A Patient Safety Initiative For Insulin Pumps

1
A Patient Safety Initiative For Insulin Pumps
Manufacturing Standards to improve insulin pump
use and medical outcomes These proposals are
near final, although suggestions for editorial
changes are still welcome. Send your approval or
comments to John Walsh, PA, CDE at
jwalsh_at_diabetesnet.com or by calling (619)
497-0900
2
Introduction

• Over 500,000 insulin pumps are in use around the
  world, yet no formal guidelines regarding
  manufacturing standards and medical practice have
  been adopted by the diabetes clinical community
  and pump manufacturing industry.
• These are suggestions for such standards and once
  approved will be incorporated into future insulin
  pumps or into current pumps where software
  changes allow.
• These manufacturing standards are designed to
• Provide safer dosing increments to pump users
• Allow clinicians to make consistent dosing
  decisions when managing a variety of pumps
• Allow adjunctive medical and accessory personnel
  (ER, surgical, school nurses, etc.) to more
  easily be trained and interact with insulin pumps

3
Background

• Older insulin pumps were primarily designed to
  improve insulin delivery.
• Technological advances have transformed todays
  pumps and controllers into data collection
  centers. As additional data from continuous
  glucose monitoring devices becomes more widely
  used, the value of this data becomes even
  greater.
• Data needed for clinical monitoring and decisions
  is available in todays pump and can be accessed
  through screen displays, alerts, or
  recommendations. Using routine monitoring
  techniques and data analyses, a pump can inform
  the wearer regarding their current control and
  changes in control.

4
These Mechanical Standards Are Supported By

• John Walsh, PA, CDE
• Ruth Roberts, MA
• Gary Scheiner, MS, CDE
• Timothy Bailey, MD, FACE
• Steve Edelman, MD
• Carol Wysham, MD
• Joseph Largay, PA, CDE
• David Horwitz, MD
• Etc

Reservations by a signatory about a standard
will be noted
5
Definitions

• TDD total daily dose of insulin (all basals and
  boluses)
• Basal background insulin pumped slowly through
  the day to keep BG flat
• Bolus a quick surge of insulin as
• Carb boluses to cover carbs
• Correction boluses to lower high readings that
  arise from too little basal insulin delivery or
  insufficient carb boluses
• Bolus On Board (BOB) the units of bolus insulin
  with glucose-lowering activity still working from
  recent boluses
• Duration of Insulin Action (DIA) time that a
  bolus will lower the BG. This is used to
  calculate BOB.

6
Why Insulin Pump Guidelines Are Needed

• These mechanical standards are designed to
  improve
• Consistency of pump settings between pump
  manufacturers
• Accuracy and safety of carb and correction factor
  increments
• Safety and consistency of DIA defaults and
  increments
• Consistency in the handling of BOB and insulin
  stacking
• Improved monitoring for hypoglycemia
  hyperglycemia
• Improved entry of glucose values into bolus
  calculations
• Faster notification of excessive use of
  correction boluses
• Faster identification of control problems related
  to infusion sets

7
Overview
Slides are numbered by topic for easy reference.

• Topic
• Carb Factor Increments
• Correction Factor Increments
• Carb Factor Accuracy
• Correction Factor Accuracy
• DIA Default Times
• DIA Time Increments
• Handling Of BOB

Topic 8. Multi-Linear And Curvilinear DIA
9. Hypoglycemia Alert 10. Hyperglycemia
Alert 11. Correction Bolus Alert 12. Insulin
Stacking Alert 13. Automatic Entry Of BG
Values 14. Infusion Set Monitoring
8
ReviewWhat of The TDD Changes The BG?

• To understand some slides that follow, it helps
  to know the significance of the effect that a
  change in the TDD has on the glucose level.
• Using a 450 Rule to set the carb factor and a
  2000 Rule to set the correction factor
• 1.25 of an appropriate TDD for an individual is
  sufficient to change the glucose about 25 mg/dl
  when given as a single dose
• A 5 change in the TDD is equivalent to about a
  25 mg/dl increase or decrease in the glucose
  through the day
• A 5 to 6 change in the carb factor (about 2.5
  to 3 of the TDD) is sufficient to change the
  glucose about 20 mg/dl per meal.

