HbA 1c will remain the preferred marker for assessing glycaemic control

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1 HbA 1c will remain the preferred marker for assessing glycaemic control Garry John Norfolk and Norwich University Hospital & The Norwich Medical School, UEA UK

2 Will HbA 1c remain the preferred marker for assessing glycaemic control? Undoubtedly YES

3 History of Diabetes Investigations 1679: Willis Urine of diabetics had a sweet taste Associated with: "good fellowship and guzzling down of... wine." 1776: Dobson Isolated a dry residue from urine of diabetics which looked and tasted like brown sugar

Laboratory glucose measurement - Daily fluctuations Glucose

0 x Biological variations from day to day can lead to a

5 x x The same patient can achieve genuine FPG results of 6.

4 Laboratory glucose measurement - Daily fluctuations Glucose mmol/l x Biological variations from day to day can lead to a patient s FPG varying by as much as 12-15% x x The same patient can achieve genuine FPG results of 6.5, 7.0 and 6.0mmol/l Classification could be IGT or Diabetes or normal, depending on the day of the appointment!

5 Glucose (mmol/l) Lab glucose measurement - Sample deterioration Changes in Glucose Concentration with Time Fluoride vs. Heparin 6.8 WHOLE BLOOD F H Time (min) (hr) Chan Clin Chem 1989; 35: 315

7 Evidence for HbA 1c to remain the preferred marker for assessing glycaemic control HbA 1c Evidence Biochemical Good Scientific Evidence Analytical Undisputable Clinical Standardisation Evidence Quality All Others Evidence Little Evidence Lack of Evidence No Evidence

8 HAEMOGLOBIN A 1c THE EVIDENCE Biochemical Evidence

9 An abnormal haemoglobin in red cells of diabetics Rahbar S Clin Chim Acta 1968; 22:

10 The Evolution of the understanding of HbA 1c Biochemistry 1955: Kunkel and Wallenius: First description 1957: Rhinesmith et al: abnormality present in the N-terminal of the b-chain 1958: Allen et al: resolved HbA 1 into three fractions HbA 1a, HbA 1b and HbA 1c 1966: Holmquist and Schroeder: concluded that HbA 1c is the condensation product (Schiff base) of HbA 0 and a ketone or an aldehyde 1968: Bookchin and Gallop: suggested that the N-terminal structure of the HbA 1c globin to be N-1-(deoxyhexitol)-valine 1975: Bunn et al: glucose reacted initially with the amino terminus to form an aldimine linkage; subsequently undergoing an Amadori rearrangement to form a stable ketoamine 1979: Bunn et al: indicated that the extent of Amadori rearrangement of newly synthesised HbA 1c was 60% by 6 days and 91% by 22 days

11 Haemoglobin A 1c α-chain β-chain HbA1c β-chain α-chain Naam

12 IFCC/IUPAC Committee on Nomenclature, Properties and Units (C-NPU) Scientific name for N terminal glycation of haemoglobin: Haemoglobin beta chain (Blood) N-(1- deoxyfructos-1-yl) haemoglobin beta chain

13 HC O HC N b A CH 2 NH b A CH 2 N + H 2 b A b Hb HCOH H 2 N + HOCH HCOH HOCH Amadori rearrangement C HOCH O H + C HOCH O HCOH HCOH HCOH HCOH HCOH HCOH HCOH HCOH CH 2 OH CH 2 OH CH 2 OH CH 2 OH Aldimine (Schiff base) Ketoamine HC OH HC NH b A H 2 C NH b A H 2 C N + H 2 b A HCOH HOCH HCOH HOCH COH HOCH H + COH HOCH HCOH O HCOH O HCOH O HCOH O HC HC HC HC CH 2 OH CH 2 OH CH 2 OH CH 2 OH Glucose b N valyl 1 deoxyglucose b N valyl 1 deoxyfructose A Non-enymatic reaction following the Law of Mass Action.

