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					    INTRODUCTION TO CONTINUOUS
         GLUCOSE MONITORS

                               H. Peter Chase, MD
                                      Professor of Pediatrics
                                       Barbara Davis Center
                                             Aurora, CO
                                       Keystone Conference
                                    Wednesday, July 16, 2008




Barbara Davis Center for Childhood Diabetes May 2008            1
       CGM Introduction Class

• The slides from our course for families interested in
  starting CGM are available for use in your centers. They
  are on our website: www.barbaradaviscenter.org. The
  slides can then be accessed by any of the following
  methods:
• 1. Click on the “CGM Slideset” tab
• 2. In the “Online Books and Teaching Slides” page:
  http://www.uchsc.edu/misc/diabetes/books.html
• 3. In the Clinical Resources section (last entry):
   http://www.uchsc.edu/misc/diabetes/school.html



                                                         2
                 What is a CGM?
          (Continuous Glucose Monitor)
     • A device that provides “real-time” glucose readings and
       data about trends in glucose levels

     • Reads the glucose levels under the skin every 1-5
       minutes (10-15 minute delay)

     • Provides alarms for high and low glucose levels and
       trend information


     • The 3rd era in diabetes management

Barbara Davis Center for Childhood Diabetes May 2008             3
             Who Should Use a CGM?*

     1) The person and the family must both
        want a CGM
     2) A youth must be willing to wear the
        sensor (and carry the receiver)
     3) Using good diabetes care (4 BGs/day)
     4) Good support system
     5) Adequate body “real estate”
     6) Cost of CGM (RNs to elaborate)
                          *(Understanding Pumps and CGMs, p.100)
Barbara Davis Center for Childhood Diabetes May 2008               4
    Continuous Glucose Monitoring (CGM)
                  WHY?

     A. Prevention of low blood sugars (alarms)
     B. Prevention of high blood sugars (ketones)
     C. Minimize wide glucose fluctuations
     D. Behavior Modification
     E. Prevention of Complications (?)

Barbara Davis Center for Childhood Diabetes May 2008   5
  How common are glucose levels <60mg/dl
    during the night in children with T1D?

          – French (i) and Australian (ii) data showed
            approximately 50% of children with low BG
            (<60mg/dl) during the night (on NPH bid)
          – DirecNet data (one night in hospital with blood
            sugars every 30 min.)
                       A) 2001-2002: 39 of 91 (43%) low BG
                                (44% of children on insulin pumps/56% on NPH)
                       B) 2004: 14 of 50 (28%) with low BG
                                (all on insulin pumps or Lantus)


                                  i)    Beregszaszi M, et al. J Pediatr. 131, 27, 1997
Barbara Davis Center May 2008                                                            6
                                  ii)   Porter PA, et al. J. Pediatr. 13, 366, 1997
    Continuous Glucose Monitoring (CGM)
                  WHY?

  A. Prevention of low blood sugars (alarms)
  B. Prevention of high blood sugars (ketones)
  C. Minimize wide glucose fluctuations
  D. Behavior Modification
  E. Prevention of Complications (?)


Barbara Davis Center for Childhood Diabetes May 2008   7
                 “Snapshot of BG levels”




Barbara Davis Center for Childhood Diabetes May 2008   8
       Continuous Glucose Monitoring




Barbara Davis Center for Childhood Diabetes May 2008   9
         Hyperglycemia is common,
           especially after meals
     50%

     40%

     30%                                                                  Breakfast
                                                                          Lunch
     20%                                                                  Dinner

     10%

       0%
                  < 180         181 - 240 241 - 300        > 300

Barbara Davis Center May 2008                                                      10
                                       Boland et al, Diabetes Care 24:1858, 2001
     Continuous Glucose Monitoring (CGM)
                   WHY?

    A. Prevention of low blood sugars (alarms)
    B. Prevention of high blood sugars (ketones)
    C. Minimize wide glucose fluctuations
    D. Behavior Modification
    E. Prevention of Complications?

