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Checking Your Blood Glucose
Blood glucose (blood sugar) monitoring is the main tool you have to check your diabetes control. This check tells you your blood glucose level at any one time.
Keeping a log of your results is vital. When you bring this record to your health care provider, you have a good picture of your body's response to your diabetes care plan. To help keep track of your levels, we have an online tool
or a . We also have a blood glucose log that's smaller so you can carry it with you .
Who Should Check?
Talk to your doctor about whether you should be checking your blood glucose. People that may benefit from checking blood glucose include those:
taking insulin
that are pregnant
having a hard time controlling blood glucose levels
having low blood glucose levels
having low blood glucose levels without the usual warning signs
have ketones from high blood glucose levels
How Do I Check?
After washing your hands, insert a test strip into your meter.
Use your lancing device on the side of your fingertip to get a drop of blood.
Touch and hold the edge of the test strip to the drop of blood, and wait for the result.
Your blood glucose level will appear on the meter's display.
Note: All meters are slightly different, so always refer to your user's manual for specific instructions.
Other tips for checking:
With some meters, you can also use your forearm, thigh or fleshy part of your hand.
There are spring-loaded lancing devices that make sticking yourself less painful.
If you use your fingertip, stick the side of your fingertip by your fingernail to avoid having sore spots on the frequently used part of your finger.
What Are the Target Ranges?
Blood glucose targets are individualized based on:
duration of diabetes
age/life expectancy
comorbid conditions
known CVD or advanced microvascular complications
hypoglycemia unawareness
individual patient considerations.
The American Diabetes Association suggests the following targets for most nonpregnant adults with diabetes. More or less stringent glycemic goals may be appropriate for each individual.
A1C: 7%A1C may also be reported as eAG: 154 mg/dl
Before a meal (preprandial plasma glucose):&80&130 mg/dl
1-2 hours after beginning of the meal (Postprandial plasma glucose)*: Less than 180 mg/dl
*Postprandial glucose may be targeted
despite reaching preprandial glucose goals.
What Do My Results Mean?
When you finish the blood glucose check, write down your results and review them to see how food, activity and stress affect your blood glucose. Take a close look at your blood glucose record to see if your level is too high or too low several days in a row at about the same time. If the same thing keeps happening, it might be time to change your plan. Work with your doctor or diabetes educator to learn what your results mean for you. This takes time. Ask your doctor or nurse if you should report results out of a certain range at once by phone.
Keep in mind that blood glucose results often trigger . Blood glucose numbers can leave you upset, confused, frustrated, angry, or down. It's easy to use the numbers to judge yourself. Remind yourself that your blood glucose level is a way to track how well your diabetes care plan is working. It is not a judgment of you as a person. The results may show you need a change in your diabetes plan.
What About Urine Checks for Glucose?
Urine checks for glucose are not as accurate as blood glucose checks and should only be used when blood testing is impossible. Urine checks for ketones, however, is important when your diabetes is out of control or when you are sick. Everyone with diabetes should know how to .
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Last Reviewed: March&3,&2015
Last Edited: August&4,&2016
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More from diabetes.orgFrom Wikipedia, the free encyclopedia
This article needs additional citations for . Please help
by . Unsourced material may be challenged and removed. (November 2010) ()
Four generations of blood glucose meter, c. . Sample sizes vary from 30 to 0.3 μl. Test times vary from 5 seconds to 2 minutes (modern meters typically provide results in 5 seconds).
A glucose meter (or glucometer) is a
for determining the approximate concentration of
in the . It can also be a strip of glucose paper dipped into a substance and measured to the glucose chart. It is a key element of home
(HBGM) by people with
or . A small drop of blood, obtained by pricking the skin with a , is placed on a disposable test strip that the meter reads and uses to calculate the blood glucose level. The meter then displays the level in units of
Since approximately 1980, a primary goal of the management of
has been achieving closer-to-normal levels of glucose in the blood for as much of the time as possible, guided by HBGM several times a day. The benefits include a reduction in the occurrence rate and severity of
as well as a reduction in the short-term, potentially life-threatening complications of .
