Making the Most of Continuous Glucose Monitoring
Gary Scheiner MS, CDEOwner & Clinical Director
Integrated Diabetes Services LLC
Wynnewood, PA
“Dean”
Type-1 University
www.type1university.com
Making the Most of Continuous Glucose Monitoring
1. What Information Is Available
2. How to Use Immediate Data
3. How to Use Intermediate Data
4. What Can Be Learned from Retrospective Analysis
5. Optimizing CGM System Performance
Sensor Daily Overlay
Report Options:Medtronic Carelink Personal
Sensor Overlay By
Meal
3
• Sensor tracing & BG entries
• Basal & bolus delivery
• Carbohydrate, exercise &
logbook entries
Daily Summary Layered Report:
Report Options:Medtronic Carelink Personal
4
• Avg, SD, Hi/Low
• # Hi/Low Excursions, AUC
• % Time above, below, within target range
Statistical Summary
Report Options:Medtronic Carelink Personal
5
Hourly Statsw/data table for each hour
Glucose TrendIncludes event entries
Report Options:DexCom DM3*
6
* Dexcom 7+ System not FDA approved for use in children under age 18 in the U.S.
BG Distribution% high, low, normal for each segment of the day
Modal DayCustomizable
date range
Report Options:DexCom DM3
7
Success Report
Report Options:DexCom DM3
16 Jan - 15 Apr 10 16 Apr - 15 Jul 10 ChangeA1c % 0.0 % 0.0 % N/A
Mean Glucose 191 164 -14 %
Standard Deviation 65 64 -2 %
% in Hypoglycemia (39-55 mg/dL)
0 1 N/A
% in Low (55-70 mg/dL) 1 3 200 %
% in Target (70-160 mg/dL) 33 48 45 %
% in High (160-240 mg/dL) 46 36 -22 %
% in Hyperglycemia (240-401 mg/dL)
20 12 -40 %
Days Sensor Used 22 91 314 %
12 am 1 am 2 am 3 am 4 am 5 am 6 am 7 am 8 am 9 am 10 am 11 am16 Jan - 15 Apr 10 206 199 204 208 206 198 179 169 166 172 181 19616 Apr - 15 Jul 10 165 167 170 168 163 156 148 147 152 164 175 176
Changes in control: week-to-week, month-to-month, or quarter-to-quarter
Breakdown by hour, with averages
8
Report Options:Freestyle Navigator/Copilot
Modal Day Report
Customizable by date range, day of week
Glucose Line Report
Stats Report
Broken down by phase of the day 9
Report Options:Freestyle Navigator/Copilot
Logbook Report(Sensor BG q10 minutes) 10
What Do We Get in Real Time?
Trends
Alerts
Numbers
Decision-Making Based on Trend Information
• Self-Care Choiceso To snack?o To check again soon?o To exercise?o To adjust insulin?
• Key Situationso Drivingo Sportso Testso Bedtime
Bolus AdjustmentBased on Trend Information
• BG Stable: Usual Bolus Dose
• BG Rising Gradually: bolus slightly*
• BG Rising Sharply: bolus modestly**
• BG Dropping Gradually: bolus slightly*
• BG Dropping Sharply: bolus modestly**
* Enough to offset 25 mg/dl (1.5 mmol/l)
** Enough to offset 50 mg/dl (3 mmol/l)
Immediate Info: Hypoglycemia Alerts
• Predictive Hypo Alert or Hypo Alert & recovering: Subtle Treatment • 50% of usual carbs
• Med-High G.I. food
• Hypo Alert & Dropping: Aggressive Treatment• Full or increased carbs
• High G.I. food
vs
Types of Alerts
• Hi/Low Alert: Cross specified high or low thresholds
• Predictive Alert: Anticipated crossing of high or low thresholds
• Rate of Change: Rapid rise or fall
The Value of Alerts:
Minimizing the DURATION and MAGNITUDE of BG Excursions
CGM Turns Mountains into Molehills
Uniform Response is Key!
1. Fingerstick
2. Act on the Fingerstick
Setting Alerts
• Hi/Low alert thresholds are not BG target ranges
• Balance need for alerts against “nuisance factor”
• Predictive alerts lose value the further the advance warning (keep below 10 min)
• Rate of FALL alerts helpful for long-term hypo prevention (>3 mg/dl/min) (.17)
LOW: 80 mg/dl (4.5 mmol)(90/5+ if hypo unaware)
HIGH: 300 mg/dL (18 mmol)(lower progressively toward 180/10)
NOT RECOMMENDED: Low 70 (4)NOT RECOMMENDED: High 140 (8)
Initial Hi/Low Alert Settings
Special Alert Settings
• Young children (higher, wider range)
• Hypoglycemia unawareness, high-risk professions (higher hypo setting)
• Pregnancy (lower, narrower range)
• HbA1c of 11.0% (higher initially)
The Numbers:Ballpark Estimates
+/- 20% if >80 (4.4)
+/- 20 mg/dl if <80 (+/- 1 mmol/l if < 4.4)
Can The Numbers Be Trusted?
