GLUCOSE SENSING

Making the Most of Continuous Glucose Monitoring

Gary Scheiner MS, CDEOwner & Clinical DirectorIntegrated Diabetes Services LLCWynnewood, PAAADE 2014 Diabetes Educator of the Yeargary@integrateddiabetes.com(877) 735-36481CGM OptionsFDA ApprovedMedtronic 530G integrated pump w/Enlite sensorMedtronic Guardian REAL-Time SystemDexCom G4 Platinum/ShareMedtronic iPro, Dexcom G4 ProfessionalPending FDA ApprovalFreestyle LibreMedtronic 640G Dexcom G5How They WorkGlucose sensor is inserted in subcutaneous tissue and connected to a transmitterSCSensorTransmitterPump or Handheld MonitorGlucose sensor sends values to the transmitterTransmitter then sends data wirelessly to a pump or handheld monitor every 5 minutes, where data can be viewed and acted upon in real-timeInterstitial Fluid and Lag Time

(V2)Plasma(V1)Capillary glucose must diffuse into the interstitial fluid (ISF)ISF glucose levels may lag capillary levels by 515 minutesWhen glucose levels are stable, ISF glucose levels and capillary blood glucose levels are similarOverall, the sensor glucose trends are more important than the absolute measurementsIllustration adapted from Rebrin K, et al. Am J Physiol. 1992;277:E561E571.What Do We Get in Real Time?NumbersAlertsTrends

The Numbers:Ballpark Estimates +/- 20% if >80 (4.4)+/- 20 mg/dl if 3 mg/dl/min) (.17)

Decision-Making Based on Trend InformationSelf-Care ChoicesTo snack?To check again soon?To exercise?To adjust insulin?Key SituationsDrivingSportsTestsBedtime

15Third, REAL-Time Trend Arrows.

One arrow up or down indicates a change of 1-2 mg/dl/min in the last 20 minutes.Two arrows up or down indicate a change of more than 2 mg/dl/min in the last 20 minutes.Arrows are only displayed if there has been at least a 1 mg/dl/min change in the last 20 minutes.

Patients should think about where glucose may be in 20 minutes if it continues at the same rate.

Bolus AdjustmentBased on Trend InformationBG Stable: Usual Bolus DoseBG Rising Gradually: bolus slightly*BG Rising Sharply: bolus modestly**BG Dropping Gradually: bolus slightly*BG Dropping Sharply: bolus modestly*** Enough to offset 25 mg/dl (1.5 mmol/l) ** Enough to offset 50 mg/dl (3 mmol/l)16Third, REAL-Time Trend Arrows.

One arrow up or down indicates a change of 1-2 mg/dl/min in the last 20 minutes.Two arrows up or down indicate a change of more than 2 mg/dl/min in the last 20 minutes.Arrows are only displayed if there has been at least a 1 mg/dl/min change in the last 20 minutes.

Patients should think about where glucose may be in 20 minutes if it continues at the same rate.

Hypo Treatment Based on Trend InformationPredictive Hypo Alert or Hypo Alert & recovering: Subtle Treatment 50% of usual carbsMed-High G.I. food Hypo Alert & Dropping: Aggressive TreatmentFull or increased carbsHigh G.I. food

vs17Third, REAL-Time Trend Arrows.

One arrow up or down indicates a change of 1-2 mg/dl/min in the last 20 minutes.Two arrows up or down indicate a change of more than 2 mg/dl/min in the last 20 minutes.Arrows are only displayed if there has been at least a 1 mg/dl/min change in the last 20 minutes.

Patients should think about where glucose may be in 20 minutes if it continues at the same rate.

What Can We Get From Analyzing CGM Data?(a retrospective journey)Completely Overwhelmed!

19In clinics that have utilized the MiniMed Paradigm REAL-Time System in studies, certain experiences can be gained. An analysis of patients who did well experienced benefits from using it continuously or at least 90 percent of the time. Patients who have experience with insulin pump therapy seemed to benefit more than those who were new to pump therapy and therefore still learning how to optimize their insulin pump usage. Patients who looked at it frequently, almost 10-20 times per day, but did not overreact to the data. Patients who had their CareLink data examined by the healthcare team, and with the help of the healthcare team, looked at trends and patterns and responses of glucose to insulin and made changes in carbohydrate to insulin ratios and basal rates. Patients who used the Bolus Wizard calculator did best and avoided hypoglycemia. It can also be said to the contrary that a lot has been learned from patients who do not benefit as much of the time: patients who did not wear the sensor at least 50 percent of the time; patients who did not trust the readings, and therefore did not look at the sensor; and patients who became extremely frustrated with nuisance alarms, causing them to stop using the sensor.

So patient behavior during wearing CGM is also a key factor to achieve a better outcome.

Are bolus amounts appropriate?Meal dosesCorrection dosesHow long do boluses work?What is the magnitude of postprandial spikes?Is basal insulin holding BG steady?