14 What Period is Measured? Test at end May Total influence of monthly blood glucose on HbA 1c May 6.25% April May 8.33% April May 12.5% May 25.0% May 52% April 27% March April March 14.5% Feb March Feb 6.5% February March April May Month red blood cell produced

15 ANALYTICAL EVIDENCE Reference Measurement System Metrological requirements: Identification of the Measurand Reference Measurement Procedure Reference materials / laboratories Traceability

16 Haemoglobin Haemoglobin concentration concentration dialysis boronate chromatography dialysis boronate chromatography dialysis dialysis SP-Sepharose HP chromatography SP-Sepharose HP chromatography Pool fractions acc. Molar mass Pure HbA 1c Pure HbA 0

17 Reference Method Blood Erythrocytes Hemolysate Enzymatic Cleavage Quantify Specific Peptides Method A HPLC Mass Spectrometry Method B HPLC Capillary Electrophoresis

18 Clin Chem 2004; 50:

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19 Albania Argentina Australia Austria Belgium Bosnia Erzegovina Brazil Canada China P.R. China-Taipei Colombia Costa Rica Croatia Cuba Denmark Ecuador Egypt Estonia Finland France Germany Guatemala Honduras Hong Kong Hungary Iceland India Iran Ireland Israel Italy Japan Jordan Kenya Korea Macedonia Kuwait Malaysia Latvia Mexico Lebanon Morocco Netherlands Lithuania Nigeria Luxemburg Norway Pakistan Paraguay Poland Portgual Romania Russia Serbia & Montenegro Singapore Slovak Rep. Slovenia South Africa Thailand Spain Switzerland Syrian Arab Rep. Tunisia Sweden Turkey U.K. U.S.A. Uruguay Vietnam Bulgaria Czech Rep. Greece Indonesia Chile

20 Clin Chem 2008 The IFCC Reference Measurement System for HbA1c: A 6-Year Progress Report Cas Weykamp (1*), W. Garry John (2), Andrea Mosca (3) Tadao Hoshino (4), Randie Little (5), Jan-Olof Jeppsson (6) Kor Miedema (8), Gary Myers (9), Hans Reinauer (10) David Sacks (11), Robbert Slingerland (8), Carla Siebelder (1)

21 IFCC Network Labs NL NL US US US DE FR IT DE CN IN CN CN KR JP JP JP BR ACCURACY December 2016 Approved

22 Big Mac Available in over 120 countries: Approx 500kcal Outliers: USA; South Africa; Japan and Mexico

23 Global Calibration of HbA 1c Primary reference materials (IRMM 466 and 467) Secondary reference materials (blood panels) IFCC reference measurement procedure (HPLC-CE or HPLC-MS) IFCC Network Manufacturer s working calibrator Manufacturer s product calibrator Manufacturer s internal reference measurement procedure Manufacturer s standing measurement procedure Manufacturer Patient Sample Routine measurement procedure Individual laboratory

24 Haemoglobin A 1c Metrological Traceability White GH. Ann Clin Biochem 2011; 48:

25 All other Markers Metrological Traceability White GH. Ann Clin Biochem 2011; 48:

26 METHODOLOGICAL EVIDENCE Major method principles for HbA 1c Cation Exchange HPLC Capillary Electrophoresis Affinity Chromatography HPLC Immunoassay Enzymatic Method options >100 methods/platforms available >20 international manufacturers (many more National)

27 1971: Trivelli et al First clinically useful technique using mini-columns resulting in a clinically useful method. Measured total HbA 1

28 Cation-Exchange HPLC

29 Capillary Electrophoresis HbAS Patient

30 Affinity Chromatography

31 Immunoassay HbA 1c Antibody 4 amino acids

Enzymatic assay Pretreatment: In the pretreatment process, the erythrocytes are lysed and the

1st Reaction: glycated N-terminal dipeptide of the β-chain of haemoglobin is cleaved by the action

The concentration of the haemoglobin is measured by absorbance.

32 Enzymatic assay Pretreatment: In the pretreatment process, the erythrocytes are lysed and the hemoglobin is transformed to methemoglobin by reaction with sodium nitrite. 1st Reaction: glycated N-terminal dipeptide of the β-chain of haemoglobin is cleaved by the action of protease. The Hb is stabilised by adding of sodium azide. The concentration of the haemoglobin is measured by absorbance. 2nd Reaction: FPOX is added to Fructosyl Dipeptide to produce Hydrogen Peroxide. The Hydrogen Peroxide reacts with the colouring reagent. Absorbance is measured at 660nm to calculate HbA 1c concentration. Naam

33 QUALITY EVIDENCE

34 A Project of IFCC C-EUBD Education in the Use of Biomarkers in Diabetes & 15 National EQA organisers EurA1c Garry John Emma English Rajiv Erasmus David Sacks Cas Weykamp

