Glucose Monitoring Is it Worth It?

Self Monitoring of Blood Glucose &Continuous Glucose Monitoring

Joe Largay, PAC, CDEClinical Instructor

Department Of MedicineUniversity Of North Carolina

jlargay@med.unc.edu

Learning Objectives:• Explain how to use glucose monitoring to self

empower your patients with diabetes to improve their glycemic control

• Compare and contrast Self Monitoring of Plasma Glucose (SMPG) and Continuous Glucose Monitoring (CGM)

• List the benefits of Self Monitoring of Plasma Glucose (SMPG)

• Describe how to use SMPG to identify glycemic patterns

Major Barriers to Achieving Glycemic Goals

• Behavioral change

• Lack of awareness of glycemic levels

• Fear of hypoglycemia

Hirsch IB, et al. Diabetes Technol Ther. 2008;10(4):232-246.

Global Attitudes of Patients and Physicians in Insulin Therapy (GAPP™) • Fear of Hypoglycemia

– 67% of patients– 74% providers

• 67 % feel that diabetes has controlled their life since starting insulin

• 1 in 3 patients skip insulin doses at least 3 times per month – Too busy– Change in normal routines– Forget to take

Hypoglycemia and CV Disease

• ACCORD: Symptomatic, severe hypoglycemia was associated with an increased risk of death whether participants were in the intensive arm or the standard arm1

• Patients with hypoglycemic events had 79% higher regression-adjusted odds of acute cardiovascular events, than patients without (odds ratio [OR] 1.79; 95% CI 1.69–1.89)

1. BMJ 2010; 340:b4909 2.Diabetes Care 34:1164–1170, 2011

ACCORD-Determinants of Hypoglycemia

• Rates of severe hypoglycemia were more common in the intensive as compared to the standard group (3.14% vs. 1.03%)

Highest rates seen in :• African-Americans• Older participants• On insulin therapy at trial entry• Women• Lower levels of educational achievement• Higher baseline A1c • Greater lowering of A1C during the first 4 months was associated with

lower risk of severe hypoglycemia

Miller, M. et al, 8 January 2010, doi:10.1136/bmj.b5444

Type 2 DM and CV Disease Risk Reduction: Lessons From ADVANCE, ACCORD, VADT, & UKPDS

• Achieve better blood glucose levels to prevent microvascular complications in patients earlier in the course of their diabetes

• Individualize glucose goals for patients with advanced CVD– In older, high-risk patients with CVD, maintain A1C close to 7%, not

necessarily <7%• Use more intense blood glucose control to modestly reduce CVD risk in

those with early DM w/o advanced atherosclerotic disease. In these individuals, an A1C target of 6.5% or less may be appropriate

• Avoid hypoglycemia• Focus also on lipid lowering, BP reduction, antiplatelet therapy,

smoking cessation, and antihyperglycemic agents

Individualizing Treatment Goals

Goals should be individualized based on:● duration of diabetes● age/life expectancy● comorbid conditions● known CVD or advanced microvascular complications● hypoglycemia unawareness● individual patient considerations● More or less stringent glycemic goals may be appropriate for individual patients.● Postprandial glucose may be targeted if A1C goals are not met despite reaching preprandial glucose goals.

Measures of SuccessA1C • provides the “big picture” - the average glycemia levels

during previous 90 days (but is more heavily weighted by the most recent values) and correlates with end-organ impact

SMBG (Self Monitoring of Blood Glucose)• patterns provide day-to-day data used to select and manage

glucose control programs and ultimately optimize A1C:– Provide a measure of the specific pharmacologic impact of

oral treatment medications– Allow design and implementation of physiologic insulin-

replacement programs

ADA. Diabetes Care 2011:34(S1):S11-S61Rodbard HW et al, Endo Pract. 2007; 13:1-68

Goal

Premeal capillary plasma glucose (mg/dl)

Peak postprandial capillary plasma glucose

HbA1c

ADA

70-130

<180*

ACE

<110

<140

2011 Glycemic Goals of Therapy

*A reasonable recommendation for postprandial testing and targets is that for individuals who have premeal glucose values within target but have A1C values above target, monitoring postprandial plasma glucose (PPG) 1–2 h after the start of the meal and treatment aimed at reducing PPG values to 180 mg/dl may help lower A1C.

< 7% < 6.5%

SMBG – Part of Self Management Skills

Is SMBG Beneficial?

Polonsky WH, Fisher L, Schikman CH, et al. Structured self-monitoring of blood glucose significantly reduces A1C levels in poorly controlled, noninsulin-treated type 2 diabetes. Diabetes Care. 2011;34(2):262-267.

Is SMBG Beneficial?

