Lori Berard|Rick Siemens|Vincent Woo
Monitoring Glycemic Control
key messagesglycated hemoglobin a1c valuable indicator glycemic treatment effectiveness measured least every 3 months glycemic targets met antihyperglycemic therapy adjusted circumstances significant changes made therapy pregnancy appropriate check a1c frequentlyawareness measures glycemiaselfmonitored blood glucose results including selfmonitored blood glucose smbg flash glucose monitoring fgm continous glucose monitoring cgm a1cprovides best information assess glycemic controlselfmonitoring blood glucose fgm cgm viewed glucoselowering interventions rather aids assess effectiveness glucoselowering interventions prevent detect hypoglycemiatiming frequency smbg may determined individually based type diabetes type antihyperglycemic treatment prescribed need information blood glucose levels individuals capacity use information testing modify healthy behaviours selfadjust antihyperglycemic agentssmbg fgm cgm linked structured educational therapeutic program designed facilitate behaviour change improve blood glucose levels prevent hypoglycemiakey messages people diabetesa1c measurement average blood glucose control last 2 3 months approximately 50 value comes last 30 daysyou a1c measured every 3 months blood glucose targets met making changes diabetes management circumstances significant changes made glucoselowering therapy pregnancy healthcare provider may check a1c frequentlychecking blood glucose glucose meter also known selfmonitoring blood glucose using flash glucose meter continuous glucose monitor willdetermine high low blood glucose given timeshow health behaviours diabetes medications affect blood glucose levelshelp diabetes healthcare team make health behaviour medication changes improve blood glucose levelsdiscuss diabetes healthcare team often check blood glucose level glycated hemoglobin a1c valuable indicator glycemic treatment effectiveness measured least every 3 months glycemic targets met antihyperglycemic therapy adjusted circumstances significant changes made therapy pregnancy appropriate check a1c frequentlyawareness measures glycemiaselfmonitored blood glucose results including selfmonitored blood glucose smbg flash glucose monitoring fgm continous glucose monitoring cgm a1cprovides best information assess glycemic controlselfmonitoring blood glucose fgm cgm viewed glucoselowering interventions rather aids assess effectiveness glucoselowering interventions prevent detect hypoglycemiatiming frequency smbg may determined individually based type diabetes type antihyperglycemic treatment prescribed need information blood glucose levels individuals capacity use information testing modify healthy behaviours selfadjust antihyperglycemic agentssmbg fgm cgm linked structured educational therapeutic program designed facilitate behaviour change improve blood glucose levels prevent hypoglycemia a1c measurement average blood glucose control last 2 3 months approximately 50 value comes last 30 daysyou a1c measured every 3 months blood glucose targets met making changes diabetes management circumstances significant changes made glucoselowering therapy pregnancy healthcare provider may check a1c frequentlychecking blood glucose glucose meter also known selfmonitoring blood glucose using flash glucose meter continuous glucose monitor willdetermine high low blood glucose given timeshow health behaviours diabetes medications affect blood glucose levelshelp diabetes healthcare team make health behaviour medication changes improve blood glucose levelsdiscuss diabetes healthcare team often check blood glucose level glycated hemoglobin a1c reliable estimate mean plasma glucose pg levels previous 8 12 weeks 1mccarter rj hempe jm chalew sa mean blood glucose biological variation greater influence hba1c levels glucose instability analysis data diabetes control complications trialdiabetes care 2006 29 352355crossref pubmed scopus 110 google scholar mean blood glucose bg level 30 days immediately preceding blood sampling days 0 30 contributes 50 result prior 90 120 days contributes 10 2goldstein de little rr lorenz ra et altests glycemia diabetesdiabetes care 2004 27 17611773crossref pubmed scopus 473 google scholar 3calisti l tognetti measure glycosylated hemoglobinacta biomed 2005 76 5962pubmed google scholar uncommon circumstances rate red blood cell turnover significantly shortened extended structure hemoglobin altered a1c may accurately reflect glycemic status table 1table 1factors affect a1cfactorincreased a1cdecreased a1cvariable change a1cerythropoiesisiron deficiencyb12 deficiencydecreased erythropoiesisuse erythropoietin iron b12reticulocytosischronic liver diseasealtered hemoglobinfetal hemoglobinhemoglobinopathiesmethemoglobingenetic determinantsaltered glycationalcoholismchronic renal failuredecreased erythrocyte phingestion aspirin vitamin c vitamin ehemoglobinopathiesincreased erythrocyte pherythrocyte destructionincreased erythrocyte lifespansplenectomydecreased erythrocyte lifespan chronic renal failure hemoglobinopathies splenomegaly rheumatoid arthritis antiretrovirals ribavirin dapsoneassayshyperbilirubinemiacarbamylated hemoglobinalcoholismlarge doses aspirinchronic opiate usehypertriglyceridemiahemoglobinopathiesa1c glycated hemoglobin open table new tab a1c glycated hemoglobin a1c preferred standard assessing glycated hemoglobin laboratories encouraged use assay methods standardized diabetes control complications trial dcct reference 4american diabetes association standards medical care diabetes2007diabetes care 2007 30 s441crossref pubmed scopus 1524 google scholar 5sacks db bruns de goldstein de et alguidelines recommendations laboratory analysis diagnosis management diabetes mellitusclin chem 2002 48 436472crossref pubmed scopus 750 google scholar 6american diabetes association european association study diabetes international federation clinical chemistry laboratory medicine international diabetes federation consensus statement worldwide standardisation hba1c measurementdiabetologia 2007 50 20422043crossref