1 / 20

Abstract #156

Accuracy Study of the Medtronic Minimed Continuous Glucose Monitoring System (CGMS) and GlucoWatch ® G2 TM Biographer (GW2B) in Children with Type 1 Diabetes – A GCRC-based study. Abstract #156. Background: DirecNet. Di abetes Re search in C hildren Net work

gail
Download Presentation

Abstract #156

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Accuracy Study of the Medtronic Minimed Continuous Glucose Monitoring System (CGMS) and GlucoWatch® G2TM Biographer (GW2B) in Children with Type 1 Diabetes – A GCRC-based study Abstract #156

  2. Background: DirecNet • Diabetes Research in Children Network • NIH funded collaborative study group • 5 clinical centers, central laboratory, coordinating center, and representatives from NICHD and NIDDK • Objective: to critically evaluate the clinical usefulness of current and future glucose sensors in children and adolescents

  3. Goals of Present Study To determine the accuracy of the CGMS and G2B • During hypoglycemia and hyperglycemia • Over a broad age range in pediatrics • Comparing nighttime to daytime readings • Determine if accuracy changes as sensors age

  4. Devices used – GW2B • GlucoWatch 2 - Cygnus • Two hour calibration • Provides a glucose reading every 10 minutes • Data can be generated for up to 13 hours • GlucoWatch glucose lags serum glucose by 17.5 minutes and this lag was adjusted for in assessing accuracy • For details of study see Poster #432

  5. Devices used - CGMS • Medtronic Minimed • Functions up to 72 hours • Data from subcutaneous glucose is stored and retrospectively reviewed • In 11/02 the sensor manufacturing process was modified • We studied 115 “original” and 25 “modified” sensors • For details of study see Poster #387

  6. Methods • All subjects admitted to a GCRC for ≈ 24 hours • Sensors calibrated to a home glucose meter • Serum glucose levels sent to a central lab • Samples every hour during the day, and every ½ hour from 9 PM to 7 AM • Samples every 5 minutes for up to 90 minutes following insulin induced hypoglycemia • Samples every 5 minutes for 1 hr following meal induced hyperglycemia

  7. Subject Demographics • 91 Children and Adolescents • 51% Female • 43% Pumpers • Mean HbA1c = 7.8%

  8. Young Subject Wearing Devices

  9. Example of data generated from CGMS use

  10. Graphic example of data generated from GlucoWatch 2

  11. Measures of Accuracy • Pearson’s correlation • Relative absolute difference (RAD) % • |(sensor – reference)/reference| x 100% • ISO criteria (proposed) • Reference glucose ≤75 mg/dL • Sensor value within ±15 mg/dL • Reference glucose value >75 mg/dL • Sensor value within ±20%

  12. Overall Accuracy Results ISO Criteria: If reference glucose ≤ 75 mg/dL, sensor glucose within ± 15 mg/dL; if reference glucose > 75 mg/dL, sensor glucose within ± 20%.

  13. Factors NOT Impacting Accuracy For Either the GW2B or CGMS • Age of the Subject • Time of Day (Nighttime vs. Daytime) • BMI (body mass index) • Location of GW2B placement • Upper vs lower arm • Inner vs outer arm

  14. Effect of Glucose Concentration on Accuracy Assessed by Median RAD%

  15. GW2B Function By Hours Of Use Sensor age had no effect on CGMS function

  16. Sensitivity and False Positive rate for detection of hypoglycemia (<60 mg/dl)

  17. Adverse Events • GlucoWatch • Minor skin irritation in 29% of GW2B uses • No severe or persistent skin reactions • CGMS • No significant skin irritation or site infections

  18. Summary • GW2B accuracy was unaffected by site of wear • The GW2B was less accurate in the last 4-5 hours of use, whereas CGMS accuracy was unaffected by sensor age • When compared to the original CGMS, the modified CGMS was more accurate in all measures

  19. Summary • For both the GW2B and the CGMS: • Subject age had no effect on accuracy • Time of the day had no effect on accuracy • Accuracy was greater for hyperglycemia than for hypoglycemia • Neither device is as accurate as currently available meters

  20. Yale University • William Tamborlane • Stuart Weinzimer • Elizabeth Boland • University of Minnesota Central Laboratory: • Michael Steffes • Jean Bucksa • Maren  Nowicki • Jaeb Center for Health Research • Roy Beck • Katrina Ruedy • Craig Kollman • Andrea Booth • Gladys Bernett • Barbara Davis Center • H. Peter Chase • Rosanna Fiallo-Scharer • Jennifer Fisher • University of Iowa • Eva Tsalikian • Michael Tansey • Linda Larson • Nemours Children’s Clinic • Tim Wysocki • Nelly Mauras • Kristen Gagnon • Stanford University • Bruce Buckingham • Darrell Wilson • Jennifer Block

More Related