GLUCOWATCH G2 BIOGRAPHER H. PETER CHASE, MD

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GLUCOWATCH G2 BIOGRAPHERH. PETER CHASE, MD

• INTRODUCTION
• ACCURACY DATA
• HOME PILOT TRIAL
• DIRECNET STUDY GROUP
• SUMMARY

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GlucoWatch G2 Biographer
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GlucoWatch G2 Biographer (GW2B)

• Measures interstitial glucose extracted by
  reverse iontophoresis
• Requires a single calibration value following the
  2-hour warm-up period
• Glucose readings every 10 minutes for 13 hours
• Values range from 40 to 400 mg/dL

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GlucoWatch G2 Biographer
INTRODUCTION i) Second generation model
(G2B) ii) Warm-up 2 hours ? enter BG value iii)
Reverse iontophoresis AAA battery iv) Pulls
interstitial fluid (including glucose) into
gel discs in Auto Sensor v) Readings as often
as every 10 min for up to 13 hrs (max 76
readings Ave 55)
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INTRO G2B
vi) Numerous data integrity checks are performed
that monitor environmental factors (temperature,
sweating), sensor function, and performance. If
the reading fails the data integrity checks, it
is skipped because the value may be
incorrect. vii) The G2 Biographer averages the
reading obtained in the most recent cycle with
the reading obtained in the previous 10 minute
cycle.
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INTRO G2B
vii) Alarms for Hypo/hyper-glycemia
(level set by user) Pending low in next 10-20
minutes Low or drop 30 minutes prior to
detection of sweat viii) Up or down arrows with
change of 9mg/dl
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INTRO G2B Major uses
i) Nocturnal hypoglycemia ii) Postprandial
hyperglycemia iii) Hypoglycemic unawareness iv)
Gestational diabetes v) Type 2 diabetes vi)
Other (e.g. Glycogen Storage Dis.)
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G2B Positives

• Detection of lows particularly during the night
• Making aware of post-prandial highs
• Watchdog effect
• Detecting patterns
• e-mailing data to MD or RN

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INTRO G2BNegatives

• Skipped readings with sweating
• Not always awakening for alarm
• Not waterproof
• Skin itching, blisters, (remove sensor with
  Unisolve) (adults gt youth)
• Wont take first calibration (6) due to sweat,
  rapid BG change, weak signal
• Other skipped readings

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Side Effects

• No serious skin reactions
• No other problems

Mild Irritation example
Moderate Irritation example
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GlucoWatch Function

• Sensor calibration
• 1st attempt 94
• 2nd attempt 2
• Failed 4
• Sensor lifespan
• 14.5 hours (Full) 81
• 10.0 to 14.5 hours 3
• 6.0 to 10.0 hours 6
• lt6.0 hours 10
• Of 14,232 possible GW2B measurements
• 17 were skipped
• Excludes sensors stopped early for logistical
  reasons.
• DirecNet Data

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Analyzer Features
Analyzer alert settings may differ from
Biographer settings
Biographer DOWN alerts
220 mg/dL
160 mg/dL
Trend arrows not shown on Analyzer screen
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Part II ACCURACY STUDIES IN CHILDREN

• Eastman RC, Chase HP, Buckingham B, et al.
  Pediatric Diabetes 3127, 2002
• Clinic setting
• 3 First GW Biographers/subject
• Multiple wear sites
• Compared to HemoCue meter

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ACCURACY STUDIES IN CHILDREN

• DirecNet Study Group
• i) Inpatient
• ii) 2 4 G2Bs/subject
• iii) Upper and lower arm sites
• iv) Compared to hospital lab BG

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ACCURACY STUDIES IN CHILDREN
GWB G2B (Pediatric
Diabetes) (DirecNet) Settings Clinic (14
Hr) Inpatient (26 Hr) No. Youth 66
(11.9 yrs) 89 (9.9 yrs) Sensors
198 285 Comparisons 1313
3,659 Skipped Readings 14 17
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ACCURACY STUDIES IN CHILDREN

• GWB G2B
• (Pediatric Diabetes) (DirecNet)
• Mean Difference -17 mg/dl 2.1 mg/dl
• Absolute Difference 34 mg/dl 30.8 mg/dl
• iii) MARD 21 22
• Mean Difference Sensor value Lab value
• Absolute Difference Absolute value of
  difference
• MARD Mean Absolute Relative Difference
• Sensor value lab value x 100
• lab value

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ACCURACY STUDIES IN CHILDREN
GWB G2B (Pediatric
Diabetes) (DirecNet) iv) Correlation Coef.
0.82 0.86 v) Consensus Error 97
97 Grid (A B) vi) Paired Values
76 74 within 20
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ACCURACY STUDIES IN CHILDRENHYPOGLYCEMIA
Overnight Hypoglycemia (lt70mg/dl)