• Not during first 1-2 cycles of using the system
• Not during the first 12-24 hrs after sensor insertion
• If BG Stable
• If Recent calibrations in-line
• If No recent alarms
Specific Insights to Derive(a purely retrospective journey)
CGM Data Analysis Tools
Hardware/Software
• Medtronic: – Internet Access to Carelink– Carelink USB Adapter
• Dexcom*: – PC, DM3 Software– Connector Cable
• Color Printer* Dexcom 7+ System not FDA approved for use in children under age 18 in the U.S.
Before You Analyze, Qualify. Before You Analyze, Qualify. • Were sufficient calibrations performed?
• Did the calibrations match the CGM data reasonably well?
• Was the data mostly continuous?
• Was the time/date set correctly?
26
Before You Analyze, Qualify. Before You Analyze, Qualify.
MAD = 28%
Abnormal Artifact
gaps & inaccuracy
27
1. Are bolus amounts appropriate?– Meal doses– Correction doses
2. How long do boluses work?
3. What is the magnitude of postprandial
spikes?
4. Is basal insulin holding BG steady?
Objectives-Based Analysis
5. Are asymptomatic lows occurring?– Are there rebounds from lows?– Are lows being over/under treated?
6. How does exercise affect BG?– Immediate– Delayed effects
7. Is amylin/GLP-1 doing the job?
Objectives-Based Analysis
8. How do various lifestyle events
affect BG?– Hi-Fat meals– Unusual foods– Stress– Illness– Work/School– Sex– Alcohol
Objectives-Based Analysis
Reports to Focus onReports to Focus on
• Summary Statistics
• Modal Day / Overlay Graphs
• Individual Day Details
31
These Are a Few of These Are a Few of My Favorite My Favorite
Stats… Stats…
Mean (avg) glucose
% Of Time Above, Below, Within Target Range
Standard Deviation
# Of High & Low Excursions Per Week
32
Case ExamplesCase Examples(the “retrospective journey”)
Case Study 1: The “Dark Side of the Moon”
• Type 2; using glargine and metformin• Fasting readings OK; HbA1c elevated
BG rising & staying high after meals. Consider meglitinide, exenatide, mealtime bolus insulin
BG rising & staying high after meals. Consider meglitinide, exenatide, mealtime bolus insulin
3 AM 6 AM
Glu
cose
(m
g/d
L)
400
300
200
100
0
9 AM 12 PM 3 PM 6 PM 9 PM
Case Study 2a: Fine-Tuning Meal/Correction Boluses
Breakfast and lunch doses
may be too low
Breakfast and lunch doses
may be too low
Dinner dose appears OK Dinner dose appears OK
Glu
cose
(m
g/d
L)
400
300
200
100
0
3 AM 6 AM 9 AM 12 PM 3 PM 6 PM 9 PM
Night-snack dose clearly insufficient
Night-snack dose clearly insufficient
• 34-y.o. pump user
Case Study 2b: Fine-Tuning Meal/Correction Boluses
Dropping low 2-3 hours after dinner.
Consider decreasing dinner bolus.
Dropping low 2-3 hours after dinner.
Consider decreasing dinner bolus.
• 5-year-old on MDI; levemir BID.
Case Study 2c: Fine-Tuning Meal/Correction Boluses
BG Rising 9pm-1am.
Consider structured night snacks with increased bolus amount.
BG Rising 9pm-1am.
Consider structured night snacks with increased bolus amount.
Teenager on a pump; stays up late.
Case Study 2d: Fine-Tuning Meal/Correction Boluses
• Pumper, dropping low after correcting for highs during the night
Corr.Bolus
Consider increasing nighttime correction factor / insulin sensitivity
Consider increasing nighttime correction factor / insulin sensitivity
Case Study 3a: Postprandial Analysis
• Young adult on MDI. • HbA1c are higher than expected based on SMBG• Tired and lethargic after meals
Significant postprandial spikes (300s). Consider pramlintide before meals.
Significant postprandial spikes (300s). Consider pramlintide before meals.
Glu
cose
(m
g/d
L)
400
300
200
100
Meal
Meal
MealMeal
Case Study 3b: Postprandial Analysis
• Pump user, usually bolusing right before eating. • Potatoes w/dinner most nights.
Spiking primarily after dinner.
Consider lower g.i. food or pre-bolusing.
Spiking primarily after dinner.
Consider lower g.i. food or pre-bolusing.
Case Study 3c: Postprandial Analysis
• Pump user, 6 months pregnant• Pre-bolusing (15-20 min) at most meals.
Spiking primarily after breakfast.
Consider “splitting” breakfast or walking post-bkfst.
Spiking primarily after breakfast.
Consider “splitting” breakfast or walking post-bkfst.
Case Study 4a: Basal Insulin Regulation
• Pump user, 6 months pregnant• Generally not eating (or bolusing) after 8pm.
BG rising 1am-6am.
Consider raising basal insulin 12am-5am.
BG rising 1am-6am.
Consider raising basal insulin 12am-5am.
