DIABETES Use of the Estimated Average Glucose (eAG) in Patient Care Part 2 of 2

DIABETES ADAG Study: Glucose Monitoring CGM – mean of ~ 2,400 measurements per participant LifeScan meter ~ mean of 300 measurements per participant –Mean of ~ 25 measurements per week –Goal was a minimum of 21 tests per week Total ~ 2,700 measurements/participant during 12 weeks

DIABETES ADAG Study: Analyses CGM results corrected upward by 5% to be consistent with BG Each glucose measure weighted in proportion to the inverse of total number of measurements on that day (each day had equal weight) Arithmetic mean glucose calculated for each participant Linear regression model used to estimate relationship between average glucose and the 3-month HbA1c

DIABETES ADAG Study: Study Success 90% of values fell within +/- 15% 90% of values fell within +/- 15% Calc. AG (mmol/L) 90% of cohort values fall in this range HbA1c (%)

DIABETES ADAG Study: Correlation of AG With HbA1c AG (mg/dl) HbA1c (%) AG (mg/dl) = 28.7 x HbA1c – 46.7 R2 = 0.84 P <

DIABETES ADAG Study: Correlation of AG with HbA1c: CGM data vs. Meter HbA1c (%) No difference in relationship (P=0.18) whether LifeScan or CGMS data used

DIABETES ADAG Study: Other Factors Examined Does the HbA1c-Average Glucose relationship differ by:Does the HbA1c-Average Glucose relationship differ by: - Type 1 or type 2 diabetes NO - Type 1 or type 2 diabetes NO - Diabetes or no diabetes NO - Amount of glucose variability NO - Gender NO - Gender NO - Age NO - Age NO - Ethnicity/Race NO (but trend toward higher HbA1c per AG in African and African-American participants vs. whites, P=0.07) (but trend toward higher HbA1c per AG in African and African-American participants vs. whites, P=0.07) - Smoking NO - Smoking NO

DIABETES ADAG Study Excluded Known Sources of “Inaccuracy” of HbA1c Hemoglobinopathy Anemia Pregnancy Hepatic or renal disease Etc.

DIABETES ADAG Study Conclusion: HbA1c Correlates Highly With AG Measured HbA1c (%) AG (mg/dl) = 28.7 x HbA1c – AG (mg/dl)

DIABETES Tight correlation between HbA1c and AG allows us to translate HbA1c into an estimated Average Glucose (eAG)Tight correlation between HbA1c and AG allows us to translate HbA1c into an estimated Average Glucose (eAG) eAG will apply to the majority of patients with diabeteseAG will apply to the majority of patients with diabetes –Barring “traditional” conditions interfering with the assay or the relationship between glycemia and HbA1c Implications

DIABETES ADAG Study: “Translation” of HbA1c into eAG eAG HbA1c (%) (mg/dl)(mmol/l)_

DIABETES Note that the numbers are different ADAG DCCT HbA1c (%) (mg/dl)___(mg/dl)______

DIABETES Consensus Statement FCC, EASD, IDF, ADA Sept 2007) Diabetes Care and Diabetologia, 2007 HbA1c assay to be standardized worldwide using the new IFCC standard and expressed as: –% as currently used (DCCT values) –IFCC units in mmol HBA1c/mol HbA –eAG in mmol/l or mg/dL (if ADAG study meets its data acceptability goals) This paved the way for reporting both HbA1c and EAG on lab reports

DIABETES What Won’t Change…And What’s New To a clinician, there is no change in the HbA1c assay To clinical chemists, there is a new IFCC standard in the background We have the potential for a valuable educational tool for patients

DIABETES A Typical Patient Encounter “So, Mrs. Smith, it looks like you do have diabetes. Your average blood sugar is around 200. When people don’t have diabetes, this number is below 125. We need to work with you to try to get this number, the average glucose, down below 150 over the next few months with some weight loss, exercise, and a medication. Let’s talk some more about what you can do…”

DIABETES “Wow, I’m not happy to hear that…I know that diabetes can do some bad things. Tell me what I can do to get my average glucose down.” A Typical Patient Encounter

DIABETES What is ADA Doing to Promote Use of eAG in Patient Care? Health care provider education –ADA Scientific Sessions, June ’08 –American Association of Clinical Chemists, August ‘08 –AADE Annual Meeting, August ‘08 –eAG calculators (handheld and on professional.diabetes.org) Patient education –Website –Diabetes Forecast magazine, books –Pamphlets and brochures –ADA will include term “average glucose” in all consumer pieces

DIABETES What Can Clinicians and Educators Do? Choose which term—A1C or Average Glucose— to use with each patient (some may already be used to A1C) In verbal communications, no need to say “estimated” We want to keep the A in A,B,Cs Use updated table, calculator on or other tools to convert A1C to average glucose “Lobby” your lab to report both numbers

DIABETES What Can Clinical Chemists Do? Even with tools, most clinicians will not take the time to calculate conversions Reporting both HbA1c (DCCT-aligned) AND eAG on lab reports will do the most to promote wide use of the term Professional and patient education may drive demand Conversion is a simple regression equation

DIABETES Average Glucose Blood pressure Cholesterol to help make the “A” understandable!