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Practical Aspects of Practical Aspects of Continuous Continuous
Glucose MonitoringGlucose Monitoring20082008
Rosanna Fiallo-Scharer, MDRosanna Fiallo-Scharer, MDLaurel Messer, RN, BSN, CDELaurel Messer, RN, BSN, CDE
Barbara Davis Center for Childhood DiabetesBarbara Davis Center for Childhood Diabetes
Presentation OutlinePresentation Outline
Historical backgroundHistorical background
Accuracy & researchAccuracy & research
Insurance coverage for Insurance coverage for pediatricspediatrics
Barbara Davis Center Barbara Davis Center experienceexperience
Real-Time and retrospective Real-Time and retrospective use of CGM use of CGM
Practical child and family issuesPractical child and family issues
CGMSCGMS®® – FDA- approved in 1999FDA- approved in 1999– Retrospective review of downloaded dataRetrospective review of downloaded data– Principle: Glucose oxidase-coated subcutaneous Principle: Glucose oxidase-coated subcutaneous
sensorsensor
Glucowatch BiographerGlucowatch Biographer– FDA- approved in 2001FDA- approved in 2001– First approved real time device First approved real time device – Principle: reverse iontophoresis through intact skinPrinciple: reverse iontophoresis through intact skin
Real Time Continuous Glucose Real Time Continuous Glucose MonitoringMonitoring
Freestyle Navigator
Dexcom STS
Paradigm Real Time System
Inpatient Accuracy StudyInpatient Accuracy Study
Principal Aim:Principal Aim:
To assess the accuracy of the To assess the accuracy of the Medtronic MiniMed CGMS and the Medtronic MiniMed CGMS and the GlucoWatch Biographer II vs. gold GlucoWatch Biographer II vs. gold standard plasma glucose standard plasma glucose measurements in children with T1DMmeasurements in children with T1DM
Subject DemographicsSubject Demographics
• 91 Children and 91 Children and AdolescentsAdolescents
• 51% Female51% Female• 43% Pumpers43% Pumpers• Mean HbA1c = 7.8Mean HbA1c = 7.8%%
Ages of Subjects
3 to < 7
7 to < 12
12 to < 18
Daily Glucose VariationsDaily Glucose Variations
40
60
80
100
120
140
160
180
200
220
240
260
280
300
320
340
360
380
400
2:00 PM 3:00 PM 4:00 PM 5:00 PM 6:00 PM 7:00 PM 8:00 PM 9:00 PM 10:00PM
11:00 PM 12:00AM
1:00 AM 2:00 AM 3:00 AM 4:00 AM 5:00 AM 6:00 AM 7:00 AM 8:00 AM 9:00 AM 10:00AM
11:00AM
12:00PM
1:00 PM 2:00 PM
gluc
ose
(mg/
dl)
Procedure•Regular meals and insulin doses•GS glucose q30-60 min
ResultsResultsnn r Mean RAD Median RAD Within r Mean RAD Median RAD Within
ISOISO
GWB GWB 3,6723,672 0.860.86 22% 22% 16%16% 80%80%
CGMS CGMS (original) (original) 5,6585,658 0.770.77 26% 26% 19%19% 53%53%
CGMS CGMS (Modified) (Modified) 1,120 1,120 0.90 0.90 16% 16% 11%11% 72% 72%
UltraUltra 2,0682,068 0.970.97 6% 6% 9%9% 94%94%
ISO Criteria: If reference glucose ≤ 75 mg/dL, sensor glucose within ± 15 mg/dL; if reference glucose > 75 mg/dL, sensor glucose within ± 20%.
