1. Making the Most of Continuous Glucose Monitoring
Gary Scheiner MS, CDE
Owner & Clinical Director
Integrated Diabetes Services LLC
Wynnewood, PA
AADE 2014 Diabetes Educator of the Year
(877)

2. Making the Most of Continuous Glucose Monitoring
CGM Basics
Teaching Real-Time Use
Analyzing Downloaded Data

3. CGM Options “Personal” CGM
Medtronic 530G, 630G integrated pump w/Enlite sensor
DexCom G5
Medtronic 670G
Freestyle Libre (pending distribution)
“Professional” CGM
Medtronic iPro
Dexcom G4 Professional
Freestyle Libre Pro

4. Pump or Handheld Monitor
How They Work
Glucose sensor is inserted in subcutaneous tissue and connected to a transmitter
SC Sensor
Glucose sensor sends values to the transmitter
Transmitter
Transmitter then sends data wirelessly to a pump or handheld monitor every 5 minutes, where data can be viewed and acted upon in real-time
Pump or Handheld Monitor

5. Interstitial Fluid and “Lag Time”
Capillary glucose must diffuse into the interstitial fluid (ISF)
ISF glucose levels may lag capillary levels by 5–15 minutes
When glucose levels are stable, ISF glucose levels and capillary blood glucose levels are similar
Overall, the sensor glucose trends are more important than the absolute measurements
Plasma (V1)
(V2)
Illustration adapted from Rebrin K, et al. Am J Physiol. 1992;277:E561–E571.

6. Understanding Lag Time
Glucose Rising:
SG likely lower than actual BG
Blood
Glucose
Sensor
Glucose

7. Understanding Lag Time
Sensor
Glucose
Glucose Falling:
SG likely higher than actual BG
Blood
Glucose

8. Understanding Lag Time
Glucose Stable:
SG likely in equilibrium with BG
Sensor
Glucose
Blood
Glucose

9. What Do We Get in Real Time?
Numbers
Alerts
Trends

10. What Do We Get in Real Time?
Numbers
Alerts
Trends

11. The Numbers: How Accurate Is It Really?
MARD Compared to YSi (lab)
State-of-the-art BG Meters: %
Dexcom G4 (w/505 software), G5: %
Other Leading BG Meters: %
Medtronic Guardian: 10-11%
Freestyle Libre: %
Medtronic Enlite: %
Third, REAL-Time Trend Arrows.
One arrow up or down indicates a change of 1-2 mg/dl/min in the last 20 minutes.
Two arrows up or down indicate a change of more than 2 mg/dl/min in the last 20 minutes.
Arrows are only displayed if there has been at least a 1 mg/dl/min change in the last 20 minutes.
Patients should think about where glucose may be in 20 minutes if it continues at the same rate. 11

12. Can The Numbers Be Trusted?
Two years ago, 81% of CGM Users openly admitted to using CGM glucose values for determining insulin doses.*
Third, REAL-Time Trend Arrows.
One arrow up or down indicates a change of 1-2 mg/dl/min in the last 20 minutes.
Two arrows up or down indicate a change of more than 2 mg/dl/min in the last 20 minutes.
Arrows are only displayed if there has been at least a 1 mg/dl/min change in the last 20 minutes.
Patients should think about where glucose may be in 20 minutes if it continues at the same rate.
*T1D Exchange Research, 2015 12

13. Can The Numbers Be Trusted?
YES. but…
Not if a CGM novice
Not during sensor day 1
Not when recovering from hypoglycemia
Not in state of rapid rise or fall
Not if recent calibration off >20%
Not if acetaminopthen taken in past 4 hrs
Not if symptoms don’t match SG value
Third, REAL-Time Trend Arrows.
One arrow up or down indicates a change of 1-2 mg/dl/min in the last 20 minutes.
Two arrows up or down indicate a change of more than 2 mg/dl/min in the last 20 minutes.
Arrows are only displayed if there has been at least a 1 mg/dl/min change in the last 20 minutes.
Patients should think about where glucose may be in 20 minutes if it continues at the same rate. 13

14.  Alerts 

15. Types of Alerts Hi/Low Alert: Cross specified high or low thresholds
Predictive Alert: Anticipated crossing of high or low thresholds (Medtronic only)
Rate of Change: Rapid rise or fall
Threshold Suspend: Cross low threshold (Medtronic only)

16. Hi/Low Alert:  must balance benefit vs nuisance
 low: ≥ 80 mg/dl
 high: start very high (300?), titrate down to allowable postprandial peak
Predictive Alert:  potential for false positives
 set for short time interval (≤ 10 min)
Rate of Change:
 >3 mg/dl/min fall rate may be useful
Low Suspend (Medtronic only)
 can reduce incidence of hypoglycemia
 false positives are common

