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Current And Emerging Technologies In Insulin Pumps & Continuous Monitors. May 8, 2008 John Walsh, PA, CDE jwalsh@diabetesnet.com (619) 497-0900 Advanced Metabolic Care + Research 700 West El Norte Pkwy Escondido, CA 92126 (760) 743-1431. Highlights. Background Smart Pumps and Features
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Current And Emerging Technologies In Insulin Pumps & Continuous Monitors May 8, 2008 John Walsh, PA, CDE jwalsh@diabetesnet.com (619) 497-0900 Advanced Metabolic Care + Research 700 West El Norte Pkwy Escondido, CA 92126 (760) 743-1431
Highlights • Background • Smart Pumps and Features • Pump Control Tips • DIA and BOB • Super Bolus • Continuous Monitors and Tips • Wrap Up
EDIC Study FindingsLower Glucose Prevents Heart Attacks & Early Death • After the DCCT ended in 1993, the EDIC Study has followed these participants. • Over 11 years, A1c levels in intensive and conventional control groups have been identical at 7.9% (was ~7.4% and ~9.1%). • However, heart attacks and strokes have been twice as high (98 vs 46) in the original conventional versus intensive group, even though A1c levels have been identical since the DCCT trial ended. 1. EDIC Study Group presentation at 2005 ADA, K.M. Venkat Narayan: Clinical Diabetes 24:88-89, 2006
EDIC Study FindingsLower Glucose Temporarily Reduces Nerve Damage • The tight control group also experienced half as much neuropathy • BUT, as shown in figure, improvedcontrol in the past delays progression but offers no long-term protection • Also, an A1c of 7.9% does not stopprogression of nerve damage (or CVD) Take Home: Improve control and KEEP it there! Avg A1c = 7.9% Diabetes Care, Vol 29, No. 2, pp. 340-344
Goal: A Healthy, Saner Life With Less Glucose Exposure And Variability The DCCT proved that exposure to high blood glucose was damaging. New emphasis is on glucose variability. Glucose Variability (Swing) = SD* from PC or meter Glucose Exposure = A1c or average BG from meter
Current Pump Reality Pumps provide only modest improvements in A1c levels over MDI: • About 0.6% lower (mid to upper 8% range) • Avg. A1c of 8.5% is well above goal of less than 7% or 6.5% But glucose levels ARE more stable with less insulin needed per day
Smart Pump Features – Overview • Automatic carb and correction calculations based on: • Carb and correction factors • Glucose targets • DIA avoids insulin stacking • Carb and correction boluses adjusted for BOB for accuracy and safety • Personal carb database • Correction bolus shown as % of TDD • Direct glucose entry and detailed glucose history • Reminders, alerts, weekly schedule, temp basal rates, etc.
Deltec Cozmo Features: # Pumps • HypoManager 1 • Weekly Schedule 1 • Missed Meal Bolus 1 • Bolus Not Completed 1 • Disconnect Bolus 1 • Basal Test 1 • Meal Maker with CozFoods 4 • Therapy Effectiveness 2 • BG Variability (SD) 1
Meter/CGM Improve BG History • Pump + Meter – direct BG entry • Deltec Cozmo + Freestyle CoZmonitor • Omnipod + Freestyle • Paradigm + Lifescan (US)/Bayer (Eur) • Pump + Cont Mon – no direct BG entry • Medtronic x22 + Paradigm RT • Future Pump + Meter/Monitor Combos • Animas pump + Lifescan meter • Cozmo + Abbott Navigator • Animas & Omnipod + Dexcom • AccuChek pump + meter
Disconnect Bolus • Disconnect up to 2 hrs forsports, sauna, sex, etc. • Useful for “Mini-vacations” • User estimates time off andpump gives up to 50% of missed basal as bolus • Alarm reminds user to re-connect • On reconnecting, pump shows missed basal and offers to supply the missing amount
Weekly Schedule • User’s profile changes automatically for specific days of the week • Allows different basal patterns and missed meal bolus alerts for each day of the week • No need to remember to change basal patterns or alerts • Great for college, shift work, weekends, exercise, or other regular variation in schedule
Pump or external controller contains user-selected food list for accurate carb counting for Easy carb calculations More accurate boluses Available in Animas 2020, Deltec Cozmo, Omnipod PDM, and Spirit PDA Pump As Carb Counter
Carb Bolus Varieties Regular • Taken immediately – for most meals Extended / square wave • Extended over time – gastroparesis Combo / dual wave • Some now, some later – bean burrito, some pastas and pizzas, Symlin
Helpful Aids And Alerts • Carb or insulin recommendation for each BG • Bolus-not-completed alert • Missed meal bolus alert • Check after high or low BG • 10 extra units for basal when reservoir reads zero • Easier analysis with TDD and basal/bolus balance • Overview of basal/bolus balance and correction bolus Not available in all pumps
Getting The Big PictureTherapy Effectiveness – A summaryof glucose and insulin history
Therapy Effectiveness Scorecard • Screen 1: • Average BG (over 2 to 30 days) • BG tests per day • BG standard deviation (SD) • Screen 2: • Carbs per day • TDD • % correction boluses • % carb boluses • % basal rates Largely available in Paradigm pumps as well
Therapy Scorecard Screen 1 Monitor control, testing frequency, glucose variability 14 Day Average: BG 146 mg/dl Tests 3.5/day Std Dev 53 mg/dl • Overall controlAdequacy of testingBG variability – aim forless than 65 mg/dl or less than half of average BG
Therapy Scorecard Screen 2 Monitors carb intake, TDD, basal/carb bolus balance, correction bolus% 14 Day Average: Carbs 206 g TDD 48.58 u Meal 38.07% Corr 4.95% Basal 56.98% • Boluses taken? Low carb diet?Guides therapy – A1c, lows, etcCarb bolus %Correction less than 8% of TDD?Basal at least 40 to 45% of TDD?
