title: Hypoglycemic Accuracy and Improved Low Glucose Alerts of the Latest Dexcom G4 Platinum Continuous Glucose Monitoring System.
abstract: OBJECTIVE
  Accuracy of continuous glucose monitoring (CGM) devices in hypoglycemia has been a widely reported shortcoming of this technology. We report the accuracy in hypoglycemia of a new version of the Dexcom (San Diego, CA) G4 Platinum CGM system (software 505) and present results regarding the optimum setting of CGM hypoglycemic alerts.
  
  
  METHODS
  CGM values were compared with YSI analyzer (YSI Life Sciences, Yellow Springs, OH) measurements every 15 min. We reviewed the accuracy of the CGM system in the hypoglycemic range using standard metrics. We analyzed the time required for the CGM system to detect biochemical hypoglycemia (70 mg/dL) compared with the YSI with alert settings at 70 mg/dL and 80 mg/dL. We also analyzed the time between the YSI value crossing 55 mg/dL, defined as the threshold for cognitive impairment due to hypoglycemia, and when the CGM system alerted for hypoglycemia.
  
  
  RESULTS
  The mean absolute difference for a glucose level of less than 70 mg/dL was 6 mg/dL. Ninety-six percent of CGM values were within 20 mg/dL of the YSI values between 40 and 80 mg/dL. When the CGM hypoglycemic alert was set at 80 mg/dL, the device provided an alert for biochemical hypoglycemia within 10 min in 95% of instances and at least a 10-min advance warning before the cognitive impairment threshold in 91% of instances in the study.
  
  
  CONCLUSIONS
  Use of an 80 mg/dL threshold setting for hypoglycemic alerts on the G4 Platinum (software 505) may provide patients with timely warning of hypoglycemia before the onset of cognitive impairment, enabling them to treat themselves for hypoglycemia with fast-acting carbohydrates and prevent neuroglycopenia associated with very low glucose levels.
authors.affiliation: 1 Menlo Park , California.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Peyser
authors.affiliation: 2 Dexcom, Inc. , San Diego, California.
authors.forename: Katherine
authors.initials: K
authors.lastname: Nakamura
authors.affiliation: 2 Dexcom, Inc. , San Diego, California.
authors.forename: David
authors.initials: D
authors.lastname: Price
authors.affiliation: 2 Dexcom, Inc. , San Diego, California.
authors.forename: Lucas C
authors.initials: LC
authors.lastname: Bohnett
authors.affiliation: 3 University of Washington , Seattle, Washington.
authors.forename: Irl B
authors.initials: IB
authors.lastname: Hirsch
authors.affiliation: 2 Dexcom, Inc. , San Diego, California.
authors.forename: Andrew
authors.initials: A
authors.lastname: Balo
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D001786:Blood Glucose / Q000032:analysis*; D015190:Blood Glucose Self-Monitoring / Q000295:instrumentation* / Q000379:methods; D003072:Cognition Disorders / Q000139:chemically induced / Q000517:prevention & control; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000188:drug therapy*; D005260:Female; D006801:Humans; D007003:Hypoglycemia / Q000139:chemically induced / Q000517:prevention & control*; D007004:Hypoglycemic Agents / Q000008:administration & dosage; D007328:Insulin / Q000008:administration & dosage; D007332:Insulin Infusion Systems / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012016:Reference Values; D015203:Reproducibility of Results; D012984:Software; D013997:Time Factors; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin