It is important in the care of diabetes mellitus. A blood glucose test is performed by piercing the skin (typically, on the finger tip) to draw blood, then placing the blood on a chemically active disposable strip which indicates the result either by changing colour, or changing an electrical characteristic, the latter being measured by an electronic meter.
Most people with Type 2 diabetes test at least once per day (usually before breakfast) to assess the effectiveness of their diet and exercise. Many people with Type 2 use an oral medication to combat their insulin resistance, and test their blood glucose before and after breakfast to assess the effectiveness of their dosage. Diabetics who use insulin (all Type 1 diabetes and many Type 2s) usually test their blood sugar more often (3 to 10 times per day), both to assess the effectiveness of their prior insulin dose and to help determine their next insulin dose.
Improved technology for measuring blood glucose is rapidly changing the standards of care for all diabetic people. There are several methods of blood glucose testing currently available.
Chemical test strips are a medium cost method for monitoring blood glucose. A fairly large drop of blood, usually taken from the fingertip, is placed on a chemically prepared strip, called a blood glucose testing strip. The chemicals in the strip react with the blood, changing color according the concentration of glucose, which can then be read by comparing the color with a chart on the side of the test strip container.
These are recommended only for people who are occasionally monitoring their blood glucose level (prediabetic or type 2) and are not using insulin. They are useful for people who can't afford to use an electronic meter, and for people who dislike electronic meters.
A blood glucose meter is an electronic device for measuring the blood glucose level. A relatively small drop of blood is placed on a disposable test strip which interfaces with a digital meter. Within several seconds, the level of blood glucose will be shown on the digital display.
While more expensive, blood glucose meters seem a breakthrough in diabetes self care. As the drops of blood needed for the meter become smaller, the pain associated with testing is reduced and the compliance of diabetic people to their testing regimens is improved. Although the cost of using blood glucose meters seems high, it is believed to be a cost benefit relative to the avoided medical costs of the complications of diabetes.
A recent and welcome advance is the use of small blood drops for blood glucose testing from other places than the finger tips. This alternate site testing uses the same test strips and meter, is practically pain free, and gives the real estate on the finger tips a needed break if they become sore. The disadvantage of this technique is that there is usually less blood flow to alternate sites, which prevents the reading from being accurate when the blood sugar level is changing.
One company has developed automatic self-coding meters.
Continuous blood glucose monitors measure the glucose level of interstitial fluid. Shortcomings of CGM systems due to this fact are:
Patients therefore require traditional fingerstick measurements for calibration (typically twice per day) and are often advised to use fingerstick measurements to confirm hypo- or hyperglycemia before taking corrective action.
The lag time discussed above has been reported to be about 5 minutes. Anecdotally, some users of the various systems report lag times of up to 10-15 minutes. This lag time is insignificant when blood sugar levels are relatively consistent. However, blood sugar levels, when changing rapidly, may read in the normal range on a CGM system while in reality the patient is already experiencing symptoms of an out-of-range blood glucose value and may require treatment. Patients using CGM are therefore advised to consider both the absolute value of the blood glucose level given by the system as well as any trend in the blood glucose levels. For example, a patient using CGM with a blood glucose of 100 mg/dl on their CGM system might take no action if their blood glucose has been consistent for several readings, while a patient with the same blood glucose level but whose blood glucose has been dropping steeply in a short period of time might be advised to perform a fingerstick test to check for hypoglycemia.
Continuous monitoring allows examination of how the blood glucose level reacts to insulin, exercise, food, and other factors. The additional data can be useful for setting correct insulin dosing ratios for food intake and correction of hyperglycemia. Monitoring during periods when blood glucose levels are not typically checked (e.g. overnight) can help to identify problems in insulin dosing (such as basal levels for insulin pump users or long-acting insulin levels for patients taking injections). Monitors may also be equipped with alarms to alert patients of hyperglycemia or hypoglycemia so that a patient can take corrective action(s) (after fingerstick testing, if necessary) even in cases where they do not feel symptoms of either condition. While the technology has its limitations, studies have demonstrated that patients with continuous sensors experience less hyperglycemia and also reduce their glycosylated hemoglobin levels.
Currently, continuous blood glucose monitoring is not automatically covered by health insurance in the United States in the same way that most other diabetic supplies are covered (e.g. standard glucose testing supplies, insulin, and even insulin pumps). However, an increasing number of insurance companies do cover continuous glucose monitoring supplies (both the receiver and disposable sensors) on a case-by-case basis if the patient and doctor show a specific need. The lack of insurance coverage is exacerbated by the fact that disposable sensors must be frequently replaced (sensors by Dexcom and Minimed have been FDA approved for 7- and 3-day use, respectively, though some patients wear sensors for longer than the recommended period) and the receiving meters likewise have finite lifetimes (less than 2 years and as little as 6 months). This is one factor in the slow uptake in the use of sensors that have been marketed in the United States.
Some current and future continuous glucose monitoring products include:
This technology is an important component in the effort to develop a closed-loop system connecting real-time automatic control of an insulin pump based on immediate blood glucose data from the sensor. One important goal is to develop an algorithm for automatic control, by which the system would function as an artificial pancreas. However, this is a long-term goal at this point for companies that manufacture such systems, as such an algorithm would need to be very complex in order to accurately control blood sugar levels without any user input.
Products under development include:
Most of the non-invasive methods under development are continuous glucose monitoring methods and offer the advantage of providing additional information to the subject between the conventional finger stick, blood glucose measurements and over time periods where no finger stick measurements are available (i.e. while the subject is sleeping). Products under development include:
The National Institute for Health and Clinical Excellence (NICE), UK released updated diabetes recommendations on the 30th May 2008, which recommend that self-monitoring of plasma glucose levels for people with newly diagnosed type 2 diabetes must be integrated into a structured self-management education process.
There haven't been any studies investigating the long term damage caused by continual body piercing.
Blood glucose self-monitoring in type 1 and type 2 diabetes: reaching a multidisciplinary consensus.(Consensus)
Jun 22, 2004; Introduction In the light of evidence that emerged from the UKPDS (1998) and the DCCT (1993), individual patients must be made...