workshop in May 1990 with health professionals, meter manufacturers, and other groups involved in the care of diabetics. The goal of the workshop is to develop SMBG educational and training strategies that would be made available nationwide to diabetics.

Meter Monitoring Tips

If you suspect a reading is in error:

• Check the calibration of the meter.
• Conduct a control test.
• Repeat your blood glucose test.
• Call a diabetes health professional or the meter manufacturer's 800 number for help.

Tips for reducing user errors:

• Obtain professional training and guidance.
• Use fresh strips and supplies.
• Clean your meter frequently.
• Check your SMBG technique routinely with a professional.
• Follow the manufacturer's instructions carefully.

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Tags: Diabetes

About the Author

FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.