Glucose Meter for Diabetes Testing, how they work
A glucose meter (or glucometer ) is a medical product or device for determining
the approx. concentration of glucose in the blood stream. It is a key element of
home blood glucose monitoring or metering (HBGM) by people with diabetes or
hypoglycemia. A small drop of blood, obtained by penetrating the skin with a
lancet, is placed on a disposable test strip that the meter reads and uses to
calculate the bloods glucose level. The meter then displays the
glucose level.
Many glucose meters employ the oxidizing of glucose
into gluconolactone which
is catalyzed by glucose oxidase. Others use a similar reaction catalysed instead
by another enzyme, glucose dehydrogenase. This has the advantage of sensitivity
over glucose oxidase but is more susceptible to interfering reactions with other
substances.
|
Glucose Meters are commonly called glucometers
Most glucometers today use an electrochemical method for determination. 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.
The enzyme is reoxidized with an excess of a mediator reagant, such as a
ferricyanide ion, or osmium bipyridyl complex. The mediator in turn is
reoxidised by reaction at the electrode,which generates an electrical current.
The total charge passing through the electrode is proportional to the amount of
glucose in the blood that has reacted with the enzyme and metered appropriately.
The first-generation devices relied on the same colorimetric reaction that is
still used nowadays in glucose test strips for urine. Besides glucose oxidase,
the test kit contains a benzidine derivative, which is oxidized to a blue
polymer by the hydrogen peroxide formed in the oxidation reaction. The
disadvantage of this method was that the test strip had to be developed after a
precise interval, and the meters needed to be calibrated frequently.
|
