Stephen W Ponder MD FAAP CDE Scott amp White Clinic Temple Round Rock and College Station Perfection not possible Reality what IS possible The diabetes care Gap Generally speaking diabetes self care is the result of the perfect minus the reality We ID: 533505
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Slide1
Boluses, basals and corrections – Getting the doses right
Stephen W. Ponder MD, FAAP, CDEScott & White ClinicTemple, Round Rock and College StationSlide2
Perfection
(not possible)Reality
(what IS possible)
-
=
The
diabetes
care
“Gap”
Generally speaking, diabetes self care is the result of the “perfect” minus the “reality”. We can (at best) only control our “reality”. Perfection in diabetes self care is not possible. Therefore, we must try to accept the size of the gap. Gaps shrink and expand. So…by this thinking… are you OK with the current size of your “gap”?Slide3
Ponder’s
Pumping PrinciplesQuality
diabetes self-care is more about the PROCESS than it
is
about OUTCOMES
Technology changes; people don’t
Self-consistency is a
virtue
Everyone’s blood sugar fluxes; seek out patterns in the
chaos
Success
is always a relative thingDon’t ever be afraid to start over
An insulin pump is no better or worse than the human being attached to itMaster carb counting well BEFORE pumpingAge is not a limiting factor for a pumpGarbage in, garbage out: beware of the “pump and dump” phenomenonThe best pump doctor acts as a coach Simple is a good place to start, but pumping skills MUST advance over timeSlide4
Why should I care about after meal blood sugar levels?Slide5
180
100
Pre-meal
2 hr
glucose
140
220
Pre-meal
7%
5%
6%
8%
HbA1c
Vascular system
chronic inflammation
95
115
?
Postmeal Blood sugars, A1c and CV Risk
Goal: improve post-meal control: BG < 180 mg/dlSlide6
Before meal sugar
After meal sugarSlide7
5 cardinal concepts to understand
Target (range)Basal rate(s)Insulin:CHO ratio(s)Correction factor(s)
Insulin on board (IOB)
A number or range
Start with 1 rate
Start with 1 I:CHO
Start with 1 CF
3.5 to 5 hours (4)Slide8
Diabetes is best approached 1 day at a timeSlide9
Diabetes care is a
process, not an action
It has purpose, meaning or directionIt has a logical structure or orderSteps are mostly measureableIt has a goal, outcome or resultSlide10
Duration Of Carb ActionOr…UNDERSTAND YOUR TARGETS
Most carbs have most of their affect within 1 to 2.5 hoursBut complex carbs are slowed down by their protein and fat contentSlide11
Carb Counting
Accounts for half the day’s controlAccuracy allows boluses to match carbs for post-meal control and a significantly lower A1c
Made easier with automatic carb bolus calculations by pumpAlways make an effort to estimate (if not count carbs)Slide12
D-teens count carbs POORLY
23%Slide13
TIP: A standing insulin dose (or regimen) is ALWAYS CHANGED LAST
When troubleshooting a type 1 diabetes blood sugar problem First consider…FoodTimingEquipmentBEFORE changing an insulin regimenSlide14
Why is the TDD so important?
TotalDaily
Dose(TDD)
1800/TDD = correction
500/TDD = carb ratio
TARGET BG
Insulin on Board (IOB)
(2-8 hours)
½ TDD/24 = basal rateSlide15
Average TDD insulin ranges by age and weight
0.6-0.8 U/kg/d (toddler)
0.8-1.0 U/kg/d
(child)
1.0-1.2 U/kg/d
(teen)Slide16
60 units
~ 30 units divided as boluses
30 units as glargine
60 units
1800 rule
30
60 units
500 rule
8.3 ~ 10
Insulin to carbohydrate ratio
TDD
Correction factor
(aka sensitivity factor)
Basal-Bolus: Example Calculations
Give dose at bedtime
10 – 10 – 10 +
snacks
OR…Slide17
Adjust The TDD For A High Avg. BG or A1C
Example: someone with a TDD of 35 units and few lows. A1c = 9%, so more insulin is needed: about 3.2 units.Slide18
worksheetSlide19
J.F.
