FDA approval of the Guardian RT continuous glucose monitoring system bodes well for the regulatory success of an integrated insulin pump-glucose monitoring product, Medtronic says.

The Minneapolis firm announced approval of the monitoring system's PMA supplement application Aug. 10 for Type 1 and Type 2 diabetics over age 18.

Guardian RTemploys a small, disposable sensor inserted under the skin to record glucose levels every five minutes. Results are sent wirelessly to a pager-sized monitor, which has alarms to alert patients of dangerously high or low glucose levels.

The sensor, which measures glucose concentrations in the interstitial fluid between tissue cells, needs to be replaced every three days, according to Medtronic.

"Our next really big step is integrating an insulin pump," company spokesperson Deanne McLaughlin said. Medtronic is conducting clinical trials for its Paradigm sensor-augmented pump, which would work in conjunction with Guardian RT to allow patients to provide immediate insulin therapy in response to varying blood sugar levels.

The firm expects to submit a PMA for the sensor-augmented insulin pump this year. The firm will then begin a series of clinical trials under the rubric STAR (Sensor Augmented Therapy for A1c Reduction) to further evaluate the benefits of real-time glucose readings combined with insulin pump therapy.

The Guardian RT approval "is very good news" toward the goal of obtaining U.S. market approval for an integrated system, McLaughlin said. The firm's longer-term objective is to develop an implantable, closed loop monitor-pump artificial pancreas system, but that is further back in the pipeline, she noted.

Currently, Guardian RT is not approved for directly informing treatment decisions, "but rather to provide an indication of when a fingerstick may be required," according to FDA's ¹ approval order. The monitor needs to be calibrated twice a day with measurements from a standard glucose meter.

According to both FDA and Medtronic, the device is useful in helping physicians and patients track and analyze patterns in glucose concentrations during a patient's daily activities.

A1c testing, which measures average blood glucose levels over several months, and fingerstick glucose testing, which provides glucose levels at a single point in time, may not reveal the day-to-day blood sugar fluctuations that can cause many diabetes-related complications, according to Medtronic's website.

The RT model improves incrementally on the original Guardian continuous monitoring system, approved in January 2004. The original model, which was never marketed in the U.S., provides danger alarms but does not display real-time glucose values on a screen (² Also see "Guardian Approval Should Give Medtronic Sizable Lead In CGMS Market" - Medtech Insight, 16 February, 2004., p. 14).

Animas' GlucoWatch continuous monitoring system also is FDA-approved for measuring glucose in interstitial fluid drawn through the skin, but it does not eliminate the need for fingerstick testing. Animus is not actively marketing the device, which it acquired from Cygnus in December 2004 (³ Also see "Animas Maps Two-Pronged Strategy For Glucose Sensor Development" - Medtech Insight, 3 January, 2005., p. 5).

Abbott and DexCom are vying to be among the first firms to reach the market with continuous glucose monitoring systems - Freestyle Navigator and STS , respectively - that are labeled as replacements to fingerstick testing.

Medtronic plans a limited launch of the RT product in selected cities at the end of September. The firm will assess how it should approach training and reimbursement issues before initiating broader distribution.

Because there is no established coverage, coding or payment for Guardian RT, the firm will work to build reimbursement during the limited launch, McLaughlin said. The cities were chosen in part because they are "good insurance company markets for us."

Medtronic also sought cities with centers that have experience with continued glucose monitoring. The goal is to establish a strong foundation for the product in "centers of excellence" before a broader launch is attempted.

The company does not have a timeline for the more expansive product roll-out but is considering direct-to-consumer advertising.

Medtronic’s Guardian “Real-Time” Glucose Monitor Receives FDA Approval

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