Dual Sensor Could Provide More Information, Earlier Warning For Diabetics

In the laboratory, researchers created the electronic framework for a tiny sensor that could be implanted in the human body. The first device of its kind to measure the glucose-insulin ratio, it could help predict changes leading to high or low blood sugar levels, according to Joseph Wang, an author of the paper and professor at New Mexico State University in Las Cruces, N.M.

Tracking insulin levels along with glucose could identify trends and concentrations sooner than is now possible, Wang said. Earlier warning of trouble signs could help diabetics stave off fatigue and more serious complications such as kidney failure and heart disease, he continued.

Insulin is the hormone that allows glucose (blood sugar) to enter cells and convert foods into energy to sustain life. When insulin fails to "unlock" cells, glucose builds up in the blood and cells die. Hazardous conditions can occur when blood contains either too little or too much glucose.

Glucose sensors and insulin pumps have been used for nearly a decade to measure and remedy imbalances in blood sugar levels. The sensor detects excess glucose while the pump acts as an artificial pancreas - the organ that produces insulin in the body. Another device known as an insulin detector estimates the amount of the hormone in the blood.

Combining two types of sensors in such a small device was a complicated task, Wang said. Glucose is measured in the milli-molar range, while insulin is tracked on even smaller nano-molar levels - a fivefold difference in magnitude. In addition, each must send an electrical signal without interference to a minicomputer that, ideally, can calculate, store and display information, he added.

"The nice thing is that this is two different concepts," Wang said. "Despite the fact that they are completely different principles, we have found that they can be integrated and work independently."

Employing methods similar to those used to create existing implants, the researchers designed a needle-shaped sensor that can be implanted in the body where it won't cause problems. The next step is testing the device in animals. The researchers hope to halve the size of the sensor, reducing it to the thickness of 26-gauge wire (about the size of a hypodermic needle).

More than 15 million people in the United States have diabetes and approximately 800,000 are diagnosed with the disease each year, according to the American Diabetes Association. Nearly 95 percent of those have type 2, or adult-onset, diabetes in which the body does not make enough, or properly use insulin. The rest have type 1 diabetes, in which the body produces no insulin; this necessitates daily insulin shots. Both forms of the life-threatening disease can cause blindness, nerve degeneration and stroke.

The research cited above was funded by a research grant from the National Institutes of Health.

Joseph Wang, Ph.D., is a professor in the department of chemistry and biochemistry at New Mexico State University in Las Cruces, N.M.