Barbara Davis Center for Childhood Diabetes May 2008   11
              Three Parts to All CGMs:*

              A. Sensor

              B. Transmitter

              C. Receiver/Monitor
                       *(Understanding Pumps and CGMs, p.103)

Barbara Davis Center for Childhood Diabetes May 2008            12
                                   A)Sensor
                                              (p.103)




Barbara Davis Center for Childhood Diabetes May 2008    13
                          B)Transmitter
                                              (p.103)




Barbara Davis Center for Childhood Diabetes May 2008    14
           C)Receiver or Monitor
                                              (p.103)




Barbara Davis Center for Childhood Diabetes May 2008    15
       What does “Calibration” mean and
            why do I need to do it?

     • Calibration is a process that gives a
       fingerstick BG value to the CGM system
       so the values will align with each other
     • Number of Calibrations vary by device
     • Best times to calibrate are when the BG
       values are stable: before meals and before
       bed
     • Do not calibrate when arrows are present
Barbara Davis Center for Childhood Diabetes May 2008   16
    What type of data will we get?

     1) “Real-time” (Immediate)

                i. Trend graphs (p.109)*

               ii. Alarms (p.110)*

               iii. Trend arrows (p.113)*
Barbara Davis Center May 2008                                     17
                                *(Understanding Pumps and CGMs)
                         i) TREND GRAPHS*




            Trend graphs – Knowing a glucose
            level is 240 mg/dl may not be as
            important as knowing the “trend.”

     *(Understanding Pumps and CGMs, p.103)
Barbara Davis Center for Childhood Diabetes May 2008
              ii) ALARMS (p.109)
        Can warn patients of current or
      projected high and low blood sugar




• Projected alarms: 10, 20, or 30 minute warning of
  impending hypo- or hyperglycemia
    (Navigator and Guardian devices)
• Threshold alarms: warning when glucose is below or
  above a set value (all devices)
Barbara Davis Center for Childhood Diabetes May 2008
              iii) TREND ARROWS (p.110)
                  Rate of Change Arrows
     Gives the up-to-the-minute glucose value and
     a rate of change arrow            Glucose rising quickly
                                                       >2 (mg/dL)/min

                                                       Glucose going up
                                                       1 to 2 (mg/dL)/min

                                                       Fairly stable glucose
                                                       -1 to 1 (mg/dL)/min

                                                       Glucose going down
                                                       -1 to -2 (mg/dL)/min

                                                       Glucose falling quickly
                                                       >-2 (mg/dL)/min

Barbara Davis Center for Childhood Diabetes May 2008
             Second type of data:
       (Retrospective, must download)

     2) Retrospective
          A. Modal Day Graphs (p.113)
          B. Pie Chart (p.114)
          C.Statistics (p.113)
                            *(Understanding Pumps and CGMs, Chapter 17, p.109)

Barbara Davis Center for Childhood Diabetes May 2008                             21
                        A) Case Study:
                      Modal Day Graphs*
    • Teenager with T1D for 9.5 years
    • Started Navigator: Sept. 2005
    • Starting HbA1c: 7.1%
    • Most recent HbA1c: 6.0%
    • Current number of low BGs per week (<60
      mg/dL or <3.3 mmol/L): 1/week
    • Three “modal-day” graphs:
                            *(Understanding Pumps and CGMs, p.113)

Barbara Davis Center for Childhood Diabetes May 2008                 22
 A) BASELINE GLUCOSE MODAL DAY:
                         i) Prior to Navigator Use




Barbara Davis Center for Childhood Diabetes May 2008   23
               A) GLUCOSE MODAL DAY
             Breakfast/Lunch Improvements
                      ii) After three months of use




Barbara Davis Center for Childhood Diabetes May 2008   24
               A) GLUCOSE MODAL DAY
                            iii) Most recent report




Barbara Davis Center for Childhood Diabetes May 2008   25
                 B) PIE CHARTS (p.114)




Barbara Davis Center for Childhood Diabetes May 2008   26
                  C) STATISTICS (p.113)




Barbara Davis Center for Childhood Diabetes May 2008   27
              USE OF CGM RESULTS:
   (To “fine-tune” insulin and diabetes management)

      i) Important not to overwhelm families

                 *** One change at a time ***

      ii) Look for patterns 2 out of 3 days

      iii) A behavior modification device  Missed
           boluses, snacking, low BGs on CGM

      iv) Good initial communication with HCP

Barbara Davis Center for Childhood Diabetes May 2008   28
                                    Questions?