7/6/01
8/7/89
8.0
49.7
7H
14N
5H
9 Lantus
35
35
35
26.2526
13
13
1.08
1.0
26
26
19
69.2
75
1:20
100-150
100-150
100-150
100-150
7/7/01
NovologSlide20
What is basal insulin?
Maintains balanceMinimizes drift/flux+/- 30 mg/dl over timeDoes not account for disruptive effect of snacks, activity or stressMay change over time Usually 40-60% of TDDSlide21
What defines an effective basal insulin?
(here’s a good visual)Slide22
Hints about basal insulin
50% Rule: basals usually make up 40 to 60% of an accurate Total Daily Dose
Basal rates will be similar through the day, such as between 0.45 and 0.7, or between 1.0 and 1.4
Adjust a basal rate in small steps – 0.05 to 0.1 u/hr
Change basals
3 to 8 hours
before need arisesSlide23
0.75 U/hr
Starting a basal rate
B A S A L
Example:
Pre-pump TDD = 48 units
75% of 48 units = 36 units
50% of 36 units = 18 units
18 divided into 24 hours = 0.75 U/hr
time
timeSlide24
0.75U/hr
Basal rates
0.5 U/hr
1.0 U/hr
Midnight
3 AM
6 AM
B A S A L
time
time
Programmed for the “typical” daySlide25
Survey: number of basal rates used
%
www.insulin-pumpers.org
N = 816Slide26
~2AM - 4AM is the physiologic nadir for insulin
~ 40% of hypoglycemia occurs during sleep! Often asymptomatic!
Breakfast
Lunch
Snack
Supper
Snack
bolus
bolus
bolus
2 - 4 AM
Breakfast
6 – 9 AM
SnackSlide27
Can’t “target practice” without a target!
Targets are specific numbers May vary based on time of day or other considerationsAre mathematical guides onlyMust be reasonably set Slide28
“Practice approaches perfect”Slide29
Selecting a blood sugar target
Upper and lower limits (range)A specific
numberIndividualized
Achievable
Adjustable
100 mg/dl
120 mg/dl
130 mg/dl
140 mg/dlSlide30
Set your BG
range
100-200
80-180
70-150
at least 75% of the time
reasonable
individualizedSlide31
Two week pumper log sheet
(complete the open spots)
Influenced by basal
Influenced by boluses
Checks overnight basal(s)Slide32
What defines a correction?
Correction: to bring something back into order or balanceDiabetes: to lower (or raise) and out of range blood sugar level.Situational variables
TimeQuantity
Recent/impending actions
Reproducibility?
Evolving nature?
Stock “correction”Slide33
5
time
0.75 U/hr
“Correction” dose
B A S A L I N S U L I N
.
.
.
.
.
.
.
.
.
.
.
.
2 hours
time
180 mg/dl
80 mg/dl
250 mg/dl
110 mg/dl
Example: 1 to 25
Actual – target / 25
250 – 125 / 25 = 5
5
“Acceptable” = “target” +/- 30 mg/dl
glucose
bolusSlide34
What defines a meal dose?
“Covers” the potential rise in sugar level after eating a meal.In non-D people, the 2 hour after meal BG is <140 mg/dl (by definition)Personal goals must be set by the patient/doc
Tight coverage by insulin for changes in blood sugar in non-diabetic peopleSlide35
Insulin to carb ratio
Based on the “500 Rule”
500 ÷ TDD = grams of carbs covered by 1 unit insulinExample: 500 ÷ 60 = 8.3 = ~ 8
Therefore: 1 unit for every 8 grams
Easier: 1 unit for 7.5 gm or 2 for 15 grams
15 grams = 1 carbohydrate choice
CHO
I
G
Blood sugar levelSlide36
6
time
0.75 U/hr
Insulin to Carb [I : CHO] ratio
B A S A L I N S U L I N
.
.
.
.
.
.
.
.
.
.
.
.
2 hours
time
180 mg/dl
80 mg/dl
125 mg/dl
150mg/dl
Example: 1 to 10
60 grams CHO / 10
60 / 10 = 6
6
“Acceptable” = “target” +/- 30 mg/dl
glucose
bolus
CHOSlide37
Carb Ratio or Factor
Carb factor – how many grams of carb are covered by 1 unit insulinCarb bolus is based on:Your carb factorHow many grams of carbs you
plan to eatYour BG allows a correction bolus determination
Amount of BOB (IOB) still active (ALSO determined from BG!)