35 Participants First EurA1c in October 2016

36 BE WIV-ISP Yolande Lenga DE INSTAND e.v. Patricia Kaiser GR ESEAP EQA Organisers Alexander Haliassos, Kostas Makris, Otto Panagothinakis IT Centro di Ricerca Biomedica Laura Sciacovelli CZ SEKK Marek Budina, Marie Uhlířová FR Biologie Prospective Jean-Pascal Siest SA Tygerberg Hospital Rajiv Erasmus UK WEQAS Annett Thomas, Samantha Jones SE EQUALIS Gunnar Nordin, Carita Krook Persson AT ÖQUASTA Christoph Buchta, Mathias M. Müller ES SEQC Montserat Ventura, Emma Ventura PT Inst. Nac. de Saude Dr. Jorge Ana Paula Faria IE IEQAS Hazel Graham CH Universitätsspital Zürich Roman Fried TR Tubitak Ume Diler Aslan, Fatma Akcadag, Muslum Akgoz NL SKML Cas Weykamp INT ERL Cas Weykamp

37 Bias (0.09) (0.18) (0.28) ( 0.37) (0.46) (NGSP) IFCC Performance per Country Fresh Whole Blood Accuracy unbelievably good Imprecision needs improving. Overall mean IE UK BE NL FR SE IT DE CH TR IFCC (0.7) (1.4) (2.0) (2.7) (3.4) (NGSP) Imprecision in CV in %

38 Bias (0.09) (0.18) (0.28) ( 0.37) (0.46) (NGSP) IFCC EurA1c Trial 2016 (Fresh Whole Blood) Performance per Manufacturer N = 1514 laboratories Overall mean O A B a c f W g N b E C Q e Y G T J F V D IFCC (0.7) (1.4) (2.0) (2.7) (3.4) (NGSP) Imprecision in CV in %

39 Bias (0.09) (0.18) (0.28) ( 0.37) (0.46) (NGSP) IFCC CAP Survey GH5-12 A Min Des Opt α W Y N I H V G P T S M F K E C D X IFCC (0.7) (1.4) (2.0) (2.7) (3.4) (NGSP) Q Between Laboratory CV in % R L US B Z O J U

41 Haemoglobin A 1c and: The Doctor CLINICAL EVIDENCE

42 Relative Risk DCCT: HbA 1c and risk of microvascular complications Retinopathy HbA 1c (%) Nephropathy Neuropathy Microalbuminuria Skyler. Endocrinol Metab Clin 1996;25: Diabetes Control and Complications Study (DCCT)

43 HbA 1c direct relationship with outcome UKPDS showed that HbA 1c is the best long-term marker of diabetes control 21% Deaths related to diabetes HbA 1c 1% 37% Microvascular complications Microvascular complications Better control of HbA 1c leads to better outcomes in people with diabetes 14% Myocardial infarction Stratton IM, et al. BMJ 2000; 321: United Kingdom Prospective Diabetes Study (UKPDS)

44 HbA 1c direct relationship with outcome DCCT & UKPDS showed that HbA 1c is the best long-term marker of diabetes control 21% Deaths related to diabetes HbA 1c HbA 10 1c mmol /mol 1% 37% Microvascular complications Microvascular complications Better control of HbA 1c leads to better outcomes in people with diabetes 14% Myocardial infarction Stratton IM, et al. BMJ 2000; 321: United Kingdom Prospective Diabetes Study (UKPDS)

45 WHY HAEMOGLOBIN A 1c? Haemoglobin A 1c has been used in clinical practice for over 45 years Results are fully understood by Doctors and Patients Clinical Guidelines are based on this measurement. Diagnosis is based on this measurement.

46 Standardised HbA 1c has enabled: Patient Safety Patient Empowerment Public Confidence Accreditation Clinical Guidelines Clinical Governance Consolidation & Networking Informatics Electronic Patient Record Dr. Graham Beastall, Past President IFCC and Chair JCTLM WG Traceability Adapted from Plebani, Clin Chem Lab Med 2013; 51:

47 The Evolution of HbA 1c in Clinical practice Discovery of a new Hb fraction Recognition in clinical medicine DCCT and UKPDS Standardisation of results Standardisation allows target setting Standardisation allows used for diagnosis Recognition of individual variation Individual treatment goals

48 The Future: Who Knows? But: Haemoglobin A 1c will remain the glycaemic marker of choice for the foreseeable future.

49 THANK YOU

EU Market Situation for Poultry. Committee for the Common Organisation of the Agricultural Markets 20 April 2017

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