     • The presentation by the nurses
       will be next.
     • You will then examine the CGMs
       from 3 companies.


Barbara Davis Center for Childhood Diabetes May 2008   29
   Part 2: CLINICAL STUDIES

• Use of CGM (The Navigator) in Clinical
  Studies of Children:
  A) Insulin Pump Study (JPediatr
  151:388,2007)
  B) Lantus Study (DiabetesCare
  31:525,2008)



                                           30
 CGM can help with glycemic control
A) 30 Pump Patients Using Navigator x 13 weeks*

 N                             30
 Mean Age                      11.2 yr
 T1D duration                  5.8 years
 Female                        40%

 HbA1c                         Initial     13 wks
                               7.1±0.6%    6.8±0.7%
                                           (p=0.02)

          *DirecNet J Pediatri 151,388,2007           31
                                                         HbA1c

            8.5
                                                                          Baseline A1c 7.0%
                                                                          Baseline A1c >7.0%
            8.0

                                  N=15
            7.5
                                                                    *
HbA1c (%)




                                                      N=15                                               N=12
                                                                        N=15
            7.0

                                                                                                  N=13
            6.5            N=15                                                                    §
                                               N=15          N=13


            6.0


            5.5

                    Baseline              Week 7               Week 13                        Week 26
              Black dots denote mean values and boxes denote median, 25th and 75th percentiles.
                                                                                                          32
              * p=0.004   vs. baseline; § p=0.002 vs. wks 9-13.
                                         Percentage of Navigator Glucose Values
                                                    in Target Range
                                   90%
                                                                                      Baseline A1c 7.0%
Percent in target range (71-180)




                                                                                      Baseline A1c >7.0%
                                   80%


                                   70%                                                                N=11
                                                                N=15                       N=13
                                                   N=15                      N=13                                  N=11
                                          N=13
                                   60%
                                                                                                  N=11
                                                                                       N=15                  N=9
                                                            N=15         N=15                                             N=11
                                   50%
                                                 N=14

                                   40%


                                   30%

                                         Baseline         Wks          Wks          Wks       Wks        Wks          Wks
                                                          1-4          5-8          9-13      14-17      18-21        22-26
                                                                                                                       33
                               Percentage of Navigator Glucose Values
                                          Below 70 mg/dL
                         14%

                                                                               Baseline A1c 7.0%
Percent below 70 mg/dL




                         12%
                                                                               Baseline A1c >7.0%

                         10%


                         8%
                                    N=13                                              N=13                   N=11
                                                                  N=13
                         6%                N=15       N=15                                          N=11

                                                                                                                    N=11
                         4%                                                    N=15
                                                    N=15                                     N=11
                                                                 N=15
                         2%            N=14                                                            N=9


                         0%

                               Baseline       Wks          Wks          Wks       Wks               Wks      Wks
                                              1-4          5-8          9-13      14-17             18-21    22-26
                                                                                                              34
B) Lantus Subjects using CGM*
N                             27 (23 completed)
Age                           11.0 ± 3.9 yr
Female                        14 (52%)
Caucasian                     25 (93%)
HbA1c                         7.9 ± 1.0%
T1D duration                  4.0 ± 3.1 yr
MDI Regimen
  Glargine + RAIA*            21 (78%)
  Glargine + RAIA* + NPH       5 (16%)
  Other                        1 ( 4%)
* DirecNet: Diabetes Care 31:525, 2008            35
                  Lantus Subjects using CGM
                   Results – Glycemic Control