Diabetes Technology &Therapeutics Vol 5 (5), 2003
Factors Factors NOTNOT Impacting Accuracy Impacting Accuracy For Either the GW or CGMSFor Either the GW or CGMS
Age of the SubjectAge of the Subject
BMI (body mass index)BMI (body mass index)
Sensor age (CGMS)Sensor age (CGMS)
Location of GWB placementLocation of GWB placement– Upper vs lower armUpper vs lower arm– Inner vs outer armInner vs outer arm
0%
5%
10%
15%
20%
25%
30%
35%
40%
0 50 100 150 200 250 300 350 400
Reference Glucose (mg/dL)
Median RAD
GWB
Original CGMS
Modified CGMS
Sensor Accuracy by Glucose LevelSensor Accuracy by Glucose Level
CGMS Sensitivity and False Alarm CGMS Sensitivity and False Alarm rate for detection of hypoglycemiarate for detection of hypoglycemia
Alarm Setting Alarm Setting SensitivitySensitivity False Alarm RateFalse Alarm Rate
(mg/dl)(mg/dl)
6060 49%49% 58%58%
8080 84%84% 64%64%
100 100 100%100% 75%75%
120 120 100%100% 84%84%
Down alertDown alert
Only 24% and 8% of truly hypoglycemic Only 24% and 8% of truly hypoglycemic incidents were detected by the simple incidents were detected by the simple alarm during the hypoglycemia test and alarm during the hypoglycemia test and overnight, respectively overnight, respectively
Combining the simple alarm with the down Combining the simple alarm with the down alert improves those sensitivity rates to alert improves those sensitivity rates to 88% and 77%, respectively 88% and 77%, respectively
Diabetes Technol Ther. 2004 Oct; 6(5): 559-66
Accuracy of the Freestyle Navigator Accuracy of the Freestyle Navigator and Guardian RTand Guardian RT
Diabetes Care. 2007 Jan; 30 (1):59-64
ResultsResultsnn Median RAD Median RAD Within ISO Within ISO
Guardian RTGuardian RT 1,4341,434 14% 14% 64% 64%
Navigator Navigator 1,8111,811 12% 12% 74%74%
UltraUltra 2,068 2,068 9% 9% 94%94%
ISO Criteria: If reference glucose ≤ 75 mg/dL, sensor glucose within ± 15 mg/dL;
if reference glucose > 75 mg/dL, sensor glucose within ± 20%.
These devices have sufficient accuracy to These devices have sufficient accuracy to allow tracking of glucose valuesallow tracking of glucose values
However, neither device is as accurate as However, neither device is as accurate as meters presently available on the marketmeters presently available on the market
Particularly useful for detecting post-Particularly useful for detecting post-prandial glycemic excursions and prandial glycemic excursions and overnight glucose trendsovernight glucose trends
ConclusionsConclusions
GWB2 Randomized Controlled GWB2 Randomized Controlled TrialTrial
Diabetes Care. 2005 May; 28(5):1101-6
Ultra Daily UseUltra Daily Use
First Month:First Month: 5.1 5.1 ± 1.6 in Usual ± 1.6 in Usual Care group, 5.6Care group, 5.6 ± 1.7 in GWB group± 1.7 in GWB group
Third Month:Third Month: 5.1 ± 1.8 in Usual Care 5.1 ± 1.8 in Usual Care group, 5.3 ± 1.6 in GWB groupgroup, 5.3 ± 1.6 in GWB group
Sixth Month:Sixth Month: 4.8 ± 1.7 in Usual Care 4.8 ± 1.7 in Usual Care group, 5.1 ± 1.7 in GWB groupgroup, 5.1 ± 1.7 in GWB group
GW2B useGW2B use
First Month:First Month: 2.1 2.1 ± 0.8 uses per week ± 0.8 uses per week (64% = at least 2 sensors/ week)(64% = at least 2 sensors/ week)Third Month:Third Month: 1.6 ± 0.7 uses per week (7 of the 99 subjects discontinued 1.6 ± 0.7 uses per week (7 of the 99 subjects discontinued GW2B use)GW2B use)
Sixth Month:Sixth Month: 1.5 ± 0.6 uses per week (26 of the 98 subjects discontinued 1.5 ± 0.6 uses per week (26 of the 98 subjects discontinued GW2B use)GW2B use)Questionnaire regarding non-use of the GW2B (55 subjects)Questionnaire regarding non-use of the GW2B (55 subjects)
76% = “skin irritation”76% = “skin irritation”56% = “skips too frequently”56% = “skips too frequently”47% = “alarms too frequently”47% = “alarms too frequently”33% = “readings not accurate”33% = “readings not accurate”31% = “too busy to use it”31% = “too busy to use it”22% = “forget to use it”22% = “forget to use it”
18% = “did not help with diabetes18% = “did not help with diabetes management” management”
Lesson learned:Lesson learned:
For CGM to help with diabetes For CGM to help with diabetes management, patients must use management, patients must use them!them!
