Association of Longitudinal Values of Glycated Hemoglobin With Cardiovascular Events in Patients With Type 2 Diabetes and Multivessel Coronary Artery Disease

IMPORTANCE: Glycated hemoglobin (HbA(1c)) values are used to guide glycemic control, but in patients with type 2 diabetes and multivessel coronary artery disease (CAD), the association of the longitudinal values of HbA(1c) with cardiovascular outcomes is unclear. OBJECTIVE: To assess whether longitudinal variation of HbA(1c) is associated with cardiovascular events in long-term follow-up among patients with diabetes and multivessel CAD. DESIGN, SETTING, AND PARTICIPANTS: This cohort study included 888 patients with type 2 diabetes and multivessel CAD in the Medicine, Angioplasty, or Surgery Study (MASS) Registry of the Heart Institute of the University of São Paulo from January 2003 to December 2007. Data were analyzed from January 15, 2018, to October 15, 2019. EXPOSURE: Longitudinal HbA(1c) values. MAIN OUTCOMES AND MEASURES: The combined outcome of all-cause mortality, myocardial infarction, and ischemic stroke. RESULTS: Of 888 patients with type 2 diabetes and multivessel CAD, 725 (81.6%; median [range] age, 62.4 [55.7-68.0] years; 467 [64.4%] men) had complete clinical and HbA(1c) information during a median (interquartile range) follow-up period of 10.0 (8.0-12.3) years, with a mean (SD) of 9.5 (3.8) HbA(1c) values for each patient. The composite end point of death, myocardial infarction, or ischemic stroke occurred in 262 patients (36.1%). A 1-point increase in the longitudinal value of HbA(1c) was significantly associated with a 14% higher risk of the combined end point of all-cause mortality, myocardial infarction, and ischemic stroke (hazard ratio, 1.14; 95% CI, 1.04-1.24; P = .002) in the unadjusted analysis. After adjusting for baseline factors (ie, age, sex, 2-vessel or 3-vessel CAD, initial CAD treatments, ejection fraction, and creatinine and low-density lipoprotein cholesterol levels), a 1-point increase in the longitudinal value of HbA(1c) was associated with a 22% higher risk of the combined end point (hazard ratio, 1.22; 95% CI, 1.12-1.35; P < .001). CONCLUSIONS AND RELEVANCE: Longitudinal increase of HbA(1c) was independently associated with higher rates of cardiovascular events in patients with type 2 diabetes and multivessel CAD.