            9.5                        Baseline A1c > 7.5%
                                       Baseline A1c ≤ 7.5%
            9.0

            8.5
                                             *
HbA1c (%)




            8.0

            7.5

            7.0                         **
            6.5

            6.0
                                                  * p = 0.02
            5.5                                  ** p = 0.03
                                                               36
                   Baseline   Week 7   Week 13
                               Lantus Subjects using CGM
                                   Results – Glycemic Variability

                             180                                   Baseline A1c > 7.5%
                                                                   Baseline A1c ≤ 7.5%
Mean Amplitude of Glycemic
 Excursion (MAGE, mg/dL)




                             160

                                                                              *
                             140


                             120

                                                                         **
                             100
                                                                              * p = 0.004
                                                                              ** p = 0.17
                              80
                                                                                            37
                                    Baseline   Wks 1-4   Wks 5-8      Wks 9-13
       Lantus Subjects using CGM
                    Conclusions

• Use of the Navigator CGM was associated with an
  improvement in glycemic control without an
  accompanying rise in hypoglycemia

• Glycemic variability decreased with use of the
  Navigator

• Subjects and parents reported high overall
  satisfaction with the Navigator and did not
  demonstrate deterioration in quality of life during 3-
  month use

• CGM are tolerable and effective in children using MDI
  regimens                                                 38
CGM Influences on Glucose Levels

 Blinded vs Non-Blinded CGM Tracings:
                                 p-value
 • 21% less time <55 mg/dl       <0.001
 • 23% less time >240 mg/dl      <0.001
 • 26% more time in target       <0.001
           (81 – 140 mg/dl)
 (Garg et al, Diabetes Care 27:1922,2004)
                                            39
   COMMON MISCONCEPTIONS OF CGM
              (QUIZ)

   1) “If I use CGM, I do not have to do BG checks anymore.”




Barbara Davis Center for Childhood Diabetes May 2008     40
   COMMON MISCONCEPTIONS OF CGM

  2) “The starting of CGM will make diabetes management a
  breeze – so simple!”




Barbara Davis Center for Childhood Diabetes May 2008   41
   COMMON MISCONCEPTIONS OF CGM

 3) “The use of CGM will fix the diabetes – all blood sugars
 will be perfect.”




Barbara Davis Center for Childhood Diabetes May 2008      42
   COMMON MISCONCEPTIONS OF CGM

  4) “My CGM values should match my BG values.”




Barbara Davis Center for Childhood Diabetes May 2008   43
   COMMON MISCONCEPTIONS OF CGM

  5) “The alarms will catch every low or pending low so I
  don‟t need to worry about lows anymore.”




Barbara Davis Center for Childhood Diabetes May 2008        44
 CLOSED LOOP (BIONIC) PANCREAS
                 “The Future”
i) Will probably come in parts
ii) JDRF supporting algorithm development
iii) Should reduce glucose highs, lows, and
     fluctuations
iv) Will probably be more realistic than islet cell
    transplant
v) FDA and medical insurance approvals (as with
   CGM) will be critical
                                                      45
Q. Why combine insulin pumps (CSII) and
  Continuous Glucose Monitors (CGM)?
                    (p121)

A: “They complement each other tremendously
and provide the most „state of the art‟ diabetes
care available.”

     The CGM helps with:
        •Cannulas dislodging
        •Missed food boluses
        •Hypoglycemia
        •Corrections                          46
           Our Initial Data:

1. Two oral presentations at ADA in June,
   2008 (Abstract # 230-OR and 42-OR).
2. Our emphasis: Preventing severe
   hypoglycemia at night.
3. This may be the first part of a closed loop
   system acceptable to the FDA.
4. We have shown that 80% of pending
   lows can be predicted.
5. Safety remains the primary goal.
                                             47
“Now let me get this right, Dr. Chase…
   You want the elves to make an
         artificial pancreas?”
              THANK YOU                  48

				
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