9
Carb Factor Increments
1
10
1
Standard For Carb Factor Increments

• Carb factor increments shall be less than or
  equal to 5 of the next larger whole number so
  that each single step adjustment causes
  subsequent carb boluses to change by no more than
  5 from previous doses.
• We recommend minimum carb factor increments of 5
• 1.0 g/u above 20 g/u
• 0.5 g/u for 10 to 20 g/u
• 0.2 g/u for 5 to 9.8 g/u
• 0.1 g/u for 3 to 4.9 g/u
• 0.05 g/u for 0.1 to 2.95 g/u

5 Improved carb factor increments recommended by
Gary Scheiner, MS, CDE
11
Carb Factor (CarbF) Increments
1

• Issue Current carb factor increments are too
  large to provide accurate carb boluses,
  especially for those who use smaller carb
  factors. This can represent a safety issue in
  situations where current carb factors lack the
  precision required to avoid excessive
  hyperglycemia and hypoglycemia.

12
ExampleCarb Factor Increments
1

• Most pumps offer 1 gram per unit as their
  smallest CarbF increment. This increment becomes
  relatively large for CarbFs below 15 or 20 g/u.
• For instance, when the carb factor is reduced
  from 10 to 9 g/u, all subsequent carb boluses are
  increased by 11.1. A shift in the carb factor
  from 1u/5g to 1u/4g causes each subsequent carb
  bolus to increase by 25.
• For most pump users, a change in the carb factor
  larger than 5 or 6 would be expected to create
  more than a 20 mg/dl shift in the glucose
  following each meal.

13
ExampleImpact On BG From CarbF Adjustments
1

• This table shows the average additional fall in
  glucose after each meal of the day when a carb
  factor is reduced from 10 grams per unit to 9
  grams per unit (for appropriate weight TDD),
  and from 5 gr per unit to 4 gr per unit.

Meals with higher carb intake would magnify
these sample glucose changes
Calculated as avg. carbs/day avg.
carbs/day X 1 X 2000
new carb factor old carb factor 3 TDD
14
ReviewMedian Carb Factor
1

• In unpublished data from the Cozmo Data Analysis
  Study
• The median (middle) carb factor was 11.2 g/u
• Almost all pumpers used carb factors below 20 g/u
• 40 or more use carb factors of 10 g/u.

15
What Current Changes In CarbFs Do
1

• Table shows how subsequent carb boluses are
  affected by a one-step reduction in the CarbF
  using different CarbF increments. Yellow area
  shows values for most current pumps. Green areas
  show safer increments that impact subsequent
  boluses less than 5.

16
Correction Factor Increments
2
17
2
Standard For Correction Factor Increments

• For similar reasons, correction factor increments
  shall be less than or equal to 5 of the next
  larger whole number so that each single step
  adjustment causes subsequent correction boluses
  to change by no more than 5 from previous doses.
  
• We recommend minimum correction factor increments
  of
• 5.0 mg/dl per u above 80 mg/dl per u
• 2.0 mg/dl per u for 40 to 78 mg/dl per u
• 1.0 mg/dl per u for 20 to 39 mg/dl per u
• 0.5 mg/dl per u for 10 to 19.5 mg/dl per u
• 0.2 mg/dl per u for 5 to 9.8 mg/dl per u
• 0.1 mg/dl per u for 3 to 4.9 mg/dl per u
• 0.05 mg/dl per u for 0.1 to 2.95 mg/dl per u

18
Carb Factor Accuracy
3
19
3
Standard For Verification Of Carb Factor Accuracy

• Insulin pump companies shall record and publish
  each year the carb factors used in insulin pumps
  returned for upgrade or repair. This report will
  include sufficient numbers of pumps to ensure
  statistical significance for commonly used carb
  factors between 5 and 20 grams per unit to ensure
  that pump training and clinical followup are
  assisting in the selection of accurate carb
  factors.
• To improve accurate selection of carb factors,
  efforts shall be undertaken to automate carb
  factor testing.

