Juvenile Diabetes Research Foundation (JDRF), NIH, Diabetes UK.

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 Ϯ 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 ϭ 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 Յ20%.CONCLUSIONS -The Navigator's accuracy does not yet approach the accuracy of currentgeneration 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. Diabetes Care 30:59 -64, 2007D irect reading, near-continuous, minimally invasive glucose sensors hold great promise for improving the care of patients with diabetes and other abnormalities of glucose metabolism. These sensors can provide both a measure of the current glucose concentration as well as glucose trends, with alarms for high and low thresholds and predicted hypo-and hyperglycemia. With the recent demonstration that good glycemic control reduces mortality and morbidity in acutely ill nondiabetic patients (1,2), glucose sensors could have an even more expanded role outside the realm of diabetes.A major issue in evaluating the utility of a real-time continuous glucose monitor is its accuracy across a wide range of glucose levels. Previously, we reported on the accuracy of the GlucoWatch G2 Biographer (Cygnus, Redwood City, CA) (3) and the continuous glucose monitoring system (CGMS; Medtronic Minimed, Northridge, CA) (4) in children with type 1 diabetes. The purpose of this article is to report on the accuracy of the FreeStyle Navigator CGMS in children.RESEARCH DESIGN AND METHODS -The study was conducted by the Diabetes Research in Children Network (DirecNet) at five clinical centers. A data and safety monitoring board and the institutional review boards at each center approved the study protocol, consent form, and assent form. A parent or guardian and each subject aged Ն7 years gave written consent and assent, respectively.Eligible subjects were between 3 and 18 years old with a clinical diagnosis of type 1 diabetes of Ն1-year duration. Subjects initially used a Navigator that was blinded so that glucose values could not be seen for approximately 1 week at home. During this time, glucose levels were checked with the built-in FreeStyle blood glu...

Subjects awoke to 29% of individual alarms and to 66% of alarm events. Subjects awoke during all alarm events when hypoglycemia was confirmed, but there was a high incidence of false alarms.

The goal of this study was to address whether antiislet autoantibodies appear sequentially or simultaneously before the onset of type I diabetes. We analyzed sequential serum samples from 155 siblings and offspring (aged < 7 yr) of patients with type I diabetes from the Denver Diabetes Autoimmunity Study in the Young study and from a separate group of first degree relatives (aged 2-40 yr) for autoantibodies reacting with three defined autoantigens: glutamic acid decarboxylase (GAD65), insulin, and ICA512/IA-2. The youngest age at which 1 of the 3 autoantibodies appeared was 1.1 yr, and the oldest was 60.9 yr. Of the total 26 autoantibody conversion events observed, in only 3 instances did more than 1 autoantibody appear simultaneously. Among individuals (n = 12) with sequential conversion to expression of multiple autoantibodies, anti-GAD65 autoantibodies or antiinsulin autoantibodies appeared first (4 expressed antiinsulin autoantibodies first, and 8 anti-GAD65 autoantibodies first). We conclude that antiislet autoantibodies usually appear sequentially and not simultaneously. This corroborates early suggestions that humoral autoimmunity to islets develops chronically in a process usually measured in months to years. As expression of multiple autoantibodies is associated with a high risk of progression to diabetes, and sequential appearance of autoantibodies can occur late in life, long term follow-up is necessary to fully delineate the relationship of diabetes risk to autoantibody expression.