Freestyle Navigator Pilot trialFreestyle Navigator Pilot trial
Journal Pediatr. 2007 Oct; 151 (4): 388-93
SummarySummary
57 pediatric subjects enrolled57 pediatric subjects enrolled– 30 Pumpers30 Pumpers– 27 MDI27 MDI
A1c data collected at 13 weeksA1c data collected at 13 weeks
Voluntary sensor use offered after 13 weeksVoluntary sensor use offered after 13 weeks
73% of pump users continued to use sensor at 73% of pump users continued to use sensor at 12 months and 78% of MDI users continued at 12 months and 78% of MDI users continued at 10 months (median hrs/wk 98 and 85 10 months (median hrs/wk 98 and 85 respectively)respectively)
A Randomized Clinical Trial to A Randomized Clinical Trial to Assess the Efficacy of Real-Assess the Efficacy of Real-Time Continuous Glucose Time Continuous Glucose
Monitoring in the Management Monitoring in the Management of Type 1 Diabetesof Type 1 Diabetes
funded by a grant from funded by a grant from the Juvenile Diabetes Research the Juvenile Diabetes Research
FoundationFoundation
Clinical Trial DesignClinical Trial Design
450 subjects age >=8 years• 330 with A1c >7.0% and 120 with HbA1c <7.0%• 1/3 in each age group: 8-<15, 15-<25, >25• 50% pump users, 50% MDI
Randomization to RT-CGM or Usual Care• Navigator, DexCom, Paradigm/Guardian REAL-Time
Primary outcome at 6 months
Months 7-12: both groups use RT-CGM
Outcomes: HbA1c, hypoglycemia, quality of life
Cost-effectiveness ancillary study
Current statusCurrent statusJDRF RCTJDRF RCT
6 month data collection already completed6 month data collection already completed
12 month data collection still in progress.12 month data collection still in progress.
Insurance coverage for Insurance coverage for pediatricspediatrics
Currently only one device approved for Currently only one device approved for pediatric usepediatric use
Real time technology not universally Real time technology not universally coveredcovered
Some success with approval on case by Some success with approval on case by case basiscase basis
Usually approved on appeals processUsually approved on appeals process
Presentation OutlinePresentation Outline
RT- CGM systems for pediatricsRT- CGM systems for pediatrics
Accuracy & researchAccuracy & research
Insurance coverage for pediatricsInsurance coverage for pediatrics
Barbara Davis Center experienceBarbara Davis Center experience
Real-Time and retrospective use Real-Time and retrospective use of CGMof CGM
Practical child and family issuesPractical child and family issues
Barbara Davis CenterBarbara Davis Centerexperience with CGMexperience with CGM
Currently: 100+ pediatric pts on CGMCurrently: 100+ pediatric pts on CGM
5 years old through adulthood5 years old through adulthood
Commercially: Paradigm REAL-Time, Dexcom Commercially: Paradigm REAL-Time, Dexcom SEVENSEVEN
Research: NavigatorResearch: Navigator
Varied experiences with devicesVaried experiences with devices
Using a sensor on daily basisUsing a sensor on daily basis
Insert sensor (every 3-7 days)Insert sensor (every 3-7 days)Warm up period with no glucose readingsWarm up period with no glucose readingsEntering fingerstick BG for calibrationsEntering fingerstick BG for calibrationsDevice starts reading REAL-TIME Device starts reading REAL-TIME informationinformationOccasional downloading Occasional downloading of device for of device for RETROSPECTIVE RETROSPECTIVE informationinformation
Real Time CGM UseReal Time CGM Use
SENSOR glucose levels SENSOR glucose levels Different from BG levels due to lag timeDifferent from BG levels due to lag time
Updates every 1-5 minutesUpdates every 1-5 minutes
ArrowsArrows
AlarmsAlarms
Trend informationTrend information
Real Time CGM UseReal Time CGM Use
EDUCATION POINT:EDUCATION POINT:– Must always do a BG for insulin, Must always do a BG for insulin,
treatment and management decisionstreatment and management decisions
WHY?