17. The Value of Alerts: Minimizing the DURATION and MAGNITUDE of BG Excursions

18. CGM Turns Mountains into Molehills

19. CGM Alerts Are Like BLOOD SUGAR BUMPERS!

20. Timely, consistent response is Key!
Act on the highs
- hydrate
- exercise
- bolus (less IOB)
2. Act on the lows
- rapid carbs

21. Decision-Making Based on Trend Information
Self-Care Choices
To snack?
To check again soon?
To exercise?
To adjust insulin?
Key Situations
Driving
Sports
Tests
Bedtime
Third, REAL-Time Trend Arrows.
One arrow up or down indicates a change of 1-2 mg/dl/min in the last 20 minutes.
Two arrows up or down indicate a change of more than 2 mg/dl/min in the last 20 minutes.
Arrows are only displayed if there has been at least a 1 mg/dl/min change in the last 20 minutes.
Patients should think about where glucose may be in 20 minutes if it continues at the same rate.

22. Adjust Boluses Based on Arrows
 Add enough to offset 60 mg/dl rise
 Add enough to offset 30 mg/dl rise
  No change to usual dose
 Subtract enough to offset 30 mg/dl drop
 Subtract enough to offset 60 mg/dl drop
Third, REAL-Time Trend Arrows.
One arrow up or down indicates a change of 1-2 mg/dl/min in the last 20 minutes.
Two arrows up or down indicate a change of more than 2 mg/dl/min in the last 20 minutes.
Arrows are only displayed if there has been at least a 1 mg/dl/min change in the last 20 minutes.
Patients should think about where glucose may be in 20 minutes if it continues at the same rate. 22

23. Simplify It For Patients!
Example:
Glucose = 180, Target = 120, Correction Factor = 30
(dose = 2u)
Carbs = 30g, I:C ratio = 10 (dose = 3u)
Usual Dose = 5u
 Add enough to offset 30 mg/dl rise (1u)
5u + 1u = 6u
 +2u
+1u
 no change
-1 u
 -2u

24. Answer This!
Betty Lou’s blood sugar is rising going into lunch. She should:
Take her usual insulin dose (based on BG and carbs)
Take her usual dose, but delay her meal
Take more than her usual dose

25. Other Applications for Trend/Curve: Hyperglycemia Treatment: (When the levee trend graph breaks)
Break within 2 hours of bolus: do not correct!
No break within 2 hours of bolus: Correct!
Third, REAL-Time Trend Arrows.
One arrow up or down indicates a change of 1-2 mg/dl/min in the last 20 minutes.
Two arrows up or down indicate a change of more than 2 mg/dl/min in the last 20 minutes.
Arrows are only displayed if there has been at least a 1 mg/dl/min change in the last 20 minutes.
Patients should think about where glucose may be in 20 minutes if it continues at the same rate. 25

26. What Can We Get From Analyzing CGM Data?
(a retrospective journey)

27. Completely Overwhelmed!
In clinics that have utilized the MiniMed Paradigm REAL-Time System in studies, certain experiences can be gained. An analysis of patients who did well experienced benefits from using it continuously or at least 90 percent of the time. Patients who have experience with insulin pump therapy seemed to benefit more than those who were new to pump therapy and therefore still learning how to optimize their insulin pump usage. Patients who looked at it frequently, almost times per day, but did not overreact to the data. Patients who had their CareLink data examined by the healthcare team, and with the help of the healthcare team, looked at trends and patterns and responses of glucose to insulin and made changes in carbohydrate to insulin ratios and basal rates. Patients who used the Bolus Wizard calculator did best and avoided hypoglycemia. It can also be said to the contrary that a lot has been learned from patients who do not benefit as much of the time: patients who did not wear the sensor at least 50 percent of the time; patients who did not trust the readings, and therefore did not look at the sensor; and patients who became extremely frustrated with nuisance alarms, causing them to stop using the sensor.
So patient behavior during wearing CGM is also a key factor to achieve a better outcome. 27

28. Objectives-Based Analysis
Are bolus amounts appropriate?
Meal doses
Correction doses
How long do boluses work?
What is the magnitude of postprandial spikes?
Is basal insulin holding BG steady?

29. Objectives-Based Analysis
Are asymptomatic lows occurring?
Are there rebounds from lows?
Are lows being over/under treated?
How does exercise affect BG?
Immediate
Delayed effects
Is amylin/GLP-1 doing the job?