Polonsky WH, Fisher L, Schikman CH, et al. Structured self-monitoring of blood glucose significantly reduces A1C levels in poorly controlled, noninsulin-treated type 2 diabetes. Diabetes Care. 2011;34(2):262-267.

Limitations and Potential Errors with SMBG

• Sample contamination (dirty hands)• Insufficient blood on strip• Incorrect insertion of strip into meter• Outdated strips• Failure to perform quality control• Incorrect strip code entered in meter• Incorrect units of measure (mg/dl vs. mmol)

Limitations and Potential Errors with SMBG

• Altitude (6.5-15% variability)• Temperature• Hematocrit (inverse relationship)

Self Monitoring Blood Glucose Log

Fasting Lunch Before Soccer Practice

Supper Bed 2 am

99 187 182 67 182 105

84 211 192 123 105 56

202 143 259 75 236 158

107 181 178 94 127 64

Self Monitoring Blood Glucose LogPaired Readings

Fasting After

Breakfast

Before

Lunch

After

Lunch

Before

Dinner

After

Dinner

101 132

87 267

97 158 286

189 131 304

85 222

SMBG LogT2DM on Prednisone

Time of Day Before start of Prednisone After start of Prednisone

Before Breakfast 77-119 178-225

Before Lunch 95-136 191-249

Before Supper 105-141 287-409

Bedtime 116-156 261-293

“c/o increased urination and feeling tired late in the day since starting steroids”

The Role of Continuous Glucose Monitoring (CGM)in the Management of Diabetes

The Devil is in the DetailsJoe Largay, PAC, CDE

Clinical InstructorDepartment of MedicineDivision of Endocrinology

University of North Carolina

With SMBG, Diabetes Patients Are Essentially Blindfolded

Simple Carbs

Blood Glucose Levels

Fast

Gastroparesis

constipationinsomnia

exposure to cold

menstruationillness

medicationemotionstress

time changecaffeine

smoking

French Meal

Fatty MealComplex Carbs

Slow Very Slow

Still there the next

day

See French Meal

Exercise

Rapid

DigestionBrain Function

2% of body mass, 25% of glucose consumption

Variable Sustained

All these variables play a role in daily glucose control and … every day is a different day.

All these variables play a role in daily glucose control and … every day is a different day.

Real-Time Continuous Glucose Monitoring (CGM) Systems

Abbott FreeStyle Navigator®

DexCom™ SEVEN®

PLUSMedtronic MiniMed

Paradigm® REAL-Time Revel™

SMBG Does Not Give Patients the Whole Picture

0

70

140

210

280

350

2 4 6 8 10 12 14 16 18 20 22 24Time (Hours)

Glu

cose

(mg/

dL)

0

Based on simulated data. Based on simulated data.

CGM Systems1-4

Currently most CGM systems use an electrochemical process for glucose sensing

Three major CGM devices have been approved by the FDA

All available CGM devices read glucose values in the Interstial Fluid Space (ISF)

1. FreeStyle Navigator® Product Fact Sheet. Abbott Diabetes Care; 2008. 2. FreeStyle Navigator® Product Brochure. Abbott Diabetes Care; 2007.

3. Paradigm® REAL-Time User Guide. Medtronic MiniMed; 2007.4. SEVEN® User’s Guide. DexCom; 2009.

What Is Calibration?

• Sensor calibration is the pairing of the fingerstick (FS) value to the sensor value from the interstitial fluid (ISF) space− FS measures plasma-calibrated blood− Sensor reads electrical current produced by glucose oxidase

reaction− Calibration confirms sensor accuracy during various points by

“teaching” the sensor the glucose value that corresponds with the electrical current signal

− Calibration is how the device learns what the signals from the sensor mean

Velho G, et al. Biomed Biochim Acta. 1989;48(11-12):957-964.

Comparison Matrix – Sensor

DexCom™ SEVEN® PLUS1

Medtronic Paradigm® REAL-Time2

Abbott FreeStyle

Navigator®3

Sensor length 13 mm 14 mm 5 mm

Sensor introducer needle4 26 gauge 23 gauge 21 gauge

Sensor wear Up to 7 days Up to 3 days Up to 5 days

Sensor start-up 2 hours 2 hours 10 hours

Sensor sites Abdomen Abdomen Abdomen, arm

Sensor packaging 4 packs 4 and 10 packs 6 pack

Glucose rangeCalibration range

40-400 mg/dL40-400 mg/dL

40-400 mg/dL40-400 mg/dL

20-600 mg/dL60-300 mg/dL

Insertion angle 45° 45° 90°

1. SEVEN® User’s Guide. DexCom; 2009. 2. Paradigm® REAL-Time User Guide. Medtronic MiniMed; 2007.3. FreeStyle Navigator® Users Guide. Abbott Diabetes Care; 2008.

