Association between glycated haemoglobin levels and cardiovascular outcomes in patients with type 2 diabetes and cardiovascular disease: a secondary analysis of theTECOSrandomized clinical trial

Aims Whether glycaemic control is associated with cardiovascular outcomes in patients with type 2 diabetes (T2D) is unclear. Consequently, we assessed the relationship between glycated haemoglobin (HbA(1c)) and cardiovascular outcomes in a placebo-controlled randomized trial which demonstrated no cardiovascular effect of sitagliptin in patients with T2D and atherosclerotic vascular disease. Methods and results Secondary analysis of 14 656 TECOS participants with time to event analyses using multivariable Cox proportional hazard models. During a median 3.0 (interquartile range 2.3-3.8) year follow-up, 456 (3.1% of 14 656) patients had first hospitalization for heart failure (HF), 1084 (11.5%) died, 1406 (9.6%) died or were hospitalized for HF, and 1689 (11.5%) had a non-HF cardiovascular event (cardiovascular death, non-fatal stroke, non-fatal myocardial infarction, or hospitalization for unstable angina). Associations between baseline or time-varying HbA(1c)and cardiovascular outcomes were U-shaped, with the lowest risk when HbA(1c)was around 7%. Each one-unit increase in the time-varying HbA(1c)above 7% was associated with an adjusted hazard ratio (HR) of 1.21 [95% confidence interval (CI) 1.11-1.33] for first HF hospitalization, 1.11 (1.03-1.21) for all-cause death, 1.18 (1.09-1.26) for death or HF hospitalization, and 1.10 (1.02-1.17) for non-HF cardiovascular events. Each one-unit decrease in the time-varying HbA(1c)below 7% was associated with an adjusted HR of 1.35 (95% CI 1.12-1.64) for first HF hospitalization, 1.37 (1.16-1.61) for death, 1.42 (1.23-1.64) for death or HF hospitalization, and 1.22 (1.06-1.41) for non-HF cardiovascular events. Conclusion Glycated haemogobin exhibits a U-shaped association with cardiovascular outcomes in patients with T2D and atherosclerotic vascular disease, with nadir around 7%. Clinical Trial Registration: ClinicalTrials.gov Identifier: NCT00790205.