30. Objectives-Based Analysis
How do various lifestyle events affect BG?
Hi-Fat meals
Unusual foods
Stress
Illness
Work/School
Sex
Alcohol

31. These Are a Few of My Favorite Stats…
Mean (avg) glucose
% Of Time Above, Below, Within Target Range
Standard Deviation
# Of High & Low Excursions Per Week

32. Case Study 1a: Fine-Tuning Meal/Correction Boluses
34-y.o. pump user
Glucose (mg/dL)
400
300
200
100
3 AM AM AM PM PM PM PM
Breakfast and lunch doses may be too low
Dinner dose appears OK
Night-snack dose clearly insufficient

33. Case Study 1b: Fine-Tuning Meal/Correction Boluses
5-year-old on MDI; levemir BID.
Dropping low 2-3 hours after dinner.
Consider decreasing dinner bolus.

34. Case Study 1c: Fine-Tuning Meal/Correction Boluses
Teenager on a pump; stays up late.
BG Rising 9pm-1am.
Consider structured night snacks with increased bolus amount.

35. Case Study 1d: Fine-Tuning Meal/Correction Boluses
Pumper, dropping low after correcting for highs during the night
Corr.
Bolus 
Consider increasing nighttime correction factor / insulin sensitivity

36. Case Study 2a: 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.
Glucose (mg/dL)
400
300
200
100
Meal

37. Case Study 2b: 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.

38. Case Study 2c: 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.

39. Case Study 3a: 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.

40. Case Study 3b: Basal Insulin Regulation
Type 1 diabetes; using insulin glargine & MDI
History of morning lows
Snacking at night and not “covering” w/bolus
Glucose (mg/dL)
400
300
200
100
3 AM AM AM PM PM PM PM
Basal dose is likely too high. Consider reducing.

41. Case Study 3c: Basal Insulin Regulation
Pump user, fasted (and no bolus) from 10am to 5pm.
BG stable 1pm-5pm.
Basal setting verified 12-4.

42. Case Study 4: Determination of Insulin Action Curve
12am am am
3-Hour Duration
4-Hour Duration
5-Hour Duration

43. Case Study 5: 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.

44. Case Study 6: Effectiveness of Amylin/GLP-1
15 mcg pramlintide
60 mcg pramlintide

45. Case Study 7: Response Curve to Different Food Types
Cereal
Oatmeal
Yogurt
Postprandial peak:
cereal > oatmeal > yogurt

46. Case Study 8: Stress Response
55 y.o. T1, pump user
No food or bolus 6am-3pm
Dentist appointment (root canal) at noon
STRESS CAN RAISE BLOOD GLUCOSE!!!

47. Case Study 8b: Responses to Lifestyle Events (exercise)
Pump user
Basal rates confirmed overnight
“yellow” night: light cardio workout prior evening
“Red” night: Lifting & cardio workout prior evening
Experiencing delayed-onset hypoglycemia from heavy workouts. Consider temp basal reduction.

48. Case Study 8c: Responses to Lifestyle Events (dining out)
Pump user
Normal fasting readings during the week, but high on weekends
Saturday Nights, Dinner Out
Delayed rise from high-fat meals.
Consider using temp basal increase.

49. YOU DON’T HAVE TO COVER ALL THIS IN ONE SESSION!!!
Statistical comparisons
Meal/Correction doses
Bolus action curve
Postprandial patterns
Basal fine-tuning
Patterns of hypoglycemia
Lifestyle effects
Medication effectiveness
YOU DON’T HAVE TO COVER ALL THIS IN ONE SESSION!!!

50. Ingredients For Success
Set up the right expectations
Encourage use at least 90% of the time
Look at the monitor times per day
Do not over-react to the data; take IOB into account
Adjust your therapy based on trends/patterns
Calibrate properly
Minimize “nuisance” alarms
In clinics that have utilized the MiniMed Paradigm REAL-Time System in studies, certain experiences can be gained. An analysis of patients who did well experienced benefits from using it continuously or at least 90 percent of the time. Patients who have experience with insulin pump therapy seemed to benefit more than those who were new to pump therapy and therefore still learning how to optimize their insulin pump usage. Patients who looked at it frequently, almost times per day, but did not overreact to the data. Patients who had their CareLink data examined by the healthcare team, and with the help of the healthcare team, looked at trends and patterns and responses of glucose to insulin and made changes in carbohydrate to insulin ratios and basal rates. Patients who used the Bolus Wizard calculator did best and avoided hypoglycemia. It can also be said to the contrary that a lot has been learned from patients who do not benefit as much of the time: patients who did not wear the sensor at least 50 percent of the time; patients who did not trust the readings, and therefore did not look at the sensor; and patients who became extremely frustrated with nuisance alarms, causing them to stop using the sensor.
So patient behavior during wearing CGM is also a key factor to achieve a better outcome. 50

51. Questions?