4. Diabetes Health. 2008;Dec 08/Jan 09:28-29. http://digital.diabetes health.com/read/08/12/29.html. Accessed January 19, 2009.

Product Price Comparisons 2011

DexCom™ SEVEN® PLUS

Medtronic Paradigm® REAL-Time

Abbott FreeStyle Navigator®

Starter kit list price $1158 $1200 $1250 ??

Sensor cost/day $17 $12 $15 ??

CGM Supports Patients in Proactive vs Reactive Self-Management

Helps to warn of impending hypoglycemia or hyperglycemia

Alerts/alarms help patient “stay between the lines”

Helps detect nocturnal events

Helps provide immediate feedback re: how changes in diet, exercise, stress, and insulin affect glucose levels

May help avoid overreaction and/or overtreatment of high or low glucose values by alerting to impending highs and lows

Supports pattern management

Tracking/trending provide series of multiple sequential glucose readings over time, can aid in diabetes self-management decisions

53-year-old male, multiple injector; 240 lbs.; 10 yrs. diabetes; HbA1c 7.3

0

100

200

300

400

0 1440 2880 4320 5760 7200

Glu

cose

(mg/

dl)

Day 68 Day 69 Day 70 Day 71 Day 72

4.3h

7.6h 5.6h1.3h

Max.Sensor Reading

364 362

368 350 367 Undetected High Excursions With SMBG

0.5h1.0h

2.9h

0.9h

This patient seldom recovers from breakfast until the end of the day

CGM Can Uncover Glucose Patterns That May Be the Cause of a High A1c

Data on file, DexCom. Study Number G1-02-01; RPT 2168. Data on file, DexCom. Study Number G1-02-01; RPT 2168.

CGM Professional

• Purchased and used in clinics• Reimbursable• Clinicians can download data and review with

patient

CGM Can Help Clinicians Help Patients

Provides insight into trending information/pattern management Basal testing Insulin on-board testing Insulin-to-carbohydrate and correction dose testing Insulin on-board timing

Identifies insulin action (insulin dose effect) and potential need for additional medication to control postprandial glucose

Provides information about timing of food digestion and timing of insulin administration based on food absorption

Provides continuous data for overnight basal testing and assessment of any nocturnal hypoglycemia

CGM Indications

• Indicated for ages > 18 for use in addition to SMBG for the purpose of improving glycemic control

• Supported by ADA and AACE Guidelines for glucose monitoring

• To identify and aid in management of glycemic patterns not recognized with typical SMBG

• To prevent glycemic excursions:– hypoglycemia– hyperglycemia

CGM is NOT

Technology that can be used to dose insulin All dosing decisions should be based on the SMBG

Replacement for glucose meter (SMBG)

Device to put on and “forget” about Studies have shown a correlation between the

number of times you look at the receiver and greater reduction in A1c1

System that replaces/is a substitute for already existing diabetes management tools

Bailey TS, et al. Diabetes Technol Ther. 2007;9( 3):203-210.Bailey TS, et al. Diabetes Technol Ther. 2007;9( 3):203-210.

Continuous Glucose Monitoring andIntensive Treatment of Type 1 Diabetes

(The Juvenile Diabetes Research Foundation Continuous Glucose Monitoring Study Group*)

• In age group > 25 years old a decrease in A1c without increase in severe hypoglycemia

• This was not seen in younger age groups 8-14 or 15-24

• Success in lowering A1c correlates with individuals’ ongoing use of CGM– Patients who used CGM 6 days/week experienced a minimum of 0.5%

reduction in A1c2

– Greatest predicator of A1c lowering in the JDRF trial for all ages was frequency of sensor use

NEJ M 2008;359

CGM: Clinical Indications

Glycemic variability• Hypoglycemia• Hypoglycemia unawareness• Gastroparesis• Preconception• Behavior modification• Insulin-requiring DM

Hirsch IB, et al. Diabetes Technol Ther. 2008;10(4):232-246.

Example of Patient With Hypoglycemia

Overcorrection of high blood glucose and overtreatment of low blood glucosecould be minimized by use of CGM.

Data on file; DexCom.

Example of Response to Food

Patient hesitant to give more insulin before eating—untilCGM showed her how high her numbers were traveling after eating a meal.

Data on file; DexCom.

