Prickless Glucose Monitoring - Monitoring Your Blood Sugar Levels: Diabetes

Content provided by the Faculty of the Harvard Medical School

"Prickless" glucose monitoring

Because traditional blood glucose monitoring requires considerable effort, many people with diabetes test themselves less frequently than recommended. But several new devices may encourage people, particularly those who dislike taking blood samples, to test themselves more often. Although FDA-approved only for certain people, these devices provide a glimpse into the future of less-invasive glucose monitoring, when testing will be effortless, automatic, and continuous (see "Continuous glucose monitoring,"). Another device, the Lasette, substitutes laser energy to pierce the skin and obtain a blood sample.

GlucoWatch Biographer

One of the newest methods for monitoring glucose uses a gadget that James Bond would love. The GlucoWatch Biographer, available only by prescription, is a wristwatch-like device that has sensors on its underside. In 2001, the GlucoWatch Biographer became the first automatic, noninvasive blood sugar monitor approved by the FDA. In 2002, a second-generation device, the GlucoWatch G2 Biographer, was approved for use by adults and children over age six.

Photo courtesy of Cygnus, Inc. The GlucoWatch Biographer uses sensors on its underside to monitor blood sugar levels.

The device applies a very low electric current to extract fluid samples from the skin every 10 minutes for 13 hours, even during sleep. The device stores the readings and sounds an alarm if your blood sugar reaches a preset level.

Because it provides frequent readings, the GlucoWatch Biographer offers a comprehensive look at blood sugar levels over the course of the day, helping people with diabetes detect patterns and trends. For instance, someone using the device can get up to 78 readings in a 13-hour period, while he or she may take just one or two readings in the same time frame using the finger-prick method.

FDA approval of the device followed clinical trials that compared GlucoWatch Biographer readings with traditional finger-prick blood glucose tests and found the measurements fairly consistent. However, up to a quarter of the time, its results were off by more than 30%. It had more trouble detecting very low glucose levels than very high ones. It wasn't accurate if the patient's arm was too sweaty — a concern because perspiration is common with hypoglycemia. Finally, it can cause some degree of skin irritation in up to half of the people who use it.

Because it's sometimes inaccurate, the GlucoWatch Biographer shouldn't replace finger-prick blood tests. Instead, use a traditional glucose monitor to confirm any result that triggers an alarm and before making any treatment decisions.

MiniMed Continuous Glucose Monitoring System

This device uses a sensor implanted just under the skin in the abdomen to record glucose levels continuously for up to three days. A physician can then review the glucose profile and determine how sugar levels fluctuated in response to diet and activity levels and medications.

Currently the device is available only by prescription, and a doctor needs to download and interpret the data on glucose fluctuations. As such, it is a helpful tool for a doctor to have so he or she can adjust your treatment, if necessary. Eventually, the technology may improve so that patients can print glucose readings on demand and make their own adjustments in diet or medications — but that is not yet possible with the current device.

Lasette

The Lasette doesn't eliminate the need for a glucose meter, but it does enable you to get the blood sample without using a lancet. This device uses a tiny laser beam to perforate your finger, so drawing blood is nearly painless. Although more comfortable than traditional testing methods, it's expensive (about $1,000). And because it literally burns through your skin, the Lasette causes a distinct odor.

Photo courtesy of Cell Robotics International, Inc. The Lasette uses a tiny laser beam to draw a blood sample.

Doing your research

Ask your insurance company what supplies it covers. Medicare, for example, reimburses people for the cost of one meter a year and glucose testing supplies, with the number of strips determined by whether you use insulin. A good resource is the American Diabetes Association's "Annual Resource Guide for Diabetes Supplies" (see "Resources").

No matter what equipment you choose, your medical team will explain how to use it properly and how to keep a log of blood glucose readings, insulin shots, and food intake. By keeping a daily record of your blood tests, you can tell how well you're managing your diabetes and, with the advice of your health care team, can make adjustments in your treatment plan.

Last updated:	January 23, 2007