Monitoring Tests

Monitoring Tests

Glucose (Blood Sugar) Levels

Both low blood sugar (hypoglycemia) and high blood sugar (hyperglycemia) are of concern for patients who take insulin. It is important, therefore, to carefully monitor blood glucose levels. In general, patients with type 1 diabetes need to take readings four or more times a day. Patients should aim for the following measurements:

• Pre-meal glucose levels of between 90 and 130 mg/dL
• Bedtime levels of between 110 and 150 mg/dL

Different goals may be required for specific individuals, including pregnant women, very old and very young people, and those with accompanying serious medical conditions.

Finger-Prick Test. A typical blood sugar test includes the following:

• A drop of blood is obtained by pricking the finger
• The blood is then applied to a chemically treated strip
• Monitors read and provide results

Home monitors are about 10 - 15% less accurate than laboratory monitors are and many do not meet the standards of the American Diabetes Association. Most doctors believe, however, that they are accurate enough to indicate when blood sugar is too low.

Some simple procedures may improve accuracy:

• Testing the meter once a month
• Recalibrating it whenever a new packet of strips is used
• Using fresh strips; outdated strips may not provide accurate results.
• Keeping the meter clean
• Periodically comparing the meter results with the results from a laboratory

Less Invasive or Noninvasive Tests. A number of noninvasive or less painful tests are on the market or under investigation. The following are some examples:

• A battery-powered wristwatch-like device (GlucoWatch) measures glucose by sending tiny electric currents through the skin -- a technique called reverse iontophoresis. It is painless and has a warning device when detecting high glucose levels. It takes 2 hours to warm up and the sensor pads need to be changed every day. About a quarter of the time, it differs significantly from actual fingerstick tests, however, so it should be used to supplement, not replace, blood tests. Nevertheless, in one study it was very effective in improving glucose control in children and was well tolerated. The device in the study also included an alarm that allowed detection of nighttime hypoglycemia. Refinements in the technique should improve accuracy.
• The continuous glucose monitoring system (Minimed) uses a needle-like sensor inserted under the skin, which is attached to a beeper-like computer device worn by the patient. Glucose is measured every 5 minutes, and the results are stored in the device. After 5 days, the patient removes the sensor and the doctor obtains data from the device, which is then used to identify trends and insulin needs. It is does not replace fingerstick tests.
• Some monitors, such as Sof-Tact and FreeStyle, are designed to obtain blood from areas of the skin that are less sensitive. Both appear to be less painful than standard methods.
• Investigative pain-free monitors include laser devices (Altea MicroPor), microneedles, and infrared devices.