Leland C. Clark Jr. (1918– 2005) presented his first paper about the oxygen electrode, later named the Clark electrode, on 15 April 1956, at a meeting of the American Society for Artificial Organs during the annual meetings of the Federated Societies for Experimental Biology. In 1962, Clark and Ann Lyons from the Cincinnati Children’s Hospital developed the first glucose enzyme electrode. This biosensor was based on a thin layer of glucose oxidase (GOx) on an oxygen electrode. Thus, the readout was the amount of oxygen consumed by GOx during the enzymatic reaction with the substrate glucose. This publication became one of the most often cited papers in life sciences. Due to this work he is considered the “father of biosensors,” especially with respect to the glucose sensing for diabetes patients.
CDC image showing the usage of a lancet and a blood glucose meter.
Another early glucose meter was the Ames Reflectance Meter by Anton H. Clemens. It was used in American hospitals in the 1970s. A moving needle indicated the blood glucose after about a minute.
Home glucose monitoring was demonstrated to improve
of type 1 diabetes in the late 1970s, and the first meters were marketed for home use around 1981. The two models initially dominant in North America in the 1980s were the Glucometer, introduced on
is owned by
meter (by ). Consequently, these
names have become
to many health care professionals. In , a health care professional or a patient may refer to "taking a BM": "Mrs X's BM is 5", etc. BM stands for , now part of Roche, who produce test strips called 'BM-test' for use in a meter.
In North America,
resisted adoption of meter glucose measurements for inpatient diabetes care for over a decade. Managers of
argued that the superior accuracy of a laboratory glucose measurement outweighed the advantage of immediate availability and made meter glucose measurements unacceptable for inpatient diabetes management. Patients with diabetes and their
eventually persuaded acceptance. Some health care policymakers still resist the idea that the society would be well advised to pay the consumables (reagents, lancets, etc.) needed.
Home glucose testing was adopted for
more slowly than for type 1, and a large proportion of people with type 2 diabetes have never been instructed in home glucose testing. This has mainly come about because health authorities are reluctant to bear the cost of the test strips and lancets.
Test strips that changed color and could be read visually, without a meter, have been widely used since the 1980s. They had the added advantage that they could be cut longitudinally to save money. Critics argued that test strips read by eye are not as accurate or convenient as meter testing. The manufacturer cited studies that show the product is just as effective despite not giving an answer to one decimal place, something they argue is unnecessary for control of blood sugar. This debate also happened in Germany where "Glucoflex-R" was an established strip for type 2 diabetes. As meter accuracy and insurance coverage improved, they lost popularity.
"Glucoflex-R" is Australia manufacturer National Diagnostic Products alternative to the BM test strip. It has versions that can be used either in a meter or read visually. It is also marketed under the brand name Betachek. On May 1, 2009, the UK distributor Ambe Medical Group reduced the price of their "Glucoflex-R" test strip to the , by approximately 50%. This was expected to allow the NHS to save money on strips and perhaps loosen the restrictions on supply a little. Another low cost visually read strip is soon to be available on prescription according to sources at the NHS.[]
Special glucose meters for multi-patient hospital use are now used. These provide more elaborate quality control records. Their data handling capabilities are designed to transfer glucose results into
computer systems for billing purposes.
Illustration depicting glucose monitoring with glucometer.
Illustration depicting glucose meter and test strips.
This section needs additional citations for . Please help
by . Unsourced material may be challenged and removed. (November 2010) ()
There are several key characteristics of glucose meters which may differ from model to model:
Size: The average size is now approximately the size of the palm of the hand, although hospital meters can be the size of a . They are -powered.
Test strips: A consumable element containing chemicals that react with glucose in the drop of blood is used for each measurement. For some models this element is a plastic test strip with a small spot impregnated with
and other components. Each strip is used once and then discarded. Instead of strips, some models use discs, drums, or cartridges that contain the consumable material for multiple tests.
