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When people with diabetes can control their blood sugar (glucose), they are more likely to stay healthy. People with diabetes use two kinds of management devices: glucose meters and other diabetes management tests. Glucose meters help people with diabetes check their blood sugar at home, school, work, and play. Other blood and urine tests reveal trends in diabetes management and help identify diabetes complications.
Other Diabetes Management Tests
Self-Monitoring of Blood Glucose The process of monitoring one's own blood glucose with a glucose meter is often referred to as self-monitoring of blood glucose or "SMBG." Portable glucose meters are small battery-operated devices. For a picture of a portable blood glucose meter, use the following link:
To test for glucose with a typical glucose meter, place a small sample of blood on a disposable "test strip" and place the strip in the meter. The test strips are coated with chemicals (glucose oxidase, dehydrogenase, or hexokinase) that combine with glucose in blood. The meter measures how much glucose is present. Meters do this in different ways. Some measure the amount of electricity that can pass through the sample. Others measure how much light reflects from it. The meter displays the glucose level as a number. Several new models can record and store a number of test results. Some models can connect to personal computers to store test results or print them out.
At least 25 different meters are commercially available. They differ in several ways including
To search FDA's 510(k) database for glucose meters available over-the-counter (without a prescription), use the following link:
Newer meters often have features that make them easier to use than older models. Some meters allow you to get blood from places other than your fingertip (Alternative Site Testing). Some new models have automatic timing, error codes and signals, or barcode readers to help with calibration. Some meters have a large display screen or spoken instructions for people with visual impairments.
Diabetes care should be designed for each individual patient. Some patients may need to test (monitor) more often than others do. How often you use your glucose meter should be based on the recommendation of your health care provider. Self-monitoring of blood glucose (SMBG) is recommended for all people with diabetes, but especially for those who take insulin. The role of SMBG has not been defined for people with stable type 2 diabetes treated only with diet. As a general rule, the American Diabetes Association (ADA) recommends that most patients with type 1 diabetes test glucose three or more times per day. Pregnant women taking insulin for gestational diabetes should test two times per day. ADA does not specify how often people with type 2 diabetes should test their glucose, but testing often helps control. Often, self-monitoring plans direct you to test your blood sugar before meals, 2 hours after meals, at bedtime, at 3 a.m., and anytime you experience signs or symptoms. You should test more often when you change medications, when you have unusual stress or illness, or in other unusual circumstances.
Learning to Use Your Glucose Meter Not all glucose meters work the same way. Since you need to know how to use your glucose meter and interpret its results, you should get training from a diabetes educator. The educator should watch you test your glucose to make sure you can use your meter correctly. This training is better if it is part of an overall diabetes education program. For information about diabetes education programs recognized by the American Diabetes Association, use the following link:
The following are the general instructions for using a glucose meter: 1. Wash hands with soap and warm water and dry completely or clean the
area with alcohol and dry completely. FDA requires that glucose meters and the strips used with them have instructions for use. You should read carefully the instructions for both the meter and its test strips. Meter instructions are found in the user manual. Keep this manual to help you solve any problems that may arise. Many meters use "error codes" when there is a problem with the meter, the test strip, or the blood sample on the strip. You will need the manual to interpret these error codes and fix the problem. You can get information about your meter and test strips from several different sources. Your user manual should include a toll free number in case you have questions or problems. If you have a problem and can't get a response from this number, contact your healthcare provider or a local emergency room for advice. Also, the manufacturer of your meter should have a website. Check this website regularly to see if it lists any issues with the function of your meter. New devices are for sale such as laser lancets and meters that can test blood taken from "alternative sites" of the body other than fingertips. Since new devices are used in new ways and often have new use restrictions, you must review the instructions carefully.
There are several features of glucose meters that you need to understand so you can use your meter and understand its results. These features are often different for different meters. You should understand the features of your own meter.
The accuracy of your test results depends partly on the quality of your meter and test strips and your training. Other factors can also make a difference in the accuracy of your results.
The FDA's Center for Devices and Radiological Health (CDRH) held a series of focus groups on blood glucose meter use in 2001. The twenty-two members participated in six groups. They were all government employees, mostly from CDRH. They were either people with diabetes or family members of people with diabetes who were familiar with the use of glucose meters. Most of the participants in these groups were satisfied with their meters. Some were quite enthusiastic about the new models. A few had some concerns about meters. One such participant stated: "The first meter I got I couldn't use because it was too difficult."