20
Personal Carb Factors
3

• Issue Many carb factors used in insulin pumps
  today are poorly tuned to the users need.
• When a carb factor does not match an individuals
  need, other sources of error in carb bolus
  calculations are significantly magnified.

21
Review Carb Factors In Use 1
3

• Avg. carb factors for 468 consecutive Cozmo
  insulin pump downloads (gt126,000 boluses) are
  shown in blue
• Note that they are NOT bell-shaped or physiologic
• People prefer magic numbers 7, 10, 15, and 20
  g/unit for their carb factors
• Determined directly from grams of carb divided
  by carb bolus units for each carb bolus

10
7
115
20
1
22
ReviewCarb Factors In Use 1
3

• MANY magic carb factors, shown in blue, are
  inaccurate. A more normal or physiologic
  distribution is shown in green
• Use of magic numbers creates major, consistent
  bolus errors that magnify other sources for error

10
7
115
20
1
23
Correction Factor Accuracy
4
24
4
Standard For Verification Of Corr Factor Accuracy

• Insulin pump companies shall record and publish
  each year the correction factors used in insulin
  pumps returned for upgrade or repair. This report
  will include sufficient numbers of pumps to
  ensure statistical significance for commonly used
  correction factors between 20 and 80 mg/dl per
  unit to ensure that pump training and clinical
  followup are assisting in the selection of
  accurate correction factors.
• To improve accurate selection of correction
  factors, efforts shall be undertaken to automate
  correction factor testing.

25
Personal Correction Factors
4

• Issue Many correction factors used in insulin
  pumps today are poorly tuned to the users need.
  This inaccuracy significantly magnifies other
  sources of error in correction bolus
  calculations.

26
Review Correction Factors In Use 1
4

• Avg. correction factors in use for 452
  consecutive Cozmo insulin pump downloads
• Like carb factors, correction factors in use are
  NOT bell-shaped or physiologic. A more accurate
  choice of correction factors would create a
  bell-shaped curve.
• Users or clinicians appear to frequently select
  magic numbers for correction factors.

10
7
115
20
1
27
DIA Default Times
5
28
Standard ForDIA Default Times
5

• Default duration of insulin action (DIA) times in
  current pumps vary widely between 3 and 6 hours.
  For safety in bolus calculations that depend on
  DIA, the DIA default shall be set no shorter than
  4.5 hours in pumps that determine DIA in a linear
  fashion and no shorter than 5 hours in pumps that
  determine DIA in a curvilinear or multi-linear
  fashion. These default times apply for the rapid
  insulins (lispro, aspart, and glulisine) in use
  at this time.

29
DIA Default Time Settings
5

• Issue DIA measures the glucose-lowering activity
  of a carb or correction bolus over time. Current
  default times for DIA range from 3 to 6 hours in
  different pumps.
• The DIA is often considered another tool to
  improve control rather than being set at an
  appropriate value and focusing on more
  appropriate changes in basal rates or carb and
  correction factors to improve control.
• A DIA that is too short allows excess
  unrecognized bolus insulin to accumulate, usually
  in the afternoon and evening hours.
• Example a bolus given at 7 am appears to have no
  activity after 10 am. If a high BG occurs 10 am,
  more bolus than needed will be given. At lunch,
  the bolus will be excessive, regardless of the BG
  at that time, creating a high likelihood of
  hypoglycemia.

30
ReviewHow Long Do Boluses Lower The BG?
5

• Numerous GIR studies show rapid insulins lower
  the glucose for 5 hours or more.
• With Novolog (aspart) at 0.2 u/kg (0.091 u/lb),
  23 of glucose lowering activity remained after 4
  hours.12
• Another study found Novolog (0.2 u/kg) lowered
  the glucose for 5 hours and 43 min. /- 1 hour.13
• After 0.3 u/kg or 0.136 u/lb of Humalog (lispro),
  peak glucose-lowering activity was seen at 2.4
  hours and 30 of activity remained after 4 hours.
  11
• These times would be longer if the unmeasured
  basal suppression in pharmacodynamic studies were
  accounted for.

