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Insulin Pump Therapy
Bruce W. Bode, MD
and
Sandra Weber, MD
Goals of Targeted Insulin Therapy
(Intensive/Physiologic/Flexible)
•
•
•
•
Maintain near-normal glycemia
Avoid short-term crisis
Minimize long-term complications
Improve the quality of life
0
12
Hours
24
Physiological Serum Insulin
Secretion Profile
Plasma insulin (µU/ml)
75
Breakfast
Lunch
Dinner
50
25
4:00
8:00
12:00
16:00
Time
20:00
24:00
4:00
8:00
Basal/Bolus Treatment Program with
Rapid-acting and Long-acting Analogs
Plasma insulin
Breakfast
Lunch
Aspart
or
Lispro
Dinner
Aspart
or
Lispro
Aspart
or
Lispro
Glargine
4:00
8:00
12:00
16:00
Time
20:00
24:00
4:00
8:00
Variable Basal Rate:
CSII Program
Plasma insulin
Breakfast
Lunch
Dinner
Bolus Bolus
Bolus
Basal infusion
4:00
8:00
12:00
16:00
Time
20:00
24:00
4:00
8:00
Metabolic Advantages with CSII
• Improved glycemic control
• Better pharmacokinetic delivery of
insulin
— Less hypoglycemia
— Less insulin required
• Improved quality of life
Photograph reproduced with permission of manufacturer.
Pump Infusion Sets
Current Pump Therapy
Indications
•
•
Diagnosed with diabetes
(even new-onset type 1 diabetes)
Need to normalize blood glucose
— A1C > 6.5%
— Glycemic excursions
— Hypoglycemia
•
Need for flexible insulin program
CSII
Factors Affecting A1C
• Monitoring
— A1C = 8.3 - (0.21 x BG per day)
• Recording 7.4 vs 7.8
• Diet practiced
— CHO: 7.2
— Fixed: 7.5
— WAG: 8.0
• Insulin type (Aspart)
Bode et al. Diabetes 1999;48 Suppl 1:264
Bode et al. Diabetes Care 2002;25 439
Initial Adult Dosage: Calculations
Starting doses
• Based on pre-pump total daily dose (TDD)
 reduce TDD by 25% to 30% for pump TDD
• Calculated based on weight
 0.24 x weight in lb (0.53 x weight in kg)
Bode BW, et al. Diabetes. 1999;48(suppl 1):84.
Bell D, Ovalle F. Endocr Pract. 2000;6:357-360.
Crawford LM. Endocr Pract. 2000;6:239-243.
Target BG Ranges for CSII
• Normal
—Preprandial:
—1 hr postprandial:
70 - 140 mg/dl
<160 mg/dl
• Hypoglycemic unawareness
—Preprandial:
100 - 160 mg/dl
• Pregnant
—Preprandial:
—1 hr postprandial:
60 - 90 mg/dl
<120 mg/dl
Individually set for each patient
Fanelli CG et al., Diabetologia 1994, 37:1265-76.
Jovanovich L, AMJObGynec 1991, 164:103-11.
Initial Adult Dosage: Calculations
Basal rate
• 45% to 50% of pump TDD
• Divide total basal by 24 hours to
decide on hourly basal
• Start with only 1 basal rate
• See how it goes before adding basals
Basal Dose Adjustment Overnight
Rule of 30:
Check BG
 Bedtime
 12 AM
 3 AM
 6AM
Adjust overnight basal if readings
vary > 30 mg/dl
Basal Dose Adjustment Overnight
• Adults often need an increase in basal rate
in the “Dawn” hours (4 am to 9 am)
• Children often need an increase in basal
rate earlier starting at 10 pm to 2 am
Variable Basal Rate: CSII Program
Plasma insulin
Breakfast
Lunch
Dinner
Bolus Bolus
Bolus
Basal infusion
4:00
8:00
12:00
16:00
Time
20:00
24:00
4:00
8:00
Basal Dose Adjustment Daytime
Rule of 30:
Check BG
Before usual meal time
Skip meal
Every 2 hrs (for 6 hrs)
Adjust daytime basal if readings
vary > 30 mg/dl
Bolus Dose Calculations
Meal (food) Bolus Method 1
• Test BG before meal
• Give pre-determined insulin dose for
pre-determined CHO content
• Test BG after meal
• Goal < 60 mg/dl rise post meal or
< 160 mg/dl
Estimating the
Carbohydrate to Insulin Ratio (CIR)
Individually determined
• CIR = (2.8 x wgt in lbs) / TDD
• Anywhere from 5 to 25 g CHO is
covered by 1 unit of insulin
Davidson et al: Diabetes Tech & Therap. April 2003
Correction Bolus
• Must determine how much glucose is
lowered by 1 U of rapid-acting insulin
• This number is known as the
correction factor (CF)
• Use the 1700 rule to estimate the CF
• CF=1700 divided by TDD
example: if TDD=36 U, then
CF=1700/36=50, meaning
1 U will lower the BG 50 mg/dL
Correction Bolus Formula
Current BG - Ideal BG
Glucose Correction Factor
Example:
—Current BG:
—Ideal BG:
—Glucose CF:
220 - 100
50
220 mg/dL
100 mg/dL
50 mg/dL
= 2.4 U
If A1C is Not to Goal
Must look at:
• SMBG frequency
and recording
• Diet practiced
—Do they know what
they are eating?