Some glucose meters allow testing blood from alternative sites, such as the upper arm, forearm, base of the thumb, and thigh Sampling blood from alternative sites may be desirable, but it may have some limitations. Blood in the fingertips show changes in glucose levels more quickly than blood in other parts of the body. This means that alternative site test results may be different from fingertip test results not because of the meter's ability to test accurately, but because the actual glucose concentration can be different. FDA believes that further research is needed to better understand these differences in test values and their possible impact on the health of people with diabetes. Glucose concentrations change rapidly after a meal, insulin or exercise. Glucose levels at the alternative site appear to change more slowly than in the fingertips. Because of this concern, FDA has now requested that manufacturers either show their device is not affected by differences between alternative site and fingertip blood samples during times of rapidly changing glucose, or alert users about possible different values at these times. Recommended labeling precautions include these statements:
In October, 2001, FDA held a public meeting to discuss the types of information and labeling needed for glucose measuring devices if the blood sample is taken from alternative sites rather than the fingertip. Presenters included manufacturers of blood glucose meters, healthcare providers, people with diabetes, and parents of children with diabetes. For more information about the panel meeting on alternative site testing, use the following link: Clinical Chemistry and Clinical Toxicology Devices Panel Meeting Summary
for October 29, 2001
Researchers are exploring new technologies for glucose testing that avoid fingersticks. One of these is based on near-infrared spectroscopy for measurement of glucose. Essentially, this amounts to measuring glucose by shining a beam of light on the skin. It is painless. There are increasing numbers of reports in the scientific literature on the challenges, strengths, and weaknesses of this and other new approaches to testing glucose without fingersticks. FDA has approved one "minimally invasive" meter and one "non-invasive" glucose meter. Neither of these should replace standard glucose testing. They are used to obtain additional glucose values between fingerstick tests. Both devices require daily calibration using standard fingerstick glucose measurements and both remain the subject of continuing studies to find how they are best used as tools for diabetes management.
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. For an outline of the FDA review process for glucose meters, use the following link:
For information about the application of human factors to the design of medical devices, use the following link:
FDA quality system regulations require that manufacturers who make glucose meters follow the same quality standards every time. In this way, users can be assured that new meters and strips perform as well as older models. FDA's responsibility for medical devices does not end when the devices enters the market. To monitor the quality of products, FDA routinely inspects manufacturing facilities. It also receives information from the manufacturers, health providers and the general public through the MedWatch system.
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:
For further information about how medical device problems are reported to FDA, use the following link:
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.
Anton Hubert Clemens received the first patent for a blood glucose meter called the Ames Reflectance Meter on September 14, 1971. Richard K. Bernstein, an insulin dependent physician with diabetes, was one of the first patients to monitor his blood glucose at home using a glucose meter. He published a report on his experiences in an early volume of the medical journal, Diabetes Care. He has also written a book on this subject "Dr. Bernstein's Diabetes Solution: A Complete Guide to Achieving Normal Blood Sugars". The first articles in the medical literature on the home blood glucose monitoring were published in 1978 (references 1-5). These demonstrated that patients could reliably measure their blood glucose levels at home and improve control of their glucose levels. In November 1986, the American Diabetes Association, the Centers for Disease Control and Prevention, the Food and Drug Administration, and the National Institutes of Health convened a Consensus Conference on Self-Monitoring of Blood Glucose. The results of that conference was that self-monitoring of blood glucose was an exciting and important tool for effective management of patients with diabetes (reference 6). It was recommended that SMBG be used by patients to accomplish the following goals: (a) Keep track of their glucose levels over time, SMBG was first used because health care providers and researchers believed that its use would help with glucose control and that better glucose control would reduce or prevent diabetes complications. In other words, if hyperglycemia (too much glucose in the blood) and hypoglycemia (too little glucose in the blood) could be controlled, people with diabetes would remain healthier. This expectation was shown to be true in 1993, when the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) published results of a large and conclusive study called the Diabetes Control and Complications Trial (DCCT), which involved patients at 29 medical centers in the United States and Canada. In this study, SMBG was an important part of the glucose control strategy. This study showed that for persons with type 1 diabetes, intensive treatment to keep blood glucose levels close to normal reduced the rate of diabetic complications. In fact, the risk reduction was 76% for eye disease, 50% for kidney disease, and 60% for nerve disease. These benefits of tight control of glucose were not problem-free however. Patients in the intensive treatment group had an increased risk of hypoglycemia. In September 1993 the American Diabetes Association held a second Development Conference on Self-Monitoring of Blood Glucose. This conference noted that SMBG was an important component of the treatment plan of patients with diabetes mellitus and four major reasons for using SMBG were discussed: (a) Controlling glucose at a specific, healthy level, Currently, the market for blood glucose meters is several billions dollars per year worldwide and growth continues. References 2. Skyler JS et al: Home blood glucose monitoring as an aid in diabetes
management. Diabetes Care 1:150-157, 1978. 4. Walford S et al: Self-monitoring of blood glucose -- improvement of diabetic control: Lancet 1: 7320735, 1978. 5. Peterson et al: Feasibility of tight control of juvenile diabetics through patient-monitored glucose determinations. Diabetes 27(suppl 2): 437, 1978. 6. Ikeda Y et al: Pilot study of self-measurement of blood glucose using the Dextrostix-Eyetone system for juvenile-onset diabetes. Diabetologia 15:91-93, 1978.
