Self-Monitoring of Blood Glucose

It is imperative that people with both type 1 and type 2 diabetes have good glycemic control, which can be attained with appropriate drug and self-monitoring of blood glucose. The benefit of such glycemic control has been proven in rigorous trials. Self-monitoring of blood glucose is done by a diabetic using a home glucose meter to check and track his/ her blood sugar levels. Checking blood sugar levels on a day-to-day basis can greatly improve diabetes control.

Blood glucose monitoring meters can measure blood sugar quickly and easily. Apart from health care providers and pharmacists, it is also important for patients of diabetes to know how to choose the best meter, based on the available meter technologies and features.

Technology involved

There are more than 20 different meters that vary in size, shape, test time, and memory features. You can choose based on your own preferences and needs. The two basic technologies employed in home blood glucose meters are reflectance photometry and biosensor (electrochemical) technology. Although the type of technology is one factor that contributes to the overall performance of blood glucose meters, other factors to be considered are the performance of both the operator and the test strips

Color reflectance photometry: This is first-generation blood glucose meter technology. In this technique, an enzyme catalyzes oxidation of the blood glucose within the test strip. The oxidized glucose reacts with chroma-gen, to produce a color change. This color change is proportional to the amount of glucose in the blood, and a numerical value is generated. Adequate lighting and suitable temperature, humidity, altitude etc. are necessary for accurate results to be obtained.

Care to be taken: The optic area of reflectance photometry meters need to be cleaned periodically with a cotton swab that has been moistened with water, so that the meter will produce accurate readings.

Biosensor technology: In glucose meters using this technology also, the blood undergoes oxidation, although this reaction is slightly different. An electrical charge is created, and this charge is directly proportional to the blood glucose content. The charge generated represents the concentration of glucose in the blood sample, and a numerical value is displayed. Amperometry and coulometry are the 2 types of biosensor (electrochemical) blood glucose testing methods.

Amperometric technology: In this method, only a small percentage of glucose is measured, which is then converted into a numerical value with the help of a multiplier. Therefore, blood glucose readings may be affected by environmental temperature, medications, and other factors. Besides, small samples may result in inaccurate readings because of a weak signal being generated.

Coulometry : In this technique, all the glucose in a blood sample is converted into an electrical current and is not affected by other medications or conditions the patient may have. Coulometry allows the patient to use the smallest sample size of any available technology.

Selection of device

With numerous blood glucose meters in the market, selecting the appropriate meter for a particular patient is a difficult task. Although most meters are comparable in performance, they do vary with regard to plasma versus whole blood calibration, testing site, meter size and shape, test time, sample size, memory capacity, software compatibility, complexity, and test strips. A health care provider can recommend specific features based on individual preferences. Most meters now require only a very small amount of blood, thereby reducing the pain involved in the process. Further, some meters can now use blood from your forearm or thigh instead of your fingertip. When selecting a meter, the following patient and meter characteristics need to be considered.

Poor Vision: Patients who have poor vision need to go for a meter with a large digital display and easy sample collection (preferably large strips).

Poor Manual Dexterity: For patients who have arthritis or problems with dexterity, manipulation of both the meter and the test strips can be an issue. Easy-to-use meters with a small sample size and test strips that do not require excessive manipulation should be recommended to make the testing process as easy as possible.

Children and/or Adults with Type 1 Diabetes: Appearance, portability, and small sample size are the factors to be taken into consideration for children with diabetes. Besides, children and adults with type 1 diabetes may benefit from monitors that record insulin doses, meals, snacks, and events.

Concurrent Disease States or Medications: Persons with sickle-cell disease, end-stage renal disease, or other conditions that alter hemoglobin level need to use a meter that is not affected by variations in hematocrit (The ratio of the volume occupied by packed red blood cells to the volume of the whole blood). Also, persons who take warfarin or other anticoagulant medications need to use a meter that requires a small sample so as to minimize the depth of puncture required to obtain a blood sample.

Portability: This factor is applicable to diabetics who have a active life style, so that they may be able to carry their gadgets wherever they go.

Downloadability: Now a days most glucose meters have compatible software for patients who are interested in downloading test results for the purpose of reviewing blood glucose trend or graph information. Software may be downloaded free of charge on most manufacturers' Web sites or may be purchased for use on personal computers and personal digital assistants. The data may be then sent via e-mail to the patients' physician/s so that they may be compiled into useful charts and/or diagrams.

Factors Affecting Blood Glucose Readings

There are several factors to consider when evaluating the results of a blood glucose measurement. Ensuring that the person using the meter is doing so correctly can minimize most of these factors. Diabetics need to be guided regarding:

• Preparing the meter
• Obtaining the blood sample
• Applying blood to the test strip
• Interpreting and recording results
• Disposal of test objects (sharps disposal)

Self-management of blood glucose is crucial as it allows patients to identify episodes of hypo- and hyper-glycemia as well as their daily responses to food and medications. With guidance from health care professionals, patients can use this information to adjust their diet, exercise, or medication regimen in order to minimize adverse diabetes-related outcomes and complications.