11 From Table 1 in Humalog Mix50/50 product
information, PA 6872AMP, Eli Lilly and Company,
issued January 15, 2007. 12 Mudaliar S, et al
Insulin aspart (B28 Asp-insulin) a fast-acting
analog of human insulin. Diabetes Care 1999
221501-1506. 13 L Heinemann, et al Time-action
profile of the insulin analogue B28Asp. Diabetic
Med 199613683-684.
31
ReviewShort DIAs Hide Bolus Insulin Activity
5

• A short DIA time hides true BOB level and its
  glucose-lowering activity. This can be a safety
  issue in that it
• Leads to unexplained lows
• Leads to incorrect adjustments in basal rates,
  carb factors, and correction factors
• Causes users to start ignoring their smart
  pumps advice
• An inappropriately long DIA time overestimates
  bolus insulin activity this leads to
  underdosing rather than overdosing on subsequent
  boluses.
• DIA should be based on an insulins real action
  time.
• Do NOT modify the DIA time to fix a control
  problem

32
ReviewDuration Of Insulin Action (DIA)
5
Accurate bolus estimates require an accurate DIA.
DIA times shorter than 4.5 to 7 hrs may hide BOB
and its glucose lowering activity
Glucose-lowering Activity
6 hrs
2 hrs
0
4 hrs
33
ReviewDIA
5

• Large doses (0.3 u/kg 30 u for 220 lb. person)
  of rapid insulin in 18 non-diabetic, obese
  people
• Med. doses (0.2 u/kg 20 u for 220 lb. person)
• This study suggests that residual insulin
  activity can lower glucose levels for 7-8 hours

Regular
Apidra product handout, Rev. April 2004a
34
ReviewDoes Dose Size Affect DIA?
5

• This graphic suggests that smaller boluses do not
  lower the BG as long as larger boluses.
• However, this may not be true see next 2
  slides.
• Size of the injected Humalog dose for a 154 lb or
  70 kg person
• 0.05 u/kg 3.5 u
• 0.1 u/kg 7 u
• 0.2 u/kg 14 u
• 0.3 u/kg 21 u

Woodworth et al. Diabetes. 199342(Suppl. 1)54A
35
ReviewPharmacodynamics Is Not DIA
5

• The DIA time entered into an insulin pump is
  based on studies of insulin pharmacodynamics.
• However, the traditional method used to determine
  the pharmacodynamics of insulin may underestimate
  insulins true duration of action, as shown in
  the next two slides.

36
ReviewPharmacodynamics Underestimates DIA And
Overestimates Impact Of Bolus Size
5

• To measure pharmaco-dynamics, glucose clamp
  studies are done in healthy individuals (0.05 to
  0.3 u/kg)
• Because there is no basal suppression, this
  injected insulin ALSO SUPPRESSES normal basal
  release from the pancreas (grey area in figure)

37
ReviewPharmacodynamic Time Does Not Equal DIA
5

• After accounting for the lack of basal
  suppression,
• True DIA times become longer than the PD times
  derived in traditional research
• If basal suppression activity is accounted for,
  small boluses may be found to have a longer DIA
  than it currently appears, erasingsome of the
  apparent variation in DIA related to bolus size
• Some of the apparent inter-individual variation
  in pharmacodynamics may also disappear

38
DIA Time Increments
6
39
6
Standard For DIA Time Increments

• For safe and accurate estimates of residual BOB,
  DIA time increments shall be no greater than 15
  minutes.

40
DIA Time Increments
6

• Issue Current DIA time increments vary from 15
  minutes to 1 hour in different pumps
• When a pumps DIA time is adjusted, large time
  increments, such as 1 hr, can introduce large
  changes in subsequent estimates of BOB.
• For example, when the DIA is reduced from 5 hours
  to 4 hours, subsequent BOB estimates are
  decreased and recommendations for carb boluses
  are increased by about 25.

