Non-invasive Blood Glucose Monitoring
Edition: June 2003 - Vol 11 Number 06
For diabetics, there?s no getting around blood glucose monitoring. Particularly for those with type 2 diabetes, three or four daily blood tests may be necessary ? perhaps even more when there have been changes in diet, medication or exercise routines.
On one hand, the tried-and-true methods of self-blood-glucose monitoring ? where the patient must prick his or her finger to extract a drop of blood ? remain the gold standard. In these tests, the blood is applied to a test strip containing glucose-sensitive chemicals. The blood sample is analyzed using a glucometer. In spite of the accuracy of these tests, the soreness incurred from pricking one?s finger several times each day may deter some from self-monitoring their blood glucose levels regularly enough.
In response to this dilemma, researchers have been working to produce noninvasive tests to supplement ? not replace ? current methods. Noninvasive methods that have been explored in recent years, according to the National Diabetes Information Clearinghouse, include:
? Shining infrared light through the forearm or finger.
? Using low-level electrical currents to draw glucose from the blood up through the skin.
? Measuring glucose levels in saliva or blood.
Through the Skin
Cygnus Inc., of Redwood City, Calif., received FDA approval in March 2002 for its GlucoWatch G2 Biographer, which employs low-level electric currents to extract glucose through the skin. Available by prescription, the product also has received supplemental pre-market approval for use by children and adolescents between 7 and 17 years, according to Cygnus. The company is careful to explain that the GlucoWatch G2 Biographer is designed for use in conjunction with ?finger-stick? methods of blood glucose testing.
The system includes two parts. The Biographer is worn as ? and looks like ? a watch. Its function is to calculate, display and store glucose readings, notes Cygnus. The AutoSensor is a single-use component designed to collect and convert the glucose into an electrical signal. The AutoSensor fits into the back of the unit and adheres to the patient?s skin.
The system reportedly measures glucose levels as frequently as every 10 minutes for up to 13 hours. It stores as many as 8,500 glucose levels, aiding in the detection of glucose level trends and patterns. When glucose readings are too low, an alarm warns the user.
Products in Development
Among the different non-invasive ? or minimally invasive ? technologies currently being developed is the continuous glucose-monitoring patch by Norcross, Ga.-based SpectRx. Designed for wear on top of the skin, the system measures glucose levels in interstitial fluid (ISF) ? the clear fluid beneath the skin through which glucose and other nutrients travel from the bloodstream to the cells. ISF glucose levels are comparable to blood glucose levels, according to SpectRx.
The SpectRx system employs a hand-held laser to produce an array of micropores in the outer layer of skin. A continuous stream of ISF is drawn into the patch and to the glucose sensor. The system?s technology, which reportedly is pain-free, can be used both for continuous and single-use monitoring.
Infratec Inc., of Wilton, Conn., has been testing a new system ? a portable device the size of a cell phone, designed to measure blood glucose levels when inserted in the ear. The device is placed in the patient?s ear for about 10 seconds, during which time it isolates and measures blood glucose levels using the body?s natural heat or thermal radiation, according to Infratec. The technology differs somewhat from others that rely on thermal energy emission: This system relies on a mid-infrared range of thermal energy, whereas other systems have attempted to measure glucose levels in a near-infrared energy range.
Minimally Invasive Option
The growth of diabetes has contributed to a worldwide market for glucose testing of nearly $3.7 billion and is growing at an annual rate of 12 percent to 18 percent, according to SpectRx. While distributor reps watch as the market continues to produce more sophisticated solutions for blood glucose testing, they may be interested in some minimally invasive options that exist right now. For example, Cell Robotics International offers the Lassette Plus, a needle-free laser device that is said to produce less pain and reduce soreness and trauma for patients.
Because the system doesn?t require needles, it helps physicians comply with Needlestick Safety and Prevention regulations and reduces liability issues. The Lassette Plus is FDA-cleared for adults and children over 5 years old. The system
produces a small hole in the skin by vaporizing water rather than tearing the skin with a lancet, thereby protecting capillary vessels. The patient can self-test at home. Basically, he or she must select an appropriate power level; turn on the device and press the charge/discharge button; position his or her finger; and press a button to fire the laser. The patient can use a glucometer to test the blood, just as with traditional home methods.
Without proper management, diabetes can lead to a number of long-term debilitating illnesses, including kidney and heart disease, nerve damage and blindness. Complications resulting from uncontrolled diabetes have contributed to annual medical costs as high as $100,000 billion, according to Cygnus. Frequent glucose monitoring, along with proper insulin treatment, can permit more diabetics to lead healthier lives.