Bike (56.4)

Swim

(1.2)

Run (13.1)

35 yo Female on Sensor Augmented Insulin Pump TherapyLonghorn 70.3 mile Triathlon – October 25, 2009

Use of CGM During Pregnancy Improves A1c Outcomes

Voelmle---Garg: Diabetes, 57, 2008Voelmle---Garg: Diabetes, 57, 2008

A1c levels during pregnancy

*p < 0.001 within groups from BL

6.80

5.89

7.05

6.416.46

5.95

5.82

5.73

5.95

6.26

6.11

6.19p < 0.03

p = 0.20

p = 0.15

p = 0.13

p = 0.09

p = 0.41

5.60

5.80

6.00

6.20

6.40

6.60

6.80

7.00

7.20

Baseline 3 M 4 M 5 M 6 M 7 M

Gestational Month

A1c

%

Comparison

RTCGM group

Voelmle---Garg: Diabetes, 57, 2008

Current Reimbursement Environment With CGM

• A number of national and local payers have issued a positive coverage decision for the personal use of continuous glucose sensors

• Other decisions remain on a case-by-case basis for some of the national payers; cash-pay is also an option

• If patients purchase up-front, claims can be submitted by the patient to the insurance carrier for review and authorization

• Can use Flexible Spending Accounts for purchase of a CGM device

General Reimbursement Criteria for Personal Use of CGM

• Some insurance plans require only basic criteria of patients needing to have type 1 diabetes and be over the age of 25 (e.g. Aetna)

• Other insurance plans require more specific criteria of either some or all of the below criteria:– Type 1 diabetes– Using either multiple daily injection (MDI) or continuous insulin

infusion (CSII)– SMBG ≥4/day– Recurring hypoglycemia– Being seen by an endocrinologist – Not meeting ADA glucose guidelines goal of A1c <7%

2009 CGM Coding ReferenceDescription RVU1 Medicare2

Physician Fee Schedule

Medicare3 Outpatient Diabetes Center

Private Payer4

95250Ambulatory CGM of ISF via a subcutaneous sensor for a minimum of 72 hrs; sensor placement, hook-up, calibration of monitor, patient training, removal of sensor, and printout of recording

3.56 $128 $106

(APC 0607)

$310

95251Ambulatory CGM of ISF via a subcutaneous sensor for a minimum of 72 hrs; interpretation and report. Do not report more than once per month

1.10 $40 Paid under physician fee schedule

$54

Evaluation and Management (E/M) Codes

99212-99215Established Patient Visit

1.03-3.46

$37-$125 $23-$98 $62-$187

1 CMS Federal Register (November 2008)

2 CMS Federal Register (November 2008) Medicare fee schedule for services in MD office. The fee schedule is not geographically adjusted.

1 CMS Federal Register (November 2008)

2 CMS Federal Register (November 2008) Medicare fee schedule for services in MD office. The fee schedule is not geographically adjusted.

3 CMS Federal Register (November 2008). Fee schedules for E/M codes are MD payment for services provided in a hospital outpatient facility.

4 PMIC Medical Fees in the US 2009. Numbers provided are 50% of the Usual and Customary charges. Note that these are charges and not actual reimbursed amounts.

3 CMS Federal Register (November 2008). Fee schedules for E/M codes are MD payment for services provided in a hospital outpatient facility.

4 PMIC Medical Fees in the US 2009. Numbers provided are 50% of the Usual and Customary charges. Note that these are charges and not actual reimbursed amounts.

What Pattern do you see?

1. Elevated Fasting readings

2. Overcorrection after meals

3. Normal fasting glucose but meal related excursions leading to elevated bedtime readings which correct overnight

CGM – Type 2 DMWhat Pattern do you see?

T2DM on Pre Mix Insulin BIDWhat pattern do you see?

1. Controlled but with frequent hypoglycemia

2. Uncontrolled with fasting hyperglycemia

3. Uncontrolled with both elevated fasting and postprandial excursions

4. Normal pattern

T1DM on PumpWhy are fasting glucoses high?

1. Patient is eating at bedtime

2. Nocturnal hypoglycemia with rebound high fasting glucose

3. Dawn phenomenon

Dawn phenomenonDawn phenomenon

Increase basal here at 12:00 a.m.

fastingfasting

Tracking and trending information/pattern management

Immediate feedback on how changes in diet, exercise, insulin affect glucose levels Event Markers can aid in this assessment

Reduction in hypoglycemia/hyperglycemia1,2

Help patients understand A1c by becoming aware of importance of assessing glycemic variability

Increase time in target range1,2

Help patients assess magnitude of glucose excursions1,2

1. Garg S, et al. Diabetes Care. 2006;29(1):44-50.2. Garg S, Jovanovic L. Diabetes Care. 2006;29(12):2644-2649.

Continuous Glucose Monitoring Summary

ConclusionsCurrent Treatment Targets for Glycemia

• Need to be individualized

• Be aggressive early in the course of the disease

• Treat other comorbidities

• Use caution with complicated patients

– Avoid hypoglycemia