• 18 episodes by G2B (DirecNet)
• 2) 10 episodes Lab glucose matched
• 8 episodes not confirmed

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4/7
4/8
4/9
4/10
0534 BG-54
0405 BG-44
True lows detected by alarm
13 yo on CSII Basal rates had been erased
Accidentally put in rates 12 hours off
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4/13
4/12
BG 177
13 yo on CSII with correct/new basal rates in
place HbA1c 7.4
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Part III HOME PILOT STUDY
Use of the GlucoWatch Biographer (GWB) in
Children with Type 1 Diabetes (T1DM) Chase HP,
Roberts MD, Wightman C, Klingensmith G, Garg SK,
et al. Pediatrics 111790-794,2003. Objective
To determine the usefulness of the GWB for
1) detection of hypoglycemia 2)
improving glucose control in children and
adolescents with T1DM in a home environment

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40 Randomized Study Subjects

• Age 7-17 years mean 12.4 yrs
• Type 1 diabetes 1 yr (mean 6.3 yrs)
• HbA1c gt8 on 2 occasions during prior 6 months
• Absence of clinically significant disease or
  condition that would interfere with participation
  in the trial
• No history of severe hypoglycemia for 6 months
  preceding entry into the trial (many had prior
  history of severe hypoglycemia gt6 months before
  study)
• Willingness to be randomly assigned to standard
  care or standard care with Biographer monitoring
  4 times/week

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Study Plan

• Randomization to two treatment groups
• standard care in the home environment
• standard care in the home environment with
  GlucoWatch Biographer monitoring
• Biographer alerts set to 70 and 300 mg/dL
• Confirmation of alerts by conventional blood
  glucose monitoring
• Both groups weekly review of SMBG data (GWB
  data) and a phone call from HPC

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Outcome Measures

• HbA1c measured at baseline, and at 1 and 3 months
  (DCA-2000)
• Hypoglycemia events determined
• - Biographer alert 70 mg/dl
• - Hypoglycemic event SMBG lt70 mg/dl
• Surveys
• Fear of Hypoglycemia
• Quality of Life (DCCT)

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GWB HOME USE
Week 1-4 5-8 9-13 Uses/wk 4.1
3.7 3.0 Hi BG 4.7 2.5 3.1 Lo BG
14.2 16.6 16.5 GWB readings
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Frequency of Hypoglycemia Home Meter Blood
Glucose lt 70 mg/dL






plt0.05 versus control
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Median HbA1c by Group vs. Time

plt0.05 versus control group
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Summary and Conclusions

• Biographer use was well tolerated in the home
  environment
• HbA1c was significantly lower (plt0.05) in the
  Biographer treatment group compared to the
  control group after 3 months of treatment
• Biographer users detected significantly more
  hypoglycemia during the day and night than
  non-users
• The Biographer is useful for improving glucose
  control and detecting hypoglycemia in children
  and adolescents with type 1 diabetes

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Reduction in Complications Eastman RC, Chase HP
and Leptien AD Pediatric Diabetes 482-86, 2003

• Using DCCT data, a decline in HbA1c from 9.0 to
  8.4 for 100 subjects for a lifetime would
• Prevent severe eye disease in 20 people
• Prevent blindness in 6 people
• Prevent gross kidney damage in 20 people (8
  needing transplants)
• Prevent 6 cases of neuropathy

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4/19
4/15
0805 BG 305
4/18
1059 BG 259
0733 BG 138
2008 BG 56
Picked up low at calibration
2 GWB tracings Pre-teen girl IDDM x 5yrs Patient
at slumber party
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4/25
5/2
1736 bg350
0908 bg245
1759 bg215
1357 bg175
Went to office No snack given
1009 bg45
1151 bg80
Low alarm at same time as last week (1530) No bg
test
1511 Piano teacher gave candy but did not test
Pre-teen girl IDDM x 5yrs
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Part IV DIRECNET STUDY GROUP
DIabetes REsearch in Children NETwork

• NIH funded collaborative study group (NICHD and
  NIDDK)
• 5 Centers Denver, Iowa, Nemours (FL), Stanford
  and Yale.
• Coordinating Center Jaeb Center for Health
  Research, Tampa, FL

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DIRECNET STUDY GROUP

• Objective to critically evaluate the clinical
  usefulness of current and future glucose sensors
  in youth with T1DM.
• Initial inpatient study accuracy of G2B and of
  CGMS. Abstracts 156 OR,
• 432-P and 387-P .
• v) Next study Similar to the GWB Pilot Trial
  done in Denver, but with 200 children x 6 months.

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Part V SUMMARY
Purpose of the GlucoWatch Biographer To
detect trends and to track patterns in glucose
levels as a supplement to SMBG (not to replace
SMBG). Conclusion The level of accuracy is
sufficient for detecting trends. Pilot data
shows the GWB is useful for improving glycemic
control and detecting hypoglycemia in children
and adolescents with T1DM.