Coding: Since test strips may vary from batch to batch, some models require the user to manually enter in a code found on the vial of test strips or on a chip that comes with the test strip. By entering the coding or chip into the glucose meter, the meter will be calibrated to that batch of test strips. However, if this process is carried out incorrectly, the meter reading can be up to 4 mmol/L (72 mg/dL) inaccurate. The implications of an incorrectly coded meter can be serious for patients actively managing their diabetes. This may place patients at increased risk of hypoglycemia. Alternatively, some test strips contain the code info others have a microchip in the vial of strips that can be inserted into the meter. These last two methods reduce the possibility of user error.
has standardized their test strips around a single code number, so that, once set, there is no need to further change the code in their older meters, and in some of their newer meters, there is no way to change the code.
Volume of blood sample: The size of the drop of blood needed by different models varies from 0.3 to 1 μl. (Older models required larger blood samples, usually defined as a "hanging drop" from the fingertip.) Smaller volume requirements reduce the frequency of unproductive pricks.
Alternative site testing: Smaller drop volumes have enabled "alternate site testing" — pricking the forearms or other less sensitive areas instead of the midd pricking the sides of the fingertips is actually the least uncomfortable method of testing. Although less uncomfortable, readings obtained from forearm blood lag behind fingertip blood in reflecting rapidly changing glucose levels in the rest of the body.
Testing times: The times it takes to read a test strip may range from 3 to 60 seconds for different models.
Display: The glucose value in mg/dl or mmol/l is displayed on a digital display. The preferred measurement unit varies by country: mg/dl are preferred in the U.S., France, Japan, Israel, and India. mmol/l are used in Canada, Australia, China and the UK. Germany is the only country where medical professionals routinely operate in both units of measure. (To convert mmol/l to mg/dl, multiply by 18. To convert mg/dl to mmol/l, divide by 18.) Many meters can display ei there have been a couple of published instances[] in which someone with diabetes has been misled into the wrong action by assuming that a reading in mmol/l was really a very low reading in mg/dl, or the converse. In general, if a value is presented with a decimal point, it is in mmol/l, without a decimal it is most likely mg/dl.
Table of blood glucose units of measurement by country
Unit of measurement
Unit of measurement
Glucose vs. plasma glucose: Glucose levels in plasma (one of the components of blood) are generally 10%–15% higher than glucose measurements in whole blood (and even more after eating). This is important because home blood glucose meters measure the glucose in whole blood while most lab tests measure the glucose in plasma. Currently, there are many meters on the market that give results as "plasma equivalent," even though they are measuring whole blood glucose. The plasma equivalent is calculated from the whole blood glucose reading using an equation built into the glucose meter. This allows patients to easily compare their glucose measurements in a lab test and at home. It is important for patients and their health care providers to know whether the meter gives its results as "whole blood equivalent" or "plasma equivalent." One model measures
in the blood to detect ketoacidosis ().
Clock/memory: Most meters now include a clock that is set by the user for date and time and a memory for past test results. The memory is an important aspect of diabetes care, as it enables the person with diabetes to keep a record of management and look for trends and patterns in blood glucose levels over days and weeks. Most memory chips can display an average of recent glucose readings. A known deficiency of all current meters is that the clock is often not set to the correct time (i.e. - due to time changes, static electricity, etc...) and therefore has the potential to misrepresent the time of the past test results making pattern management difficult.
Data transfer: Many meters now have more sophisticated data handling capabilities. Many can be downloaded by a cable or infrared to a computer that has
to display the test results. Some meters allow entry of additional data throughout the day, such as
dose, amounts of
eaten, or exercise. A number of meters have been combined with other devices, such as insulin injection devices, , cellular transmitters
and . A radio link to an
allows automatic transfer of glucose readings to a calculator that assists the wearer in deciding on an appropriate insulin dose.
The cost of home blood glucose monitoring can be substantial due to the cost of the test strips. In 2006, the consumer cost of each glucose strip ranged from about $0.35 to $1.00. Manufacturers often provide meters at no cost to induce use of the profitable test strips. Type 1 diabetics may test as often as 4 to 10 times a day due to the dynamics of insulin adjustment, whereas type 2 typically test less frequently, especially when insulin is not part of treatment.
Batches of
test strips for some meters have been identified, which have been shown to produce inaccurate results.
Main article:
The search for a successful technique began about 1975 and has continued to the present without a clinically or commercially viable product. As of 1999, only one such product had ever been approved for sale by the FDA, based on a technique for electrically pulling glucose through intact skin, and it was withdrawn after a short time owing to poor performance and occasional damage to the skin of users.
