Utilizing your CGMS to the Max Stephen W. Ponder MD, FAAP, CDE
Jun 26, 2015
Utilizing your CGMS to the MaxStephen W. Ponder MD, FAAP, CDE
What can a CGMS help you do?Continuous Glucose Monitoring System
• Prevent after meal BG spikes• Correct low & high BG more accurately• Prevent/minimize severe low blood sugars• Teach you how to sense subtle shifts in BG• Reduce the fear of lows, especially at night• Lower the A1C levels• Help to make diabetes work for YOU• Feel more “normal” (perhaps even confident)
What I will not be discussing…• Costs of different CGM devices
– That depends on your insurance– There is a cash price too
• How to purchase a CGM device– Operators probably standing by now– Need Rx to get insurance to consider
paying
• How to insert or start up a CGM– There are trainers and apps for that
Principles of advanced CGM use1. A CGM is no better or
worse than the person wearing it.
2. If you can measure it, you can predict it.
3. Flux and drift happen… manipulate them!
4. Keep your eye on your line.5. The trend is your friend6. Learn lag limits; be patient
7. Zero in on your zone8. Master micro-dosing9. Factor in glycemic inertia
and insulin momentum10. Don’t let “good enough”
be the enemy11. Calibrate carefully12. CGM as “sugar surfing”
or “day trading”
“Chance favors the prepared mind” Louis Pasteur
• Estimates sugar level from interstitial fluid
• Calibrated with fingerstick blood sugar levels at least twice daily
• Readings provided every 1 to 5 minutes
• Drift and imprecision are possible
24 hour glucose plot – A1c 5.7%
1st Rule of CGM:Your blood sugar levels are unique.Trends and patterns are what’s important
Diabetes control exists largely in the momentNo two days are ever the same…
Each day is unique…
“You can never step into the same river; for new waters are always flowing on to you.” Heraclitus of Ephesus
8 versus 1440 “decision points”
7:03 115
9:33 129
12:15 95
3:34 131
6:12 168
9:49 107
11:53 114
3:05 132
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CGM is like shining a flashlight in a dark room of moving objects
Meters are commodity items“a commodity is the generic term for any marketable item
produced to satisfy wants or needs”
• The best BG meter is the one you’ll use
• $10.41 for 50 strips (Medicare 2013 rate)
• Lancing devices (avoid the nerves)
• Ketone meter (get one!)
ISO and FDA allowable errors
• 20% for 95% of BG values 75 mg/dl
• 15 mg/dl for 95% of BG values 75 mg/dl
• 5% “outliers” of ANY DEGREE of magnitude
“Glycemic Roulette”?
Diabetes Spectrum Volume 25, Number 3, 2012ISO 15197 Standards for SMBG
95 mg/dl
114 mg/dl
76 mg/dl
223 mg/dl
52 mg/dl
95% of the time
Oops!
Oops!
5%
5%
Calibration advice
• A CGM’s accuracy is no better than its calibration. • So…minimize variance whenever possible• Calibrate (if possible) when things are steady• Wash hands; get proper sized blood sample
(repeat if needed)• If you calibrate when high or low, do some more
later when back “in your zone”• You can over-calibrate too.
Remember: D-care is about managing sugar…
FLUXdrift
(Glucose production – Glucose disposal) = FLUX
Here is a picture of FLUX
Non-diabetic persons
Sugarlevel
In Out
Why do blood sugar levels shift all the time?
How much sugar is in the bloodstream for a 100 mg/dl BG level?
Human circulatory system
75 kg man(5.1 grams)
25 kg girl(1.75 grams)
50 kg boy(3.45 grams)
= 4 gram glucose tab
present
past future
REACTIVE PROACTIVE
Actions
Omissions
Actions
Omissions
static vs. dynamic diabetes carestatic• Actions predetermined• Minimal to no flexibility:
RIGID• Outcomes don’t
immediately affect subsequent actions
• Easy to teach/learn• Less time-intensive• Favors concrete thinking• Less motivation needed
dynamic• Actions are dependent on
situation/circumstance• Flexible and adaptable• Outcomes influence
subsequent actions• Training needed, plus
ongoing reinforcement• More time intensive• Favors problem-solving• Requires motivation
Ways to use RT-CGM technology
“Burglar alarm” “Surveillance system ”
Set “actionable” thresholds• Upper/Lower limits
– 80 mg/dl and 140 mg/dl– 90 mg/dl and 180 mg/dl
• Rates of change– Up or down arrows
• Factor in recent/current/future events as you are able
• Test your skills, experiment a little within reason
A pancreas can’t predict the future
• It just can act very fast so it doesn’t have to.
