Evaluation of a Continuous Glucose Monitoring System for Home-Use Conditions

Objective: To evaluate the safety and effectiveness of the FreeStyle Navigator Continuous Glucose Monitoring System when used by adult patients with type 1 or 2 diabetes requiring insulin in the home environment. Research design and methods: Multicenter, prospective study enrolling 137 subjects. This was a two-phase study consisting of 20 days of use (“masked period”) without access to continuous glucose readings followed by 21 days of use (‘”unmasked period”) with access to continuous glucose readings and glucose alarms. At the conclusion of the study, all subjects were asked to complete a User’s Questionnaire. Results: A total of 11,487 paired continuous glucose sensor and blood glucose reference results from 961 sensors were evaluated; 77.2 percent were in Clarke error grid zone A and 19.6 percent were in zone B. Only 13.1 percent of the hypoglycemic and 0.5 percent of the hyperglycemic threshold alarms were false alerts. Subjects with type 1 diabetes demonstrated a 55 percent reduction in time spent with significant hypoglycemia (below 55 mg/dL) (P<.0001) from masked to unmasked periods. Their average number of hypoglycemic episodes (below 70 mg/dL) per day fell from 1.1 to 0.8 (P<.0001). Results from patient questionnaires demonstrated high levels of subject satisfaction and the ability to use and understand the system. Conclusions: FreeStyle Navigator Continuous Glucose Monitoring System is safe and effective, and results in a high level of subject satisfaction while used in the home setting. Utilization of continuous glucose monitors with alerts may result in cost offsets by reducing the number and severity of clinically significant events and assisting in the maintenance of optimal glycemic control.