A glucometer is a meter that measures blood glucose levels.
Today’s meters come in all kinds of forms, from talking and large-display meters to those that light up (for testing in the middle of the night, if necessary).
Some also have built-in food databases and record-keeping systems.
Almost all glucometers measure plasma glucose results by taking the value derived from a drop of whole blood and adding 12 percent to the measured value.
For most meters, this is equivalent to a reading that a laboratory obtains.
A glucometer (right) and syringe.
Where does one purchase glucometers?
Most glucometers are found at pharmacies and clinics, and many of them are free through special offers from the manufacturer. (It is the test strips used in the glucometers that often are the more costly items, since many people with diabetes have to test their blood glucose levels several times a day.) Some meters also have mail-in rebates after the meter is purchased, and some even offer trade-in rebates if a person has an older machine.
For the coverage of diabetes supplies, such as test strips, patients should contact their insurance company to see what is covered (if anything).
At this writing, for people on Medicare, the program will cover the costs of blood testing supplies for people with diabetes.
What is a continuous glucose monitor (CGM)?
A continuous glucose monitor tracks a person’s glucose levels every few minutes.
It is also often used in conjunction with a regular blood glucose meter (that does not continuously monitor glucose levels).
Once used mainly for young children (especially for nighttime monitoring) and less mobile people, the technology has improved enough for many others to use the device, such as diabetics who travel extensively, who have an active lifestyle, or who can’t stop and monitor their blood glucose levels as much.
The monitors have a small filament with a sensor that is inserted just below the skin, usually in an unobtrusive spot, such as just above or below the waist.
Using a small radio transmitter, the sensor sends information to a handheld receiver; an iPhone, tablet, or computer can receive the data.
The receiver displays the person’s glucose level every few minutes.
Depending on the model, special alarms can alert the person to fluctuations in blood glucose levels, especially drops in levels that can lead to hypoglycemia.
What should a person look for when choosing a glucometer?
Choosing a glucose meter is mostly a personal choice (but not always, especially when certain health insurance companies cover only specific types of glucometers).
There are some features to think about before picking a meter, including the speed (meters can take anywhere from five to 20 seconds to show results); a beeping or silent monitor for prompts; type of test strips (wrapped or not); or a meter with a memory.
Other things to consider include how much the meter has to be cleaned; how portable it is (especially for travel); whether the meter checks for glucose and ketones; the size of blood sample the meter needs; and the types of (and ease of finding) batteries the meter uses.
There are more considerations, but these are the most common.
In general, how much fluctuation is there in glucometer readings?
No machine is perfect, and glucometers are no exception. Even if a glucometer is cleaned and calibrated regularly, it may vary in accuracy from other meters, perhaps by as much as 20 percent. If a person with diabetes has any question about the accuracy of a glucometer, it is best to have the device checked out by a health care professional, pharmacy, or diabetes educator.
Can test strips give erroneous readings?
Yes, test strips can give a person with diabetes erroneous readings for a number of reasons.
For example, the test strips may be too old.
The enzymes that are embedded in the test strip can lose their activity and cause bare spots on the strips, giving an erroneous reading.
A person may use the wrong test strips for the glucometer, giving a false or inaccurate reading, or no result. (This is usually because every machine has its own special test strips.) Abnormal readings may also occur if the temperature is too low.
Low temperatures often affect the ability to draw blood for testing (blood does not circulate as close to the skin’s surface in lower temperatures as it does in higher temperatures).
Lancets allow you to make a clean, safe prick on the finger to draw a blood sample for testing.
What is a lancet?
In order for patients to get a clean prick of the finger to obtain a blood sample for a glucometer, many companies provide a lancing device, commonly called a lancet. This tool for pricking a finger is usually ad-justable to varying depths into the skin, depending on the individual’s need. The lancet needle has a release button, pricking the finger quickly. For most people, this way of obtaining a drop of blood is easy, fast, and clean.
What are some general steps when a person with diabetes takes his or her blood glucose level?
There are some very general steps a person with diabetes can take when using a blood glucose meter. Some people may have to take other steps, so it is best to check the procedure with a health care professional).
• The first step is having everything out that the person will need to take his or her levels, such as the meter, unused test strips, unused lancets, and alcohol swabs. (Make sure the meter’s batteries are charged.)
• Next, the person should make sure his or her hands are clean and free of anything that could influence the meter’s reading. (It is best to wash the hands in warm water.)
• After drying the hands, the person may shake the hands below the waist, then squeeze (some people refer to it as “milking”) the fingers a few times before using the lancet. This helps to bring the blood flow to the fingertip. (Blood samples are most often taken at the fingertips, where there are fewer nerve endings.)
