Journal Article

The Accuracy of the FreeStyle Navigator Continuous Glucose Monitoring System in Children With Type 1 Diabetes

Darrell M. Wilson, Mariya J. Dontchev, Larry A. Fox, Roy W. Beck, Peter Chase, Katrina J. Ruedy, Craig Kollman, the DirecNet Study Group, Eva Tsalikian, Stuart A. Weinzimer, William V. Tamborlane

2007

Overview

The Accuracy of the FreeStyle Navigator Continuous Glucose Monitoring System in Children With Type 1 Diabetes Darrell M. Wilson , MD , Roy W. Beck , MD, PHD , William V. Tamborlane , MD , Mariya J. Dontchev , MPH , Craig Kollman , PHD , Peter Chase , MD , Larry A. Fox , MD , Katrina J. Ruedy , MSPH , Eva Tsalikian , MD , Stuart A. Weinzimer , MD and the DirecNet Study Group From the DirecNet Coordinating Center, Jaeb Center for Health Research, Tampa, Florida Address correspondence and reprint requests to Darrell M. Wilson, MD, DirecNet Coordinating Center, Jaeb Center for Health Research, 15310 Amberly Dr., Suite 350, Tampa, FL 33647. E-mail: direcnet{at}jaeb.org Abstract OBJECTIVE —To evaluate the accuracy and precision of the FreeStyle Navigator continuous glucose monitoring system in children with type 1 diabetes. RESEARCH DESIGN AND METHODS —In 30 children with type 1 diabetes (mean age 11.2 ± 4.1 years), the Navigator glucose values were compared with reference serum glucose values of blood samples obtained in an inpatient clinical research center and measured in a central laboratory using a hexokinase enzymatic method and in an outpatient setting with a FreeStyle meter. Median absolute difference (AD) and median relative absolute difference (RAD) were computed for sensor-reference and sensor-sensor pairs. RESULTS —The median AD and RAD were 17 mg/dl and 12%, respectively, for 1,811 inpatient sensor-reference pairs and 20 mg/dl and 14%, respectively, for 8,639 outpatient pairs. The median RAD between two simultaneous Navigator measurements ( n = 1,971) was 13%. Ninety-one percent of sensors in the inpatient setting and 81% of sensors in the outpatient setting had a median RAD ≤20%. CONCLUSIONS —The Navigator’s accuracy does not yet approach the accuracy of current-generation home glucose meters, but it is sufficient to believe that the device has the potential to be an important adjunct to treatment of youth with type 1 diabetes. AD, absolute difference CGMS, continuous glucose monitoring system CRC, clinical research center ISO, International Organisation for Standardization RAD, relative absolute difference Footnotes A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. Accepted September 23, 2006. Received July 5, 2006. DIABETES CARE

• Publisher: American Diabetes Association
• Subject: Accuracy / Adolescent / analysis / Biological and medical sciences / blood / blood glucose / Blood Glucose - analysis / Care and treatment / Child / Child, Preschool / children / Children & youth / Diabetes / Diabetes Mellitus, Type 1 / Diabetes Mellitus, Type 1 - blood / Diabetes. Impaired glucose tolerance / Diagnosis / Endocrine pancreas. Apud cells (diseases) / Endocrinopathies / Etiopathogenesis. Screening. Investigations. Target tissue resistance / Exercise Test / Female / Glucose / Glucose monitors / hexokinase / Humans / Hyperglycemia / Inpatients / insulin-dependent diabetes mellitus / Male / Medical sciences / monitoring / Monitoring systems / Monitoring, Ambulatory / Monitoring, Ambulatory - standards / Mortality / Outpatients / Reading / Reproducibility of Results / Research centers / Risk factors / Sensitivity and Specificity / Statistical methods / Type 1 diabetes / youth