pubmed scopus 113 google scholar a1c valuable indicator treatment effectiveness measured least every 3 months glycemic targets met diabetes therapy adjusted changed testing 6month intervals may considered situations glycemic targets consistently achieved 4american diabetes association standards medical care diabetes2007diabetes care 2007 30 s441crossref pubmed scopus 1524 google scholar 7driskell oj holland waldron jl et alreduced testing frequency glycated hemoglobin hba1c associated deteriorating diabetes controldiabetes care 2014 37 27312737crossref pubmed scopus 47 google scholar circumstances significant changes made therapy pregnancy appropriate check a1c frequently see diabetes pregnancy chapter p s255 a1c may also used diagnosis diabetes adults see screening diabetes adults chapter p s16 canada a1c reported using national glycohemoglobin standardization program ngsp units 2007 consensus statement american diabetes association european association study diabetes international diabetes federation called a1c reporting worldwide change dual reporting a1c international federation clinical chemistry laboratory medicine ifcc si units mmolmol derived ngsp units hope fully converting exclusive reporting si units 8consensus committee consensus statement worldwide standardization hemoglobin a1c measurement american diabetes association european association study diabetes international federation clinical chemistry laboratory medicine international diabetes federationdiabetes care 2007 30 23992400crossref pubmed scopus 298 google scholar however adopted worldwide canada united states still use ngsp units 9sacks db measurement hemoglobin a1c new twist path harmonydiabetes care 2012 35 26742680crossref pubmed scopus 92 google scholar although advantages reporting si units notable disadvantage massive education effort would required ensure recognition adoption new units canada currently performing dual reporting therefore throughout document a1c still written ngsp units wish convert ngsp units si units following equation used ifcc 1093 ngsp 2350 10weykamp c john wg mosca et althe ifcc reference measurement system hba1c 6year progress reportclin chem 2008 54 240248crossref pubmed scopus 183 google scholar see appendix 15 glycated hemoglobin conversion chart conversion a1c ngsp units ifcc si units pointofcare a1c analyzers benchtop instruments use fingerprick capillary blood sample designed use healthcare providers office treatment room bedside blood applied test cartridge sample analyzed within several minutes 11diagnostic evidence cooperative oxford pointofcare hba1c testsdiagnosis diabetes national institue health research nhs london2016httpswwwoxforddecnihracukfilesreportsandresourceshorizonscanningreport0044pochba1cindiagnosispdfgoogle scholar pointofcare a1c testing several potential advantages laboratory a1c testing including rapid test results expedite medical decisionmaking convenience people diabetes potential improved health system efficiency improved access testing underserved populations 12spaeth ba shephard md schatz pointofcare testing haemoglobin a1c remote australian indigenous communities improves timeliness diabetes carerural remote health 2014 14 2849pubmed google scholar number pointofcare a1c devices commercially available monitoring glycemic control however united kingdom systematic review concluded evidence impact using pointofcare a1c testing medication use clinical decisionmaking participants outcomes lacking randomized trial economic evaluation needed 13hirst ja mclellan jh price cp et alperformance pointofcare hba1c test devices implications use clinical practicea systematic review metaanalysisclin chem lab med 2017 55 167180crossref pubmed scopus 64 google scholar currently pointofcare a1c analyzers approved diagnosis diabetes several studies shown a1c concentrations higher ethnic groups african asian hispanic caucasian persons similar plasma glucose 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provide feedback results healthy behaviour interventions antihyperglycemic pharmacological treatments increase ones empowerment adherence treatment also provide information person diabetes diabetes healthcare team facilitate longerterm treatment modifications titrations well shorterterm treatment decisions insulin dosing people type 1 type 2 diabetes finally situations a1c accurately reflect glycemia table 1 monitoring bg necessary adequately monitor glycemia 25malekiani cl ganesan decker cf effect hemoglobinopathies hemoglobin a1c measurementsam j med 2008 121 e5abstract full text full text pdf pubmed scopus 13 google scholar monitoring bg effective combined education program incorporates instruction people diabetes healthy behaviour changes response bg values healthcare providers adjust antihyperglycemic medications response bg readings 26parkin cg davidson ja value selfmonitoring blood glucose pattern analysis improving diabetes outcomesj diabetes sci technol 2009 3 500508crossref 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education people diabetes receive instruction perform selfmonitoring record results organized fashion meaning various bg levels behaviour actions affect bg results recommended frequency monitoring bg may individualized persons unique circumstances factors influencing recommendation include type diabetes type antihyperglycemic therapy changes antihyperglycemic therapy adequacy glycemic control literacy numeracy skills propensity hypoglycemia awareness hypoglycemia occupational requirements acute illness people type 1 diabetes monitoring bg essential achieving maintaining good glycemic control large cohort study performance 3 selftests per day associated statistically clinically significant 10 absolute reduction a1c 8consensus committee consensus statement worldwide standardization hemoglobin a1c measurement american diabetes association european association study diabetes international federation clinical chemistry laboratory medicine international diabetes federationdiabetes care 2007 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