—Do they bolus for all
food and snacks?
• Infusion site areas
—Are they in areas of
lipohypertrophy?
• Other factors:
—Fear of low BG
—Overtreatment of low
BG
Case Study # 1
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•
•
•
GL, male, age 39
Type 1 X 8 years
A1C= 7%; recent increase from 6%
CSII basal rates: 12 am 1.0 u/h;
4:30 am 1.6 u/h; 11:30 am 1.0 u/h
• Insulin: carbohydrate ratio =1u : 10 grams
• Correction Factor: BG - 100 divided by 40
• CGMS done to assist with improving
overall glycemic control
Modal Day View
Milk choc 15g; 8u
Cheese / Crackers
20 g; 3units
6u
Ice Cream; 3 u
2u; 57 g CHO
Juice box; no insulin
80 CHO; 7u
30 gm CHO;
Heavy Exercise
Most common bolusing errors
• Under-estimation of carbohydrates
consumed (CHO bolus)
• Over-correction of post-prandial
elevations (CF bolus)
— Remaining unused, active insulin
— Stacking of boluses
Bolus: Source of Errors
• “Inability” to count carbs correctly
— Lack of knowledge, skill
— Lack of time
— Too much work
• Incorrect use of SMBG number
• Incorrect math in calculation
• “WAG” estimations
The Major Problems
♦ Up until now we have not taken the
active insulin issue into
consideration
♦ The math involved with this has
become too complicated, and it
would be impossible to accurately
calculate the active insulin without
assistance
Smart Pumps
Bolus Wizard Calculator : meter-entered
Paradigm 512™
Paradigm Link™
• Monitor sends BG value to pump via radio
waves : No transcribing error
• Enter carbohydrate intake into pump
• “Bolus Wizard” calculates suggested dose
Insulin Activity Over Time
Insulin Activity (GIR)
700
Rapid Acting
Regular
600
500
400
300
200
100
0
0
1
2
3
4
5
6
Time (hrs)
Insulin Pharmacodynamic Data
Adapted from Henry R: Diabetes Care 1999
7
8
Adjusting for Active Insulin:
How smart pumps do it
Percent Remaining
100
Rapid Acting
Regular
80
60
40
20
0
0
1
2
3
4
Time (hrs)
5
6
7
8
Bolus Wizard Set Up Screen
Wizard:
On
Carb Units: grams
Carb Ratios: 10
BG Units:
mg/dl
Sensitivity:
50
BG Target:
100
For This System To Work
♦ It is critical the target, basal doses,
the correction doses, and the
carbohydrate ratios are accurate
♦ Understanding how to match
carbohydrate amounts with insulin
is critical
Do Smart Pumps Enable Others To
Go To CSII?
• YES
• All patients with diabetes not at goal
are candidates for Insulin Pump
Therapy
- Type 1 any age
- Type 2
- Diabetes in Pregnancy
Summary
• Insulin pump therapy offers improved
glucose control with less risk of
hypoglycemia and an improvement in
quality of life
• Appropriate candidate selection, training,
and follow-up ensures safe and effective
therapy
Questions
• For a copy or viewing of these
slides, contact
• WWW.adaendo.com