Case Study 4b: Basal Insulin Regulation
Glu
cose
(m
g/d
L)
400
300
200
100
0
3 AM 6 AM 9 AM 12 PM 3 PM 6 PM 9 PM
Basal dose is likely too high. Consider reducing.Basal dose is likely too high. Consider reducing.
• Type 1 diabetes; using insulin glargine & MDI• History of morning lows• Snacking at night and not “covering” w/bolus
Case Study 4c: Basal Insulin Regulation
Glu
cose
(m
g/d
L)
400
300
200
100
0
BG dropping after bolus action completed. Consider reducing basal rates early morning & late afternoon.
BG dropping after bolus action completed. Consider reducing basal rates early morning & late afternoon.
• Pump user, frequent lows before breakfast and dinner.
Case Study 5: Determination of Insulin Action Curve
3-Hour Duration
5-HourDuration
4-Hour Duration
12am 3am 6am
Case Study 6: Detection of Silent Hypoglycemia
• Type1 college student; on pump
• Frequent fasting highs (9-10 AM). Wanted to raise overnight basal rates.
Dropping & rebounding during the night. Consider decreasing basal in early part of night.
Dropping & rebounding during the night. Consider decreasing basal in early part of night.
Case Study 7: Effectiveness of Pramlintide/Exenatide
• 15 mcg pramlintide
• 60 mcg pramlintide
Case Study 8: Response Curve to Different Food Types
Postprandial peak: cereal > oatmeal > yogurt
Postprandial peak: cereal > oatmeal > yogurt
CerealOatmealYogurt
Case Study 9: Immediate Responses to Unusual Events
• Type 1 diabetes; pump user
• 40 years old; athletic
• Handsome, excellent speaker
• Gets flat tire; eats 15g carbs to prepare for tire change
• Spare is flat too!!
STRESS CAN RAISE BLOOD GLUCOSE… A LOT!!!STRESS CAN RAISE BLOOD GLUCOSE… A LOT!!!
• Late for meetingG
luco
se
(mg
/dL
)
400
300
200
100
0
9 AM 12 PM 3 PM 6 PM 9 PM
Case Study 10a: Delayed Effects
Experiencing delayed-onset hypoglycemia from heavy workouts. Consider temp basal reduction.Experiencing delayed-onset hypoglycemia from
heavy workouts. Consider temp basal reduction.
• Pump user• Basal rates confirmed overnight• “yellow” night: light cardio workout prior evening• “Red” night: Lifting & cardio workout prior evening
Case Study 10b: Delayed Effects
Delayed rise from high-fat meals. Consider using temp basal increase.Delayed rise from high-fat meals.
Consider using temp basal increase.
Saturday Nights, Dinner Out
• Pump user• Normal fasting readings during the week, but high on
weekends
Your Turn!
• What conclusions might you draw?
• What recommendations would you give?
Your Turn!
• What conclusions might you draw?
• What recommendations would you give?
Optimizing CGM System Performance
• Calibration
• Sensor & Site Care
• Signal reception
• Ingredients for success
• Calibrate at times when blood glucose (BG) is stable (fasting, pre-meals)*
• Avoid calibrations during times of rapid glucose change*– Post meal
– UP or DOWN arrows are displayed
– In the period following a correction with food or insulin
– During exercise
* Not required w/Dexcom system
Optimal Calibration
• Calibrate before bedtime to avoid alarms during the night
• Use good SMBG technique– Proper coding
– Clean hands
– Sufficient blood sample
– Fresh strips
• USE FINGERSTICKS
• Enter the calibration immediately after the fingerstick (Dexcom, Medtronic systems)
Calibration
The Sensors• Storage
– Refrigeration preferred (but not required)
– OK to use 1-2 months past expiration
• Site Selection– “Fleshy” areas
– At least 2” Away from insulin infusion
– Avoid tight clothing areas, scars, bruises, lipoatrophy
– Rotate sites
The Sensors• Timing
– Allow adequate “wetting” time (Medtronic)– Put sensor in the night before connecting the transmitter
(Medtronic)
• Bleeding/Irritation– Slight bleeding OK
– Profuse bleeding: remove
– Remove introducer needle at proper angle
The Sensors• Adhesive
– Completely cover the Transmitter & Sensor (Navigator & Medtronic systems)
– Check sensor daily for loose tape
– Apply extra tape over sensor & transmitter if tape patch begins to “curl” around edges
• Site Irritation– Watch for redness, swelling, tenderness– Remove sensor with prolonged irritation (>1 hour)
Signal Reception• Heed transmitter ranges
– Medtronic: 6 ft.– Dexcom: 5 ft.– Navigator: 10 ft.
• Signals do not travel well through water
– Wear receiver on same side of body as sensor
• Keep receiver very close while charging (Dexcom)
• Charge transmitter fully every 6 days (Medtronic)
Ingredients For Success• Have the right expectations
• Wear the CGM at least 90% of the time
• Look at the monitor 10-20 times per day
• Do not over-react to the data; take IOB into account
• Adjust your therapy based on trends/patterns
• Calibrate appropriately
• Minimize “nuisance” alarms
Questions?
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