Check Correction Bolus % • If correction boluses make up more than 8% of the TDD (and lows are NOT a problem): • Move half of the excess units above 8% into basal rates or carb boluses • Raise the basal rates • Lower the carb factor • Or stop skipping carb boluses
Example: Correction Boluses Over 8% 10 Day Average: Carbs 175 g TDD 54.1 u Meal 36% Corr 21% Basal 43% Move 1/3 to 1/2 of the overage to basals or carb boluses: • 21% of 54.1 = 11.3 units, 8% of 54.1 = 4.3 units • 11.3 u - 4.3 u = 7 units excess • 1/3 to 1/2 of 7 u = 2.3 to 3.5 u to add to basals or carb boluses Over 8%
Therapy Effectiveness Guides TDD – Raise for frequent highs or high A1c Lower for frequent lows or for frequent lows and highs Basal/Bolus Balance – about 50% of TDD Correction Factor = ~ carb factor X 4.4 (mg/dl), carb factor / 4 (mmol) Correction Bolus % – if over 8% of TDD, move excess into basals or carb boluses Average BG – < 160 when checking before & after meals, < 140 when checking mainly before meals Standard Deviation – Keep less than 1/2 of avg BG or below 65 mg/dl
High BGs? Keep The Usual Suspects In Mind • I ate too much • Bad infusion set or site • Inaccurate carb counts • Missed or late boluses • Bad insulin • Stress hormone rebound • Empty refrigerator syndrome • Stress, pain, steroid meds
Bad Infusion Set Or Site If you have “unexplained” highs: • How often do they happen? • Do they correct only when you replace your infusion set? If you answer yes: • Always use tape to anchor the infusion line • Consider changing to a different infusion set The right infusion set and good site technique prevents headaches and improves your A1c
Tape The Tubing!!! Put 1” tape on the infusion line to stop Teflon tugs • Tape the tubing down to stop movement of Teflon catheter under the skin • Stops “unexplained highs” caused when insulin leaks back to surface • Less skin irritation • Prevents pull outs Lose tape not insulin! No anchor!
Tape The Tubing!!! Lose tape not insulin! Photo courtesy of kerri@sixuntilme.com
Use Sterile Technique For Site Prep 30% of people are constant staph carriers and 25% are intermittent. MRSA is now common. Prevent infections: • Wash hands • Sterilize skin with IV Prep • Place bio-occlusive IV3000 over site • Insert infusion set through IV 3000 • Steps for staph carriers: • Use antiseptic soap all over body once every 1-2 weeks • Occasionally, apply bacitracin ointment to inside of nose
Important Pump Settings • TDD – adjust when having frequent lows or highs • Basal % – basal/bolus balance, secure sleep • Basal rate variation – large variation not physiologic • Carb factor – postmeal control • Carb factor variation – may indicate basal problem • Correction factor – lower high BGs safely • DIA – bolus accuracy, HypoManager
CDA1 StudyCarb Factors From Cozmo CDA Study • Note how actual carb factors are distributed in blue • They are NOT bell-shaped!!! • People prefer “magic” numbers – 7, 10, 15, and 20 (grs/unit) – for their carb factors • A normal, bell-shaped, physiologic distribution is shown in green • MANY “magic” carb factors are inaccurate 10 7 115 20
Carb Factors From CDA1 Sudy • Graph shows carb factor versus TDD for 200 pumps with better control (avg BG < 209 mg/dl) • Note a break in relationship (red line) near a TDD of 40 u/day or carb factor of 10 • Suggests that people are hesitant to lower carb factors below 10
CDA1 Carb Rule #s Compared To PI The average carb factors in the blue boxes are those used in pumps with better control where the avg BG was 209 mg/dl or less. TDDs are shown in the tan box on the left. Carb Rule #s 450-475 475-625
CDA1 Basal/Bolus Balance • As TDD rises, basal percentage falls slightly from 51.7% at a TDD of 20 u to 49.4% at 40 u and 48.3% at 80 u • Basals vary widely – 27% to 83% of TDD • Many basal rates do not appear to be accurate • If correction bolus excess is distributed evenly into basals and carb boluses, “real” basal rates would average over 50% of TDD
