title: Prognostic importance of baseline and serial glycated hemoglobin levels in high-risk patients with type 2 diabetes: the Rio de Janeiro Type 2 Diabetes Cohort Study.
abstract: The prognostic importance of baseline and serial glycated hemoglobin (HbA1c) changes for cardiovascular outcomes is still debated. We aimed to evaluate it in 620 high-risk individuals with type 2 diabetes (mean age 60.4 years, 37 % males, 55 % Caucasians). Patients had HbA1c levels measured at study entry and serially during follow-up. Primary end points were total cardiovascular events (CVEs), major CVEs (non-fatal myocardial infarctions and strokes plus cardiovascular deaths) and all-cause mortality. Cardiovascular and non-cardiovascular mortalities were secondary end points. HbA1c was evaluated either as a continuous variable and categorized at clinically relevant cutoffs. Multivariate Cox regressions assessed the associations with end points. After a median follow-up of 6.6 years, 125 total CVEs occurred (90 major CVEs), and 111 patients died (64 from cardiovascular diseases). After statistical adjustments for other cardiovascular risk factors, baseline and mean first-year HbA1c predicted all end points, except non-cardiovascular deaths; and hazard ratios tended to be higher for mean first year than for baseline HbA1c. Each 1 % (10.9 mmol/mol) increase in mean first-year HbA1c increased 27 % the risk of major CVEs occurrence (95 % CI 11-45 %). Updating HbA1c for values obtained beyond the second year of follow-up did not improve its predictive performance. The cardiovascular protection was observed until HbA1c values lower than 6.5 % (48 mmol/mol). Moreover, the magnitude of HbA1c reduction during the first year of follow-up was predictive of better cardiovascular outcomes, independent of baseline HbA1c levels. In conclusion, better glycemic control, especially during the first year of follow-up, is determinant of better cardiovascular outcomes in high-risk patients with type 2 diabetes, without any detectable lower threshold level of HbA1c.
authors.affiliation: Department of Internal Medicine, University Hospital Clementino Fraga Filho, School of Medicine, Universidade Federal do Rio de Janeiro, Rua Croton 72 Jacarepagua, Rio de Janeiro, RJ, CEP: 22750-240, Brazil.
authors.forename: Claudia R L
authors.initials: CR
authors.lastname: Cardoso
authors.forename: Nathalie C
authors.initials: NC
authors.lastname: Leite
authors.forename: Marcel T
authors.initials: MT
authors.lastname: Ferreira
authors.forename: Gil F
authors.initials: GF
authors.lastname: Salles
mesh_terms: D000368:Aged; D002318:Cardiovascular Diseases / Q000097:blood* / Q000175:diagnosis / Q000209:etiology / Q000401:mortality; D015331:Cohort Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000150:complications*; D005260:Female; D005500:Follow-Up Studies; D006442:Glycated Hemoglobin / Q000032:analysis* / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012307:Risk Factors; D013534:Survival
chemical_list: D006442:Glycated Hemoglobin