• Can shut off insulin immediately
• Can release preformed insulin
• Insulin released can start working in minutes
• Can respond to rates of change in sugar levels
Soldier: Come on. Let me show you.Soldier: The secret to this game is no matter what happens,Soldier: never, ever take your eye off the ball.Gump: All right.Gump: For some reason, ping-pong came very natural to me.
Traits of effective CGM users• Wear it all the time• Check trend line often• Work the “lag” times
– FOOD– INSULIN– SENSOR
• Not afraid to experiment• Not expecting perfection
Penny stock day trading strategyCGM - glycemic “day trading” tool
“sugar surfing”
BG awareness vs. alarm fatigue• Set reasonable alarm
thresholds– Depends on your goals
• Avoid high spikes?• Avoid lows?• Toddler? Child? Teen? Adult?
• Make sure you can hear/sense the alarm
• Anticipatory action can minimize alarms
Living with a CGM
• Keeping up with receiver (if not part of pump)• Keeping up with meter/strips/lancing device• Sensor unit size and longevity (recycling)• Showering/bathing/changing clothes• Taping and securing• Air travel (security and seating)• Acetaminophen can cause “headaches” (Dex)• Charging up/downloading• Logging events
Taping tips
Two week site before taping
Site after 32 days
Bruise from CGM sensor
Sensor depths
Medtronic Abbott
Sensor after 32 days
Dexcom G4
Day in the life…
Another in range day
A nice day…
A nice day…BUT…
7 units
5 units 3 units
Pasta
J
“Fried-food revenge” and correction
Fried food earlier in evening @ 8PM
BG = 1946 unit correction @ 7AM
BG = 115 in 3 hours
“Revenge of the Ribeye” and “The Insulin Strikes Back”
SLOW RISE
BG 167: 4 units
CORRECTION
LAG
2-3h
Slow BG rise from protein-fat laden meal
Slow overnight rise and early AM correction
Correction at 2:45 AM after slow post dinner rise with 5 units
5 units
~ 2 hours
Overnight rise, correction and meal
Steady in-range BG trend
Overnight basal testing
Overnight basal in range (glargine)
Overnight in range!
Overnight control in range
Basal testing…
Overnight basal control - Lantus
Time to correct
> 2 hours
Corrections take time
Time to reach 100 mg/dl (at ~ 4 mg/dl/min)
minutes
Blo
od s
ugar
180
260
340
420
4 mg/dl/min
Fine tuning a correction…
62 mg/dl
8gm
Timing 101 – 20 min. match
Insulin
Food
Timing 101 – 45 min. mismatch
Insulin
Food
“THE TREND IS YOUR FRIEND”CHECKING INSULIN BOLUSES WITH CGM
6 pm 8 pm 10 pm
300
200
100
60
Carb bolus Correction bolus
6 pm 8 pm 10 pm
Goal: green lines
Learning from the Line Graph – Effect of Exercise
2p 4p
70140
210
350
280 Bike ride – 60 minutes
E
2p 4p
70140
210
350
280
E
No insulin adjustment w/ basal rate reduction
CHO
Learning from the Line Graph – Correction dose
70140
210
350
280
8a 10a
“Stacked” insulin
I I 70
140
210
350
280
Blood glucose: 212 mg/dl
Correction dose: 5.5 units
I
Proper correction
Blood glucose: 212 mg/dl
Correction dose: 5.5 units
Correction dose: 3.5 units
12p 8a 10a 12pCHO CHO
Learning from the Line Graph – Insulin Timing
8a 10a
70140
210
350
280
8a 10a
70140
210
350
280
TodayYesterday
Insulin bolus: 7:30 AM
Breakfast: 7:30 AM
Insulin bolus: 7:10 AM
Breakfast: 7:30 AM
MI MI
Learning from the Line Graph – Effect of Food
8a 10a
70140
210
350
280
8a 10a
70140
210
350
280
TodayYesterday
Bagel Breakfast Oatmeal breakfast
M I M I
Don’t Stack your Insulin!
Slide courtesy of Jen Block RN, CDE and Stephen Ponder MD CDE
Learning from the Line Graph – What would you do?
4:30 pm 6:30 pm
70
140
210
350
280
1. What did I do?
2. What am I doing?
3. What will I be doing?
4. What do I need to do?
Learning from the Line Graph – What would you do?
12:30 pm 2:30 am
70
140
210
350
280
1. What did I do?
2. What am I doing?
3. What will I be doing?
4. What do I need to do?
Learning from the Line Graph – What would you do?
