While a standard fingerstick test records a person’s glucose level as a snapshot in time, the STS-7 Continuous Glucose Monitoring System (STS-7 System) measures glucose levels every five minutes throughout a seven-day period. This additional information can be used to detect trends and track patterns in glucose levels throughout the week that wouldn’t be captured by fingerstick measurements alone. However, diabetics must still rely on the fingerstick test to decide whether additional insulin is needed.

“The STS-7 System supplements standard fingerstick meters and test strips, providing diabetics ages 18 and older with a way to see trends and track patterns,” said Daniel Schultz, M.D., director of FDA’s Center for Devices and Radiological Health. “It can help detect when glucose levels drop during the overnight hours, show when glucose levels rise between meals and suggest how exercise and diet might affect glucose levels.”

The STS-7 System, manufactured by DexCom Inc. of San Diego, Calif., uses a disposable sensor placed just below the skin in the abdomen to measure the level of glucose in the fluid found in the body’s tissues (interstitial fluid). Sensor placement causes minimal discomfort and can easily be done by patients themselves. The sensor must be replaced weekly. An alarm can be programmed to sound if a patient’s glucose level reaches pre-set lows or pre-set highs.

Diabetes is caused by the body’s inability to produce or use insulin, a hormone that unlocks the cells of the body, allowing glucose (sugar) to enter and fuel them.

An estimated 20.8 million people in the United States—7 percent of the population—have diabetes. Most have type 2 diabetes, a condition in which the body does not properly use insulin. An estimated 5 percent to 10 percent of people with this chronic disease have type 1 diabetes, which results from the body's failure to produce insulin. People with type 1 diabetes must take insulin every day.

Diabetes can lead to wide fluctuations in blood sugar levels. Over time, abnormally high levels of glucose can damage the small and large blood vessels, leading to diabetic blindness, kidney disease, amputations of limbs, stroke, and heart disease.

While there is no known cure, studies have shown that patients who regularly monitor and regulate their blood glucose levels have lower incidences of complications associated with the disease.

FDA’s approval of the STS-7 System was based on results of a study conducted by DexCom of 72 patients with diabetes at five clinical sites in the United States. The study demonstrated that the STS-7 System was safe and effective for detecting trends and tracking patterns in glucose levels in adults.

A three-day version of the device, the STS Continuous Glucose Monitoring System, was approved in March 2006.