A pump can determine the bolus needed for a meal when the carb count and the carb factor are accurate
Visit your dietitian to learn!Slide38
Check Your Carb Boluses
Does your carb factor work for LARGE meals? – half your weight (lbs) as grams of carbAre carb counts accurate?Are boluses given 20 min before meals when the glucose is normal?
For frequent lows after meals –> raise carb factor #
For frequent highs after meals –> lower carb factor #Slide39
An Accurate
Carb Ratio or Factor:Returns the blood sugar: to within 30 mg/dl (1.7 mmol
) of where it started by the time selected for your duration of insulin action (DIA)
with no lows within 5 hours after
carb
bolus givenSlide40
Carb
Bolus VarietiesNormal carb
bolusBolus taken immediately – most meals
Extended or square wave bolus
Bolus extended over time –
gastroparesis
, pizza
Combo or dual wave bolus
Some now, some later – bean burritos, al dente pastas and pizzas, SymlinSlide41
0.75 U/hr
Unused insulin
7 Units
6 Units
B A S A L
time
time
6 Units
4-6 hours
“Stacking effect”Slide42
Avoid Insulin Stacking
The goal is to help patients prevent over-correctingAvailable scientific data says how much active insulin remainsCurrent practices to avoid insulin “stacking” include:
Crude formulas (ie. 25% per hour or 50% of usual)Crude strategies
(ie. set a high Post-Prandial target BG)Slide43
Does blood sugar (yes or no)
Carbs to be eaten (limited by ability to count carbs effectively) (counts, guesses, or doesn’t count at all)
Insulin to carb ratio (uses or doesn’t use)
Insulin dose (given by doc, guessed, or calculated)
“Thinking like a
pancreas
” example
Correction or sensitivity factor, includes target blood sugar (yes or no)
220 mg/dl
1 to 50
75 gm
1 to15
T = 120
2 units
5 units
7 unitsSlide44
Bolus Size (Relative To Wt) Affects The DIA
Measured as units per kg(2.2 lb)Larger boluses have a longer duration of action.For 50 kg (110 lb) person: 0.3 u/kg = 15 u15 u/kg = 7.5 u
0.075 u/kg = 3.75 u
Becker et al. Diabetes. 2005; 54 (Suppl. 1): 1367P
4 hrs
How long a bolus will lower the BG:Slide45
Recommendations For DIA Times
DIAs on current pumps can be set from 2 to 8 hours. An inaccurate DIA can significantly impact control.
Mudaliar et al: Diabetes Care, 22: 1501, 1999Slide46
Basal/Bolus Balance
< 50% Basal
~ 50% Basal
> 50% Basal
Duration < 5 yrs
Thin
Physically active
High carb/low fat diet
Most people
Duration > 5 yrs
Puberty
Less active
Insulin resistant
Low
carb
dietSlide47
Stop Lows First
Better control and more stabilityMild lows cause followup lows Small epinephrine release makes muscles sensitive to insulinCan lead to another low as much as 36 hours after the firstMore carbs than usual are needed
Severe lows cause highs
Higher stress hormone release makes glucose rise for 6-10 hrs
Excess carb intake leads to highs
Boluses may be reduced/skipped
More insulin than usual needed
To stop lows, lower the TDD!!!Slide48
Benefits Of Frequent checking
Breakfast
100 (5.6)
200 (11)
400 (22)
300 (17)
Dinner
Lunch
Bed
1 test versus 7 tests a daySlide49
HbA1c=5.99+5.32 / (BGpd+1.39)
Atlanta Diabetes Associates study:
378 patients sorted from a database of 591
Pumps=MM 511 or earlier
BG Target=100
C peptide <0.1
Actual A1c Versus Testing Frequency
Data From 378 People On Pumps
ADA:
< 7%%
AACE:< 6.5%
P. Davidson et al: Diabetes 53 (suppl 2): abstract 430-P, 2004Slide50
Questions?