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. References 1. Bunn HF, Haney DN, Kamin S, et al: The biosynthesis of human hemoglobin A1C: slow glycosylation of hemoglobin in vivo. J Clin Invest 57(6):1652-9, 1976. 2. Fabbay KH: Editorial: Glycosylated hemoglobin and diabetic control. N Eng J Med 295(8):443-4, 1976. For more information about the glycosylated hemoglobin test (HbA1c), use the following links:
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. If you have any other disease that can change your serum proteins or if you have large amounts of Vitamin C (ascorbic acid) in your diet, these tests may give wrong values. For more information about the fructosamine test, use the following link:
Only patients who are unable to use blood glucose meters should use urine glucose tests. Testing urine for glucose, which was once the best way for patients to manage their diabetes, has mostly now been replaced by self-monitoring of blood glucose. There are three major drawbacks of urine glucose testing compared to blood testing. First, urine glucose testing will not tell you about low (below 180 mg/dl) glucose levels, since at lower levels glucose does not enter your urine. Second, urine glucose readings change when the volume of your urine changes. Third, your urine glucose level is more of an average value than your blood glucose level. There are several dipstick tests available on the market. For more information about measuring glucose in urine, use the following link:
When the body does not have enough insulin, fats are used for fuel instead of glucose. A by-product of burning fats is the production of ketones. Ketones are passed in the urine and can be detected with a urine test. If you do not have diabetes, you usually have only small amounts of ketones in your blood and urine. If you have diabetes, however, you may have high amounts of ketones and acid, a condition known as ketoacidosis. This condition can cause nausea, vomiting, or abdominal pain and can be life threatening. You may use urine dipsticks to rapidly and easily measure the ketones in your urine. You dip a dipstick in your urine and follow the instruction on the package to see if you have a high amount of ketones. If you have type 1 diabetes, are pregnant with preexisting diabetes, or who have diabetes caused by pregnancy (gestational diabetes), you should check your urine for ketones. If you have diabetes and are ill, under stress, or have any symptoms of high ketones, you should also test your urine for ketones. Results of ketone testing should be interpreted with care. High ketone levels are found when patients are pregnant (in the first morning urine sample), starving, or recovering from a hypoglycemic episode. There are now tests for measuring ketones in blood that your doctor may use or you can use at home. Some measure a specific ketone (beta-hydroxybuyric acid) that patients with diabetic ketoacidosis may have. It is still not known which type of ketone test -blood or urine-- offers more aid to people with diabetes. For more information about ketone tests, use the following links:
One common and extremely serious result of diabetes is kidney failure. Under normal conditions, the kidneys filter toxins from the blood. When the kidney's filtering processes begin to become impaired, protein (microalbumin) begins to spill into the urine. Testing urine for small, yet abnormal amounts of albumin (microabluminuria) is a common way to detect this condition early, before it can damage your kidneys. Many urine dipsticks are used to test for large amounts of albumin. To measure a small amount of albumin, which may show an early stage of kidney disease, your health care provider may use specific tests for low levels of albumin (microalbumin tests). To do this test, you may have to collect your urine for several 24-hour periods. The ADA recommends that adults with diabetes be tested for microalbumin every 3- to 6-months. The ADA recommends testing in children with type 1 diabetes at puberty or after having diabetes for 5 years. Early detection of microalbumin is important because it indicates increased risk for both renal and vascular disease. Fortunately, early detection allows for treatments that may delay the beginning of a more serious disease. For more information about microalbumin tests, use the following link:
If you have diabetes, you have a higher risk of heart and blood vessel disease (cardiovascular disease). One way to limit this risk is to measure your cholesterol routinely and control it by changing your lifestyle or taking prescription drugs. A cholesterol test usually shows your total cholesterol, total triglycerides, and high-density lipoproteins (HDLs). The Centers for Disease Prevention and Control (CDC) has set up a National Reference System for Cholesterol Testing and many manufacturers verify their test through certification with this method. For more information about cholesterol testing, use the following link:
Updated 5/1/02 |
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