Objectives-Based Analysis

Are asymptomatic lows occurring?Are there rebounds from lows?Are lows being over/under treated?How does exercise affect BG?ImmediateDelayed effectsIs amylin/GLP-1 doing the job?Objectives-Based Analysis

How do various lifestyle events affect BG?Hi-Fat mealsUnusual foodsStressIllnessWork/SchoolSexAlcohol

Objectives-Based Analysis

These Are a Few of My Favorite

Stats

Mean (avg) glucose% Of Time Above, Below, Within Target RangeStandard Deviation# Of High & Low Excursions Per Week

23Case Study 1a: Fine-Tuning Meal/Correction Boluses

Breakfast and lunch doses may be too low Dinner dose appears OKGlucose (mg/dL)4003002001000 3 AM 6 AM 9 AM 12 PM 3 PM 6 PM 9 PM Night-snack dose clearly insufficient34-y.o. pump user

Case Study 1b: Fine-Tuning Meal/Correction Boluses Dropping low 2-3 hours after dinner.Consider decreasing dinner bolus. 5-year-old on MDI; levemir BID.

Case Study 1c: Fine-Tuning Meal/Correction Boluses BG Rising 9pm-1am.Consider structured night snacks with increased bolus amount.Teenager on a pump; stays up late.

Case Study 1d: Fine-Tuning Meal/Correction Boluses

Pumper, dropping low after correcting for highs during the nightCorr.BolusConsider increasing nighttime correction factor / insulin sensitivityCase Study 2a: Postprandial AnalysisYoung adult on MDI. HbA1c are higher than expected based on SMBGTired and lethargic after mealsSignificant postprandial spikes (300s). Consider pramlintide before meals.

Glucose (mg/dL)400300200100MealMealMealMealCase Study 2b: Postprandial AnalysisPump user, usually bolusing right before eating. Potatoes w/dinner most nights.

Spiking primarily after dinner. Consider lower g.i. food or pre-bolusing.

Case Study 2c: Postprandial AnalysisPump user, 6 months pregnantPre-bolusing (15-20 min) at most meals.Spiking primarily after breakfast. Consider splitting breakfast or walking post-bkfst.

Case Study 3a: Basal Insulin RegulationPump user, 6 months pregnantGenerally not eating (or bolusing) after 8pm.BG rising 1am-6am. Consider raising basal insulin 12am-5am.Case Study 3b: Basal Insulin Regulation

Glucose (mg/dL)4003002001000 3 AM 6 AM 9 AM 12 PM 3 PM 6 PM 9 PMBasal dose is likely too high. Consider reducing.Type 1 diabetes; using insulin glargine & MDIHistory of morning lowsSnacking at night and not covering w/bolusCase Study 4: Determination of Insulin Action Curve

3-Hour Duration5-HourDuration4-Hour Duration

12am 3am 6am

Case Study 5: Detection of Silent HypoglycemiaType1 college student; on pumpFrequent fasting highs (9-10 AM). Wanted to raise overnight basal rates.Dropping & rebounding during the night. Consider decreasing basal in early part of night.

Case Study 6: Effectiveness of Amylin/GLP-115 mcg pramlintide60 mcg pramlintide

Case Study 7: Response Curve to Different Food TypesPostprandial peak: cereal > oatmeal > yogurtCerealOatmealYogurtCase Study 8a: Responses to Lifestyle Events (stress)Type 1 diabetes; pump user40 years old; athleticHandsome, excellent speaker

Gets flat tire; eats 15g carbs to prepare for tire changeSpare is flat too!!STRESS CAN RAISE BLOOD GLUCOSE A LOT!!!Late for meetingGlucose (mg/dL)40030020010009 AM 12 PM 3 PM 6 PM 9 PM

Case Study 8b: Responses to Lifestyle Events (exercise)Experiencing delayed-onset hypoglycemia from heavy workouts. Consider temp basal reduction.Pump userBasal rates confirmed overnightyellow night: light cardio workout prior eveningRed night: Lifting & cardio workout prior evening

Case Study 8c: Responses to Lifestyle Events (dining out)Delayed rise from high-fat meals. Consider using temp basal increase.

Saturday Nights, Dinner Out

Pump userNormal fasting readings during the week, but high on weekendsIngredients For SuccessHave the right expectationsWear the CGM at least 90% of the timeLook at the monitor 10-20 times per dayDo not over-react to the data; take IOB into accountAdjust your therapy based on trends/patternsCalibrate appropriatelyMinimize nuisance alarms40In clinics that have utilized the MiniMed Paradigm REAL-Time System in studies, certain experiences can be gained. An analysis of patients who did well experienced benefits from using it continuously or at least 90 percent of the time. Patients who have experience with insulin pump therapy seemed to benefit more than those who were new to pump therapy and therefore still learning how to optimize their insulin pump usage. Patients who looked at it frequently, almost 10-20 times per day, but did not overreact to the data. Patients who had their CareLink data examined by the healthcare team, and with the help of the healthcare team, looked at trends and patterns and responses of glucose to insulin and made changes in carbohydrate to insulin ratios and basal rates. Patients who used the Bolus Wizard calculator did best and avoided hypoglycemia. It can also be said to the contrary that a lot has been learned from patients who do not benefit as much of the time: patients who did not wear the sensor at least 50 percent of the time; patients who did not trust the readings, and therefore did not look at the sensor; and patients who became extremely frustrated with nuisance alarms, causing them to stop using the sensor.

So patient behavior during wearing CGM is also a key factor to achieve a better outcome.

Questions?