41
ReviewGlucose Infusion Rate (GIR) Studies
6

• Most GIR studies suggest that pharmacodynamic
  action of insulin varies only about 25 to 40
  between individuals.
• For a DIA time of 5 hr and 15 min, a 25 range is
  equivalent to 1 hr and 20 min, such as from 4 hrs
  and 30 min to 5hr and 50 min.
• A pump that has 1 hr DIA increments would enable
  the user to select only 1 or 2 settings within
  this physiologic range, while a 30 min increment
  would allow only 2 or 3 choices that are close to
  a physiologic range.

42
Handling Of BOB
7

• Bolus On Board (BOB)

43
Standard ForHandling Of BOB
7

• For safe and accurate BOB measurement
• BOB measurements shall include all carb and
  correction boluses given within the selected DIA
• When residual BOB is present at the time of a
  bolus, the BOB shall be subtracted from both carb
  and correction bolus recommendations.
• When BOB exceeds the current correction bolus
  need or the current carb plus correction need,
  the user will be alerted to how many grams of
  carb they need to eat.(BOB correction carb
  bolus need) X carb factor

44
Handling Of BOB
7

• Issue Current pumps differ significantly in what
  is counted as BOB and in whether or not BOB is
  subtracted from subsequent carb boluses.
• Most insulin pumps assume that excess BOB does
  not need to be taken into account when
  determining the next carb bolus.
• Though commonly determined in this way, the
  resulting bolus dose recommendations can cause
  unexplained and unnecessary insulin stacking and
  hypoglycemia.

45
ExampleInsulin Stacking
7

• With a bedtime BG of 173 mg/dl,
• is there an insulin deficit or a carb deficit?

Bedtime BG 173 mg/dl
Correction
Dessert
Dinner
6 pm
8 pm
10 pm
12 am
46
ReviewFrequency Of Insulin Stacking
7

• CDA1 Study Results
• Of 201,538 boluses, 64.8 were given within 4.5
  hrs of a previous bolus
• Although 4.5 hours may underestimate true DIA,
  use of this minimal DIA time shows that some BOB
  is present for MOST boluses

4.5 hrs
47
ReviewBolus On Board (BOB)
7

• An accurate measurement of the glucose-lowering
  activity that remains from recent boluses
• Prevents insulin stacking
• Improves bolus accuracy
• Allows the current carb or insulin deficit to be
  determined

aka insulin on board, active insulin, unused
insulin Introduced as Unused Insulin in 1st ed
of Pumping Insulin (1989)
48
ReviewHow Current Pumps Handle BOB
7
Except when BG is below target BG
Yes is generally safer
49
ExampleUnsafe BOB1 Handling
7

• If a pump user gets frustrated with a high BG and
  they overdose to speed its fall, or they exercise
  longer or more intensely than anticipated, they
  can acquire a significant excess in BOB.
• In this situation, most current pumps recommend
  that a bolus be given for all carb intake
  regardless of how much BOB is actually present.
• If BOB is greater than the correction bolus
  requirement at the time, the pumps bolus
  recommendation may introduce a risk for
  hypoglycemia.

1 Pumping Insulin, 1st ed, 1989, Chap 12, pgs
70-73 The Unused Insulin Rule
50
ExampleDifferences In Bolus Recommendations
7

• Situation BOB 3.0 u and 30 gr. of
  carb will be eaten at these glucose levels
• Carb factor 1u / 10 gr
• Corr. Factor 1 u / 40 mg/dl over
  100
• Target BG 100
• TDD 50 u

The graphic shows how widely bolus
recommendations vary from one pump to another for
the same situation.
units
mg/dl
Omnipod bolus cannot be determined - it counts
only correction bolus insulin as BOB
51
ReviewTrack BOB Or Carb Digestion?
7

• For safety after meal and correction boluses,
  tracking the glucose-lowering action of BOB is
  more important than accounting for the
  glucose-raising action of digesting meal carbs
• When a BG is taken after a meal, the BOB times
  the correction factor ideally represents the
  maximum fall in glucose expected.
• Accounting for the impact of the BOB on the
  current glucose provides the safest approach in
  the determination of bolus recommendations.
• Low glycemic index meals, gastroparesis, Symlin,
  and other issues may counteract a predicted fall
  in glucose based on BOB, but the user can more
  easily judge and remedy this situation than
  dealing with an unknown excess of insulin.