Blood glucose meter. The sensor and transmitter are fixed to the upper arm. The reader shows days to replacement of sensor, current blood glucose level and a diagram of the latest blood glucose levels.
Continuous glucose monitor systems can consist of a disposable sensor placed under the skin, a transmitter connected to the sensor and a reader that receives and displays the measurements. The sensor can be used for several days before it needs to be replaced. The devices provide real-time measurements, and reduce the need for fingerprick testing of glucose levels. A drawback is that the meters are not as accurate because the read the glucose levels in the
which lags behind the levels in the blood.
Accuracy of glucose meters is a common topic of clinical concern. Blood glucose meters must meet accuracy standards set by the
(ISO). According to ISO 15197 Blood glucose meters must provide results that are within 20% of a laboratory standard 95% of the time (for concentrations about 75 mg/dL, absolute levels are used for lower concentrations). However, a variety of factors can affect the accuracy of a test. Factors affecting accuracy of various meters include calibration of meter, , pressure use to wipe off strip (if applicable), size and quality of blood sample, high levels of certain substances (such as ) in blood, , dirt on meter, , and aging of test strips. Models vary in their susceptibility to these factors and in their ability to prevent or warn of inaccurate results with error messages. The
has been a common way of analyzing and displaying accuracy of readings related to management consequences. More recently an improved version of the Clarke Error Grid has come into use: It is known as the . Older blood glucose meters often need to be "coded" with the lot of test strips used, otherwise, the accuracy of the blood glucose meter may be compromised due to lack of calibration.
One noninvasive glucose meter has been approved by the U.S. FDA: The GlucoWatch G2 Biographer made by . The device was designed to be worn on the wrist and used electric fields to draw out body fluid for testing. The device did not replace conventional blood glucose monitoring. One limitation was that the GlucoWatch was not able to cope with perspiration at the measurement site. Sweat must be allowed to dry before measurement can resume. Due to this limitation and others, the product is no longer on the market.
The market introduction of noninvasive blood glucose measurement by spectroscopic measurement methods, in the field of near-infrared (NIR), by extracorporal measuring devices, has not been successful because the devices measure tissue sugar in body tissues and not the blood sugar in blood fluid. To determine blood glucose, the measuring beam of infrared light, for example, has to penetrate the tissue for measurement of blood glucose.
There are currently three CGMS (continuous glucose monitoring system) available. The first is Medtronic's
RTS with a sub-cutaneous probe attached to a small transmitter (roughly the size of a quarter) that sends interstitial glucose levels to a small pager sized receiver every five minutes. The Dexcom System is another system, available in two different generations in the US, the G4 and the G5. (1Q 2016). It is a
probe with a small transmitter. The receiver is about the size of a cell phone and can operate up to twenty feet from the transmitter. The Dexcom G4 transmits via radio frequency and requires a dedicated receiver. The G5 version utilizes Bluetooth low energy for data transmission, and can transmit data directly to a compatible cellular telephone. Currently, only Apple's iPhone can be used as a receiver, but Dexcom is in the process of getting an Android version approved, and anticipates availability in the second half of 2016. Aside from a two-hour calibration period, monitoring is logged at five-minute intervals for up to 1 week. The user can set the high and low glucose alarms. The third CGMS available is the FreeStyle Navigator from Abbott Laboratories.
There is currently an effort to develop an integrated treatment system with a glucose meter, , and
controller, as well as an effort to integrate the glucose meter and a cell phone. These glucose meter/cellular phone combinations are under testing and currently cost $149 USD retail.[] Testing strips are proprietary and available only through the manufacturer (no insurance availability). These "Glugophones" are currently offered in three forms: as a dongle for the , an add-on pack for
model UX5000, VX5200, and LX350 cell phones, as well as an add-on pack for the
Razr cell phone. In US, this limits providers to
and . Similar systems have been tested for a longer time in Finland.[]
Recent advances in cellular data communications technology have enabled the development of glucose meters that directly integrate cellular data transmission capability, enabling the user to both transmit glucose data to the medical caregiver and receive direct guidance from the caregiver on the screen of the glucose meter. The first such device, from Telcare, Inc., was exhibited at the 2010 CTIA International Wireless Expo, where it won an E-Tech award. This device is currently undergoing clinical testing in the US and internationally.
