title: The association between different A1C-based measures of glycemia and risk of cardiovascular disease hospitalization.
abstract: OBJECTIVE We tested whether average monthly glycemic burden (AMGB), a marker of hyperglycemia that is a function of the extent and duration that A1C exceeded 7%, indicated greater risk of cardiovascular disease (CVD) than traditional A1C measures. RESEARCH DESIGN AND METHODS Using a case-control design, we studied 2,456 members of Kaiser Permanente Northwest with type 2 diabetes: 1,228 who experienced a CVD hospitalization, matched on age, sex, and duration of diabetes to 1,228 patients who were not hospitalized for CVD. We calculated AMGB from diabetes diagnosis until CVD hospitalization as a function of the difference between each actual or interpolated A1C measurement and 7%, resulting in an area under the curve estimate of hyperglycemic exposure, adjusted for number of months of observation. We used conditional logistic regression to compare the association between several A1C-based measures of glycemia and CVD, controlling for clinical characteristics and comorbidities. RESULTS AMGB was associated with increased CVD risk of 29% (odds ratio 1.29 [95% CI 1.16-1.44]; P < 0.001), while mean A1C was associated with a 22% risk increase (1.22 [1.09-1.37]; P < 0.001). A1C ever exceeding 7% was associated with increased CVD risk of 39% (1.39 [1.08-1.79]; P = 0.010). No model with a glycemia measure provided substantially more information than an identical model without a glycemia measure. CONCLUSIONS AMGB demonstrated somewhat greater CVD risk than mean A1C, but its clinical usefulness may be limited. A1C ever rising above 7% (53 mmol/mol) was a simple predictor of CVD risk that may have important clinical ramifications for newly diagnosed patients.
authors.affiliation: Corresponding author: Gregory A. Nichols, greg.nichols@kpchr.org.
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Nichols
authors.forename: A Gabriela
authors.initials: AG
authors.lastname: Rosales
authors.forename: Nancy A
authors.initials: NA
authors.lastname: Perrin
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Fortmann
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000378:metabolism*; D002318:Cardiovascular Diseases / Q000453:epidemiology*; D016022:Case-Control Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000150:complications*; D005260:Female; D006442:Glycated Hemoglobin / Q000378:metabolism*; D006760:Hospitalization; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012737:Sex Factors; D013997:Time Factors
chemical_list: D015415:Biomarkers; D001786:Blood Glucose; D006442:Glycated Hemoglobin