We assessed the associations between A1C and in-hospital mortality using data from a nationwide sample of AMI patients who had both prior diabetes and measurement of A1C (N = 15,337).
When evaluated continuously, we observed no evidence of a J-shaped relation between A1C and in-hospital mortality in multivariable analysis (test for linearity P = .89). Patients with lowest (<5.5 % ) and highest A1C (≥9.5 % ) had a crude mortality rate of 4.6 % and 2.8 % , respectively, compared with 3.8 % among those in the referent A1C category (6.5 % to <7 % ). In multivariable regression, we observed no association between low A1C (<5.5 % , odds ratio 0.81, 95 % CI 0.47-1.39) or high A1C (A1C ≥9.5, odds ratio 1.31, 95 % CI 0.94-1.83) and mortality as compared with the referent group. These findings can only be generalized to the subset of patients with diabetes who had A1C assessed during their hospitalization; these patients tended to be healthier than those in whom A1C was not assessed.
In this large contemporary cohort of patients with diabetes presenting with AMI, we did not observe a J-shaped association between A1C and mortality.