In early 2014
reported testing prototypes of
that monitor glucose levels and alert users when glucose levels cross certain thresholds.
two used Accu-chek test strips for their blood glucose test system for diabetics. The lower one has had the cover peeled off to show the circuit
Many glucose meters employ the oxidation of glucose to
catalyzed by
(sometimes known as GOx). Others use a similar reaction catalysed instead by another ,
(GDH). This has the advantage of sensitivity over glucose oxidase but is more susceptible to interfering reactions with other substances.
The first-generation devices relied on the same
reaction that is still used nowadays in glucose test strips for urine. Besides glucose oxidase, the test kit contains a
derivative, which is oxidized to a blue polymer by the
formed in the oxidation reaction. The disadvantage of this method was that the test strip had to be developed after a precise interval (the blood had to be washed away), and the meter needed to be calibrated frequently.
Most glucometers today use an electrochemical method. Test strips contain a capillary that sucks up a reproducible amount of blood. The glucose in the blood reacts with an enzyme electrode containing glucose oxidase (or dehydrogenase). The enzyme is reoxidized with an excess of a mediator reagent, such as a
ion, a ferrocene derivative or osmium bipyridyl complex. The mediator in turn is reoxidized by reaction at the electrode,which generates an electric current. The total charge passing through the electrode is proportional to the amount of glucose in the blood that has reacted with the enzyme. The
method is a technique where the total amount of charge generated by the glucose oxidation reaction is measured over a period of time. This is analogous to throwing a ball and measuring the distance it has covered so as to determine how hard it was thrown. The amperometric method is used by some meters and measures the electric current generated at a specific point in time by the glucose reaction. This is analogous to throwing a ball and using the speed at which it is travelling at a point in time to estimate how hard it was thrown. The coulometric method can allow for variable test times, whereas the test time on a meter using the amperometric method is always fixed. Both methods give an estimation of the concentration of glucose in the initial blood sample.
The same principle is used in test strips that have been commercialized for the detection of diabetic ketoacidosis (DKA). These test strips use a beta-hydroxybutyrate-dehydrogenase enzyme instead of a glucose oxidizing enzyme and have been used to detect and help treat some of the complications that can result from prolonged .
Blood alcohol sensors using the same approach, but with alcohol dehydrogenase enzymes, have been tried and patented but have not yet been successfully commercially developed.
Although the apparent value of immediate measurement of blood glucose might seem to be higher for
than , meters have been less useful. The primary problems are precision and ratio of false positive and negative results. An imprecision of ±15% is less of a problem for high glucose levels than low. There is little difference in the management of a glucose of 200 mg/dl compared with 260 (i.e., a "true" glucose of 230±15%), but a ±15% error margin at a low glucose concentration brings greater ambiguity with regards to glucose management.
The imprecision is compounded by the relative likelihoods of false positives and negatives in populations with diabetes and those without. People with type 1 diabetes usually have glucose levels above normal, often ranging from 40 to 500 mg/dl (2.2 to 28 mmol/l), and when a meter reading of 50 or 70 (2.8 or 3.9 mmol/l) is accompanied by their usual hypoglycemic symptoms, there is little uncertainty about the reading representing a "true positive" and little harm done if it is a "false positive." However, the incidence of hypoglycemia unawareness, hypoglycemia-associated autonomic failure (HAAF) and faulty counterregulatory response to hypoglycemia make the need for greater reliability at low levels particularly urgent in patients with type 1 diabetes mellitus, while this is seldom an issue in the more common form of the disease, type 2 diabetes mellitus.
In contrast, people who do not have diabetes may periodically have hypoglycemic symptoms but may also have a much higher rate of false positives to true, and a meter is not accurate enough to base a diagnosis of hypoglycemia upon. A meter can occasionally be useful in the monitoring of severe types of hypoglycemia (e.g., ) to ensure that the average glucose when fasting remains above 70 mg/dl (3.9 mmol/l).
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