• The lancet device is then put on the side of the fingertip, and the release button on the lancet is pushed. As a small drop of blood appears, it can be helped along if the person gently squeezes from the base of the finger toward the tip until a good drop of blood appears.
• From there, the test strip essentially sucks up the drop of blood, and the meter is set to read the blood glucose level.
• At this point, some meters will digitally record the person’s blood glucose data for each day. Other meters just give the blood glucose number, meaning it is up to the person to record and keep track of the blood glucose numbers each day (many glucometers come with a free log book).
What events and actions can often throw off blood glucose levels?
Several events and actions can throw off a person’s blood glucose levels, no matter how well the person monitors his or her blood glucose. Ordinary or non-ordinary events such as stress, certain illnesses, unanticipated activity, menstruation, eating, alcohol, or medications can throw the blood glucose levels off balance and cause (sometimes dangerous) fluctuations.
What medical conditions can lead to erroneous readings on a glucometer?
Several medical conditions a person with diabetes can have affect the readings on a glucometer. For example, blood disorders can cause inaccurate readings, such as in people who are anemic whose readings are often falsely high. A person with high levels of hemoglobin in the blood (polycythemia) can experience false low readings. If a person is dehydrated or in shock, he or she may also have false or abnormal glucometer readings.
Do blood glucose meters measure ketones?
Y es, some blood glucose meters measure ketones.
This is important to people with diabetes, especially for people with type 1 diabetes.
The meters use special blood ketone strips, with the level of ketones shown as a number on the meter display.
In most cases, if the ketone reading is moderate or high, and a person’s blood sugar is also high, the person should receive medical attention immediately as high ketones indicate possible diabetic ketoacidosis (for more about diabetic ketoacidosis, see the chapter “Type 1 Diabetes”).
What other things can interfere with blood glucose readings on a glucometer?
Many things can interfere with blood glucose readings on a glucometer.
For example, acetaminophen (commonly referred to as Tylenol) and acetaminophen-containing drugs (some over-the-counter cough and cold medications contain the drug, as do some prescription pain medications such as Zutripro) can interact with certain chemicals used in various medical devices.
This interaction can cause the person’s blood glucose levels to rise, interfering with the correct readings.
In addition, if a person does not clean his or her hands before collecting a blood sample, incorrect readings can result (the more recent meters only need a small sample, and if it is contaminated with other chemicals or dirt, it can throw off the reading).
Other more technical conditions may lead to false blood-sugar readings.
For example, glucose meters vary in the way they work and are calibrated.
Failure to calibrate the meter regularly can lead to false blood glucose readings.
Why do many doctors suggest that blood samples for a glucometer be taken from a person’s fingertips?
For some blood glucose meters, there is a reason for taking most of the blood samples from the person’s fingertips, obtaining it in almost any other part of the body (unless it is necessary) can result in a false reading. That being said, many of the more modern glucose monitors require a tiny blood sample, some as small as a third of a microliter. For many of these machines, the small sample can be taken from other sites on the body, such as the forearm or thigh.
How many times a day should a person with diabetes test his or her blood glucose levels?
There is no set number of times a day that blood glucose levels should be tested.
This is because everyone’s needs and blood glucose levels are different.
Some health care professionals suggest monitoring after a meal; others advocate testing as many times as possible throughout the day.
Most believe it is a good idea to check glucose levels before a person drives, exercises, uses heavy equipment, or performs any high-risk task.
But overall, the number of times a person monitors glucose levels depends on the individual, the extent of the diabetes, and the recommendations of health care professionals and diabetes-care team.
Taking blood from the tip of one’s finger provides the most accurate readings of glucose levels.
Who should test their blood glucose levels on a regular basis?
Although not all people with diabetes need to diligently self-monitor their blood sugar levels, whether they should or not seems to depend on what type of diabetes a person develops. Most health care professionals suggest that people who take insulin should test their blood sugar regularly. Those who take oral diabetes medication for type 2 diabetes should test their levels frequently, especially if they are taking sulfonylureas or glinides, both of which can occasionally cause low blood sugar.
In addition, Harvard Medical School suggests that certain situations warrant more frequent testing of blood sugar levels, including very high levels at the time diabetes is diagnosed, recent weight gain or loss (not explained by dieting or stress), exercising more than usual (or even less than usual), a change in a person’s diabetic medications (especially sulfonylureas and glinides), and during an illness, such as a gastrointestinal virus (because even a flu or cold can cause blood sugar levels to fluctuate).