• No device currently FDA approved for replacement therapy
• Sensor may not be reading accurately
Retrospective dataRetrospective dataDownloaded at home or in clinicDownloaded at home or in clinic
(anyone have experience with this?)(anyone have experience with this?)
Retrospective dataRetrospective dataEDUCATION POINTSEDUCATION POINTS
Must know the WHY before knowing WHAT Must know the WHY before knowing WHAT to change!to change!
Make dosing changes if BG/SG is out of Make dosing changes if BG/SG is out of range range 2 out of 3 days2 out of 3 days
Important to look at trendsImportant to look at trendsLook at most recent weekLook at most recent week
Questions before changing: missed bolus? Questions before changing: missed bolus? menses? Illness? Bad pump set? Mistake in dose? menses? Illness? Bad pump set? Mistake in dose? Sports?Sports?
Retrospective dataRetrospective data
Trend graphTrend graph
(sensor daily overlay, modal day)(sensor daily overlay, modal day)
Pediatric issuesPediatric issues
ExpectationsExpectations
Sensor stickingSensor sticking
SportsSports
AlarmsAlarms
CalibrationsCalibrations
Family dynamicsFamily dynamics
Pediatric issuesPediatric issues
ExpectationsExpectations
ExpectationsExpectationsNo fingerstick BGsNo fingerstick BGsWill read from the moment you put onWill read from the moment you put onAlarms will prevent all highs and lowsAlarms will prevent all highs and lows
Reality:Reality:4-8 BGs per day4-8 BGs per dayPeriods where not calibrated, not readingPeriods where not calibrated, not readingSensor errors for no reasonSensor errors for no reasonAlarms annoyingAlarms annoying
Pediatric issuesPediatric issues
Sensor stickingSensor stickingThree main problems:Three main problems:
1) Sensor does not stick1) Sensor does not stickTry different types of preps (IV prep, skin prep, Skin Try different types of preps (IV prep, skin prep, Skin Tac, Mastisol, tincture of benzoine Tac, Mastisol, tincture of benzoine
2) Tape or preps causes skin reactions2) Tape or preps causes skin reactionsTry different preps or tapesTry different preps or tapesUse IV3000/Tegaderm FIRST, and cut hole for Use IV3000/Tegaderm FIRST, and cut hole for sensor to insert throughsensor to insert through
3) Not enough skin “real estate” 3) Not enough skin “real estate” Try different sensorsTry different sensorsPinch up even if not indicated Pinch up even if not indicated
Chart on handoutChart on handout
PlacementPlacementConsider where least impact and movementConsider where least impact and movement
Arm– can cover with ace bandage for extra Arm– can cover with ace bandage for extra support (take off at night)support (take off at night)
SweatingSweatingUse antiperspirant under tapeUse antiperspirant under tape
BreakingBreakingNever take CGM receiver out into gameNever take CGM receiver out into game
Pediatric issuesPediatric issues
SportsSportsPROBLEM: CGM sensors fall off, sweat off, get broken
Calibration reminder * Calibration Calibration reminder * Calibration error * Replace sensor * High error * Replace sensor * High Glucose * Low Glucose * Projected Glucose * Low Glucose * Projected Low Glucose * Projected High Low Glucose * Projected High Glucose * Meter BG Now * Sensor Glucose * Meter BG Now * Sensor end * Wend * Weak signal * Disconnected * Low transmitter * Bad transmitter * Sensor error * Bad sensor
Pediatric issuesPediatric issues
AlarmsAlarmsPROBLEM: Alarms can become Alarms can become overwhelming/ annoying Why?.... overwhelming/ annoying Why?....