52
Exceptions To Usual Handling Of BOB
7

• When a second bolus is taken for an unplanned
  carb intake or a desert that is consumed within
  60 minutes or so of a meal bolus, BOB should not
  be taken into account for the second bolus
  because the impact of the first bolus cannot be
  accurately determined.
• Given that, it is wise to account for BOB as soon
  after a meal as possible, such as within 60 to 90
  minutes, to provide early warning if the bolus
  given was excessive or inadequate.

Accounting for all BOB and applying it to
subsequent boluses is generally safer, although
not always more accurate.
Adjustable setting in pump/controller
53
Multi-Linear And Curvilinear DIA
8
54
Standard ForMulti-Linear And Curvilinear DIA
8

• Insulin pumps shall use either a 100 curvilinear
  or a multi-linear method to improve accuracy and
  consistency of BOB estimates.

55
Linear And Curvilinear DIA
8

• Issue Pump manufacturers use at least 3
  different methods (100 curvilinear, 95 of
  curvilinear, and straight linear) to measure DIA
  and BOB.
• When a realistic DIA time is selected, a linear
  determination of residual BOB will not be as
  accurate as a curvilinear method that
  incorporates the slow onset of insulin action and
  its longer tailing off in activity. In most
  situations, an accurate determination of
  insulins tailing activity will be most important
  to the pump user.

56
Linear And Curvilinear DIA Compared
8

• Note how values for the 5 hr linear line in red
  and the thinner 5 hr curvilinear line diverge in
  value at several points along the graph.

5 hr Linear
5 hr 95 Curvilinear
From Pumping Insulin, 4th ed., adapted fom
Mudaliar et al Diabetes Care, 22 1501, 1999
57
ExampleA Multi-Linear DIA
8

• Use of a multi-linear method to measure DIA
  improves accuracy. The next page shows a
  triple-linear example for measurement of BOB.

58
ExampleA Triple-Linear Approximation Of DIA
8

• A triple-linear line in red can more closely
  approximate a curvilinear DIA.
• For a 5 hr DIA
• 1st 10 no change
• Mid 65 fall 75
• Last 25 fall 25 ( adjustable as needed
  in device)

5 hr Triple Linear
modification suggested by Gary Scheiner, MS,
CDE
59
Hypoglycemia Alert
9
60
Standards ForHypoglycemia Alert
9

• Insulin pumps that store glucose and insulin
  dosing data shall present this glucose control
  data in a readily accessible form on the pump or
  controller.
• The pump shall alert the user when the glucose
  data from their glucose monitor or continuous
  monitor suggests they are experiencing frequent
  or severe patterns of hypoglycemia.

Adjustable settings in pump/controller
61
Frequent/Severe Hypoglycemia Alert
9

• Issue Although most current insulin pumps
  contain sufficient data to do so, pumps give no
  warning to a user when they are experiencing
  patterns of frequent or severe hypoglycemia.

62
ExamplePump Screen Hypoglycemia Display 1
9
Modified to display per Gary Scheiner, MS, CDE
Adjustable settings in pump/controller
63
ExamplePump Screen Hypoglycemia Display 2
9
Modified to display per Gary Scheiner, MS, CDE
Adjustable settings in pump/controller
64
Hyperglycemia Alert
10
65
Standards ForHyperglycemia Alert
10

• Insulin pumps that store glucose and insulin
  dosing data shall present this glucose control
  data in a readily accessible form on the pump or
  controller.
• The pump shall alert the user when the glucose
  data from their glucose monitor or continuous
  monitor suggests they are experiencing patterns
  of frequent or severe hyperglycemia.

