Diabetes: Choosing and Using Your Glucose Meter (cont.)

How FDA Regulates Glucose Meters

FDA reviews all glucose meters and test strips before they can be marketed to the public. This FDA "premarket" review process requires the manufacturer of the meter to show that the meter system provides acceptable accuracy and consistency of glucose measurement at high, medium and low levels of glucose as compared to glucose meters already being sold. The quality of software is an increasingly important feature of glucose meters since it controls the testing and data storage and controls the displays that the user sees and uses when testing.

FDA also considers possible interference from over-the-counter medications, prescription medications, and vitamin supplements.

FDA also asks for data showing how well the meter has performed during actual use (a type of human factors study). These studies ensure that users understand the labeling, achieve good results, and avoid experiencing problems that could affect their health.

Reporting Problems with Glucose Meters to FDA

FDA learns about problems with medical products through the MedWatch program. Consumers can report problems with medical devices, including glucose meters, through MedWatch.

For general information about the MedWatch program and instructions for reporting problems with medical devices, use the following link:

MedWatch: The FDA Safety Information and Adverse Event Reporting Program http://www.fda.gov/medwatch/how.htm

For further information about how medical device problems are reported to FDA, use the following link:

Reporting Problems with Medical Devices http://www.fda.gov/cdrh/mdr.html

Performance Goals for Glucose Meters

Deciding performance standards for glucose meters has been controversial and challenging. In spite of effort in the late 1970s and 1980s by both FDA and CDC, no universally accepted standards or testing methods have been developed for the measurement of glucose. CDC (Centers for Disease Control and Prevention) recently held a standards conference and is exploring the possibility of developing a standard reference material for whole blood.

The ADA has recommended accuracy goals twice over the past twenty years, once in 1986 (target accuracy of +/- 15%) and once in 1993 (target accuracy of +/- 5%) No company that manufacturers glucose meters has developed a cost-effective system to meet these goals. A number of alternative standards have been suggested by national standards organizations in the U.S., Canada, and Europe. An international standard ISO DIS 15197 is currently under development that recommends accuracy of +/- 20 mg/dl for glucose values under 100 mg/dl and +/- 20% for higher glucose values.

Although data on glucose meters continue to show variable performance, the newest generations of meters are simpler to use and more accurate than older models. Improvements in the chemical, mechanical and software components of glucose meters are continuing to help with the management of diabetes.

Other Diabetes Management Tests

Glycosylated Hemoglobin

There is hemoglobin in all red blood cells. Hemoglobin is the part of the red blood cell that carries oxygen to the tissues and organs in the body. Hemoglobin combines with blood glucose to make glycosylated hemoglobin or hemoglobin A1c.

Red blood cells store glycosylated hemoglobin slowly over their 120-day life span. When you have high levels of glucose in your blood, your red blood cells store large amounts of glycosylated hemoglobin. When you have normal or near normal levels, your red blood cells store normal or near normal amounts of glycosylated hemoglobin. So, when you measure your glycosylated hemoglobin, you can find out your level of blood glucose, averaged over the last few months.

Doctors have used the glycosylated hemoglobin test for patients with diabetes since 1976 (1,2). The test is now widely used in the routine monitoring of patients with diabetes mellitus. Your doctor may use this test to see how well you respond to treatment. If you have low test values you probably have lowered risk for having complications from diabetes mellitus.

It is good to have your glycosylated hemoglobin tested at least two times a year if you meet your treatment goals or up to four times a year if you change therapy or do not meet your treatment goals. There are now many different ways to measure glycosylated hemoglobin. These tests vary in cost and convenience and you can do some at home. The values (glycosylated hemoglobin index) these tests give can vary too. Talk to your doctor about what your glycosylated hemoglobin index should be.

Patients with diseases affecting hemoglobin, such as anemia, may get wrong values with this test. Vitamins C and E, high levels of lipids, and diseases of the liver and kidneys may all cause the test results to be wrong.

Glycosylated Serum Proteins

Serum proteins, like hemoglobin, combine with glucose to form glycosylated products. Testing these glycosylated products can give information about your glucose control over shorter periods of time than testing glycosylated hemoglobin.

One common test is the fructosamine test. It gives information on your glucose status over a one- to two-week period. High values mean your blood glucose was high over the past two weeks. This test is good for watching short-term changes in your glucose status during pregnancy or after major changes in your therapy. There is no general guideline for when to use this test. Talk to your doctor about whether this test is right for you.