HIGH ALARM: 250-300 mg/dl*HIGH ALARM: 250-300 mg/dl*
LOW ALARM: 70-80 mg/dlLOW ALARM: 70-80 mg/dlConsider higher with hypoglycemia unawarenessConsider higher with hypoglycemia unawareness
Can gradually “tighten” alarms as glucose levels get Can gradually “tighten” alarms as glucose levels get tightertighter
**My opinion only!My opinion only!
Pediatric issuesPediatric issues
AlarmsAlarms
GOAL: Set alarms that are GOAL: Set alarms that are MEANINGFUL and will NOT drive the MEANINGFUL and will NOT drive the
child crazy!child crazy!
Can I change the type of alarm notice?”Navigator:
YES: vibrate or sound at three different volumes
Medtronic: YES: vibrate or sound at different volumes
Dexcom: NO: Will first vibrate then sound at increasing volumes
Pediatric issuesPediatric issues
AlarmsAlarms
Solution: Improvise!Solution: Improvise!On bedside table (in a glass) or under pillow on On bedside table (in a glass) or under pillow on vibratevibrate
In hallway outside of roomIn hallway outside of room
Baby monitor Baby monitor
Sibling in the room!Sibling in the room!
Spy equipmentSpy equipment
Paradigm Real-Time: More difficult because Paradigm Real-Time: More difficult because usually under blankets– new tech coming soon!usually under blankets– new tech coming soon!
Pediatric issuesPediatric issues
Overnight alarmsOvernight alarms
PROBLEM: Parent/child has difficulty hearing Parent/child has difficulty hearing alarms at nightalarms at night
Pediatric issuesPediatric issues
CalibrationsCalibrations
GOAL: Be the BOSS of the Calibration: Only GOAL: Be the BOSS of the Calibration: Only enter a calibration if BGs are STABLEenter a calibration if BGs are STABLE
SOLUTION: Calibrate before meals or 2 hours SOLUTION: Calibrate before meals or 2 hours after food or insulin shotafter food or insulin shot– Less likely to get a failed calibration alarmLess likely to get a failed calibration alarm– More likely to get accurate sensor readingsMore likely to get accurate sensor readings
PROBLEM: Calibration alarms annoying, Calibration alarms annoying, inconvenient, and when fail, are frequentinconvenient, and when fail, are frequent
Family issues and dynamicsFamily issues and dynamics
Adaptation: “It is just part of our life now. I wear it all the Adaptation: “It is just part of our life now. I wear it all the time and don’t think much about it anymore.” 12 y.o. time and don’t think much about it anymore.” 12 y.o. femalefemale
Anxiety: “ I was worried that my mom was mad at my blood Anxiety: “ I was worried that my mom was mad at my blood sugars all the time so I didn’t want to show her” 11 y.o. sugars all the time so I didn’t want to show her” 11 y.o. malemale
Ambivalence: “I like it when it works but I worry it is going to Ambivalence: “I like it when it works but I worry it is going to fall out and I will have to put a new sensor in again”fall out and I will have to put a new sensor in again”
14 y.o. male14 y.o. male
Family issues and dynamicsFamily issues and dynamics
THE BOTTOM LINE: THE BOTTOM LINE: They have to live They have to live with diabetes, not with CGMwith diabetes, not with CGM
Interval wear (example: 1 Interval wear (example: 1 sensor/week)sensor/week)
Occasional wear (example: during Occasional wear (example: during finals)finals)
Try again laterTry again later
The future of CGMThe future of CGM
SmallerSmaller
Longer sensor wearsLonger sensor wears
Less calibrationsLess calibrations
More insurance coverageMore insurance coverage
Closed loop system (insulin pump Closed loop system (insulin pump responds to sensor glucose levels)responds to sensor glucose levels)
Implantable sensorsImplantable sensors