Adjustable settings in pump/controller
66
Frequent/Severe Hyperglycemia
10

• Issue Although most current insulin pumps
  contain sufficient data to do so, pumps give no
  warning to a user when they are experiencing
  patterns of frequent or severe hyperglycemia.

67
ExamplePump Screen Hyperglycemia Display 1
10
Modified to display per Gary Scheiner, MS, CDE
Adjustable settings in pump/controller
68
ExamplePump Screen Hypoglycemia Display 2
10
Modified to display per Gary Scheiner, MS, CDE
Adjustable settings in pump/controller
69
Correction Bolus Alert
11
70
Standard ForCorrection Bolus Alert
11

• Insulin pumps shall show in a readily accessible
  history screen the percentage of the TDD that is
  used for correction boluses over time.
• The insulin pump shall alert the wearer when they
  are using more than 8 of their TDD for
  correction bolus doses in the most recent 4 day
  period.

Adjustable settings in pump/controller
71
Correction Bolus Alert
11

• Issue Hyperglycemia is more common than
  hypoglycemia for most people on insulin pumps.
• When glucose levels consistently run high, many
  pump users address the problem by giving frequent
  correction boluses rather than correcting the
  core problem through an increase in their basal
  rates or carb boluses.
• If the correction bolus becomes excessive
  relative to the TDD, this information is often
  not shown and no alert is given regarding the
  possible excessive use of correction boluses.

72
Insulin Stacking Alert
12

• Accurate accounting of BOB becomes more important
  in those who experience frequent or severe
  hypoglycemia, as well as those whose average
  glucose levels are closer to normal values.

73
Standard ForInsulin Stacking Alert
12

• Insulin pumps shall alert the wearer when they
  are giving a bolus and no glucose value has been
  entered in the pump. This is especially necessary
  when the user has sufficient insulin stacking to
  significantly alter the bolus they would
  otherwise give.
• The alert is on by default once a DIA time is
  selected to measure BOB, but may be turned off if
  the user desires.

Such as when the BOB is greater than 1.25 of
the avg. TDD, sufficient to change the glucose
about 25 mg/dl. ( Adjustable setting in
pump/controller for a certain fall in glucose
selected by the user or clinician)
74
Insulin Stacking Alert
12

• Issue Pump users often bolus for carbs without
  checking their glucose first. With no glucose
  reading, the pump cannot account for BOB, nor
  appropriately adjust a bolus for the BOB or the
  current BG.
• Even without a glucose test, data available in
  the pump at the time of a bolus can determine
  whether enough BOB is present to substantially
  change a bolus dose. The pump can alert the user
  to this unseen, substantial insulin stacking.

75
ExampleInsulin Stacking or BOB Alert
12

• When a carb bolus is planned without a recent BG
  check, but BOB is more than 1.25 of the average
  TDD (enough to cause about a 25 mg/dl drop in the
  glucose), the pump will recommend that the wearer
  do a BG check due to the substantial presence of
  BOB.
• For instance, for someone with
• Avg TDD 1.25 of TDD
• 40 units 0.5 units
• 50 mg/dl per u (corr factor) X 0.5 u 25
  mg/dl
• This individual would be alerted when they do not
  check their glucose and want to give a bolus but
  have 0.5 u or more of BOB present.

Adjustable in pump/controller for a reasonable
degree of safety
76
Automatic Entry Of BG Values
13
77
Standard ForAutomatic Entry Of BG Values
13

• For completion of the glucose history, improved
  handling of BOB, and more accurate bolus
  recommendations, insulin pumps shall be enabled
  to have wireless or direct entry of BG test
  results from a glucose meter.
• Automatic glucose entry from two or more major
  brands of meters is recommended to increase the
  likelihood of insurance coverage for test strips.

78
Automatic Entry Of BG Values
13

• Issue Pump users do not enter as many BG values
  into their pump when readings must be entered
  manually rather than having a glucose value
  automatically entered from a meter.
• When a glucose is checked but not entered, the
  lost data cannot be used to account for BOB, warn
  of insulin stacking (see 12), nor be used to
  analyze glucose patterns and the frequency of
  hypoglycemia and hyperglycemia.
• Relatively normal and hypoglycemia values are
  less likely to be entered manually, but are more
  likely to be influenced by BOB.