Walsh-Roberts Rules For Optimum Readings • Starting TDD = (TDD X 0.9) + (wt [lbs]/4* X 0.9) ** 2 • Keep Basal/Bolus Balance near 50/50 • Basal test – rise/fall less than 30 mg/dl (1.7 mmol) over 8 hrs • 500 Rule for Carb Factor • 2000 Rule for Correction Factor (110 Rule for mmol) • Set DIA at 4 to 6 hrs • Keep correction boluses less than 8% of TDD * or kg/1.8 ** If current TDD less than wt/4 with good control, TDD = current TDD X 0.90 J Walsh and R Roberts: Pumping Insulin, 2006
Delay Eating When BG Is High Glucose exposure is reduced when high readings are allowed to fall before eating. Remember: Test early Don’t forget to eat on time Don’t forget you bolused
Duration Of Insulin Action (DIA)How long a bolus lowers your glucoseBolus On Board (BOB)Bolus insulin still active from previous boluses
ProblemMost Carbs Are Faster Than “Rapid” Insulin An hour later, half of most meal’s glucose rise has occurred, but 80% of rapid insulin activity remains Time over which most meals affect the BG % bolus activity remaining Take Home: Bolus 15 to 30 minutes before meals Use extended and combo boluses sparingly From Pumping Insulin
Food Digestion Time water 0 m fruit/veg juice 5-20 m fruit/veg salad 20-40 m melons/oranges 30 m apples/pears 40 m broccoli/caulif 45 m raw carots/beets 50 m potatoes/yams 60 m cornmeal/oats 90 m Typical Carb Digestion Times Food Digestion Time fish 30-60 m milk/cot cheese 90 m legumes/beans 120 m egg 45 m chicken 1.5-2 hr seeds/nuts 2.5-3 hr beef/lamb 3-4 hr cheese 4-5 hr Take Home: Choose combo foods to lengthen carb digestion time
Best Bolus Timing For Carbs Figure shows rapid insulin injected 0, 30, or 60 min before a meal Normal glucose and insulin profiles shown in the shaded areas DO NOT bolus an hour ahead of your meals!!!
Accurate DIA Prevents Lows Accurate DIA Time Accurate BOB Accurate Boluses Accurate HypoManager Prevents Lows
Short DIAs Hide Bolus Insulin Activity A short DIA hides true BOB level and its glucose-lowering activity • Causes “unexplained” lows • Leads to incorrect adjustments in basal rates, carb factors, and correction factors • Or user starts to ignore “smart” pump’s advice Set DIA based on real insulin action time. Do not modify DIA time to fix a control problem.
Duration Of Insulin Action (DIA) Accurate boluses require an accurate DIA DIA times shorter than 4 to 7 hrs will hide BOB and its glucose lowering activity Glucose-lowering Activity 0 6 hrs 2 hrs 4 hrs
Large Doses, Longer Duration • Large doses (0.3 u/kg or 30 u for 220 lb. person) of “rapid” insulin in 18 non-diabetic, obese people show significant activity beyond 4 hours. • Medium doses (0.2 u/kg or 10 u for 110 lb. person) show similar results. Large doses may lengthen DIA Apidra product handout, Rev. April 2004a
Dose Size May Affect Duration Of Action 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. 1993;42(Suppl. 1):54A
But Studies Routinely Underestimate DIA • To measure pharmacodynamics, glucose clamp studies are done in healthy individuals • SQ doses from 0.05 to 0.3 u/kg • But injected insulin ALSO SUPPRESSES normal basal release from the pancreas (grey area in figure) • Unmeasured basal suppression makes smaller boluses appear to have a shorter DIA • When basal suppression is accounted for, true DIA times become longer
Recommended DIA Times A DIA of 4 to 6 hrs gives best estimate for residual bolus activity A longer DIA is a safer DIA 4 hr Linear 4 hr Curvilinear From Pumping Insulin, 4th ed., adapted fom Mudaliar et al: Diabetes Care, 22: 1501, 1999
DIA Time Selection Current limited research suggests that DIA times are NOT different between children and adults Immediate factors can change insulin action time: • Shorter with activity and exercise • Shorter in hot weather • Longer with fat in diet Do not change DIA time for temporary factors
DIA Tips If pump often suggests boluses that are too small, do not shorten the DIA– it is rarely NOT problem Instead, ask what is causing the highs and where more insulin is needed – in basal rates, in carb boluses, or both DO NOT shorten the DIA for occasional activity. Instead: • lower boluses or basals ahead of time for planned activities • or eat more carbs or lower basals for unplanned activities Basal rates that are too low make the DIA appear SHORT!