12:30 pm 2:30 pm
70
140
210
350
280
1. What did I do?
2. What am I doing?
3. What will I be doing?
4. What do I need to do?
What would you do next?
How would you categorize this?
4 day non-diabetic CGM plot
Turnaround Time : glycemic inertia
Corrections may need to be adjusted 10-20% to compensate
Goal: Try to stay between the lines
As readings improve, lower the glucose for the upper alert
112 mg/dl to 78 mg/dl after 1.5 units by injection on a “steady” BG baseline
1.5 units
~ 2 hours
Correction
~ 80m
~ 25m
5 units @ 5:43AM; 25 gm CHO @ 6:23AM
5 units
Meal(25 gm CHO)
40 minutes
Calibrate during a steady baseline
Calibrating with extreme BG levels can distort accuracy. Try to calibrate within your desired target zone range.
“Microcarbing” with CGM monitoring
2 gm CHO
Before 2 grams CHO After 2 grams CHO
Blood sugar correction 160 mg/dl to 100 mg/dl in 2 hours with 4 units insulin lispro by injection
4 units
~ 2 hours
Correction: 151 mg/dl to 103 mg/dl with 2 units insulin lispro after walk
2 units
~ 2 hours
Optimal lunch coverage
5 units
Stopping sugar spikes
3 units (5:32AM)
Meal(5:48 AM)
Calibrate during a steady trend
Calibrate on a steady line whenever possible
103 mg/dl
97 mg/dl
Steady
Calibrate during a steady trend
Correction and meal
6 units (161 mg/dl)
Meal(26 gm CHO)
~ 45m126 mg/dl
Correction with 20 grams carbs
20 gm CHO
Skipped data (out of range?)
Sensor starting to lose integrity at 32 days
14 days of use32 days of use
Sensor confusion?
Sensor confusion?
Duration of insulin effect can be determined here
~ 4 hours
IOB after 6 units and fried meal
6 units
3.5-4 hours 2 units
WalkFried Meal
Walking down a trend
2 units
1 hr walk
Wait for the bend!!
6U @146 mg/dl Eat here
@132 mg/dl
45 minutes
Wait for the “bend”!
Stress effect
Microbolus at 7:55AM when BG was 151 mg/dl took 2 units (after surgery)
Although subtle, this can be “felt”
First…figure out your favorite foods
Why do lows happen at night?
• Hormonal patterns• Lower insulin need• Insulin peaks?• Post-exercise effect• Snacking stacking?
Lower overnight insulin/add snack
Don’t pass up an opportunity to correct a high (or low) BG
• Choose what you consider “actionable”?
• BG above or below chosen thresholds
• Consider recent and impending actions
• Check your results with BG levels
• Repeat as necessary
Curb your liver!
• The liver makes as well as stores sugar
• A proper insulin level “calms down” the liver
• Aim for an in-range sugar level (<120 mg/dl)
upon waking up each day
Check your targets often• Make sure you hit
your target “zone” sugar (± 30 mg/dl)
• Rapid-acting insulin results are best examined at 2-3 hours
• Results should feedback to the next attempt
“Practice makes better”
D-teens count carbs POORLY
23%
clinical dietitian (n.)
1. A person specializing in medical nutrition therapy.
2. An underappreciated and underpaid member of the diabetes team.
3. Someone who can help your left brain
We have > 60,000 thoughts daily
• Groups of thoughts comprise decisions
• The typical non-D person makes ~ 250 decisions a day about food
• How many more food choices does a PWD/CWD make?
“What are we doing for dinner, dear?”
Eat at home
“You can delegate authority but you can’t delegate
responsibility”
Do 2 RN’s = 1 kid?
=
Ok? Ok to me!
Concrete thinkers* can’t…
1. Consider a hypothesis2. Consider multiple
possibilities in a scenario
3. Systematically solve a problem
4. Use combinatorial logic
*Lasts until 15-17 years of age*25% of adults are concrete thinkers.
Diabetes CONTROL results as much (if not more) from what you
choose NOT TO DO as it results from what you choose TO DO
Principles of advanced CGM use1. A CGM is no better or
worse than the person wearing it.
2. If you can measure it, you can predict it.
3. Flux and drift happen… manipulate them!
4. Keep your eye on your line.5. The trend is your friend6. Learn lag limits; be patient
7. Zero in on your zone8. Master micro-dosing9. Factor in glycemic inertia
and insulin momentum10. Don’t let “good enough”
be the enemy11. Calibrate carefully12. CGM as “sugar surfing”
or “day trading”
Questions?