79
ReviewAutomatic Entry Of BG Values
13

• In a study of over 500 insulin pumps where BG
  values could be entered either manually or
  automatically, users entered 2.6 BG values per
  day manually, compared to 4.1 values per day for
  pumps in which glucose values wre automatically
  entered.
• BOB could typically be taken into account for 1.5
  additional boluses per day with automatic entry
  of BG values.
• When glucose values are not automatically
  entered, BOB cannot be determined and bolus
  recommendations will not be as accurate.

J. Walsh, D. Wroblewski, T.S. Bailey
unpublished data
80
ReviewAutomatic Entry Of BG Values
13

• Automatic entry of glucose values into pumps
  offers a significant clinical advantage to users
  because more boluses will be adjusted for high
  and low BGs, and residual BOB is more likely to
  taken into accout in bolus calculations.
• Automatic entry of glucose values ensures a
  greater degree of safety for those who experience
  frequent or sever hypoglycemia, and those whose
  glucose values are closer to normal.

81
Infusion Set Monitoring
14
82
Standards ForInfusion Sets
14

• Insulin pumps shall monitor and record in easily
  accessible history the duration of infusion set
  usage recorded as mean, median, and SD of time of
  use.
• Insulin pumps shall monitor and report average
  glucose values in full and partial 24 hour time
  intervals between set changes with the ability to
  change the observation interval, such as 1 to 30
  set changes.
• These steps allow the HCP and user to identify
  infusion set problem from loss of glucose control
  and variations in patterns of use.

Adjustable setting in pump/controller
83
Infusion Sets
14

• Issue A significant number of non-patch pump
  wearers encounter infusion set problems. These
  problems may arise from poor infusion set design
  or inadequate site preparation. Often the source
  for the randomly erratic glucose readings that
  follow are difficult to identify by a user or
  clinician.

84
ReviewInfusion Set Failure
14

• One common problem source for infusion set
  failure arises when a Teflon infusion set comes
  loose beneath the skin from movement or tugging.
  Some of the infused insulin then leaks back to
  the skin surface resulting in unexplained high
  readings.
• A complete loss of glucose control is typically
  seen when an infusion set is pulled out entirely.
  
• Selecting the right infusion set plus good site
  technique, especially taping the infusion line to
  the skin, can significantly minimize the number
  of unexplained high readings for many pump
  wearers.

85
Why The Tubing Needs To Be Taped
14

• Most problems with infusion sets come from
  loosening of the Teflon under the skin, not from
  a complete pullout. A 1 tape placed on the
  infusion line
• Stops tugging on the Teflon catheter under the
  skin
• Prevents loosening of the Teflon catheter under
  the skin
• Avoids many unexplained highs caused when
  insulin leaks back to the skin surface
• Reduces skin irritation
• And prevents many pull outs

86
Tape The Tubing
14

• This helps prevent
• Tugging
• Irritation
• Bleeding

87
ExamplesLack Of Anchoring Of Sets
14
A review of dozens of pictures of infusion sets
online and pump manuals finds that anchoring of
the infusion line with tape is rarely recommended
or practiced.
No tape!
88
Review Infusion Set Monitor
14

• Many pump wearers experience random erratic
  readings until they change to a different
  infusion set or start to anchor their infusion
  lines with tape to stop line tugging.
• However, insulin pumps offer no mechanism for
  clinicians or pump users to detect who may be
  having problems with their infusion sets.

89
ToolInfusion Set Monitor
14

• Insulin pumps with direct BG entry can identify
  those who may be having intermittent loss of
  glucose control secondary to infusion set
  failure. The pump
• Shows the average time and variation in time of
  use between reservoir loads or use of the priming
  function.
• Shows average BGs for each full or partial 24
  hour time interval following set changes
  (indicated by the prime function) over a various
  number of set changes or as soon as statistical
  significance is reached.

Adjustable setting in pump/controller