Changes in glycaemic control and risk of coronary artery disease in type 1 diabetes mellitus: findings from the Pittsburgh Epidemiology of Diabetes Complications Study (EDC)

Aims/hypothesis To complete a comparative analysis of studies that have examined the relationship between glycaemia and cardiovascular disease (CVD)/coronary artery disease (CAD) and perform a prospective analysis of the effect of change in glycosylated Hb level on CAD risk in the Pittsburgh Epidemiology of Diabetes Complications Study (EDC) of childhood-onset type 1 diabetes mellitus (n = 469) over 16 years of two yearly follow-up. Methods Measured values for HbA₁ and HbA₁c from the EDC were converted to the DCCT-standard HbA₁c for change analyses and the change in HbA₁c was calculated (final HbA₁c minus baseline HbA₁c). CAD was defined as EDC-diagnosed angina, myocardial infarction, ischaemia, revascularisation or fatal CAD after medical record review. Results The comparative analysis suggested that glycaemia may have a stronger effect on CAD in patients without, than in those with, albuminuria. In EDC, the change in HbA₁c differed significantly between CAD cases (+0.62 ± 1.8%) and non-cases (-0.09 ± 1.9%) and was an independent predictor of CAD. Conclusions/interpretation Discrepant study results regarding the relationship of glycaemia with CVD/CAD may, in part, be related to the prevalence of renal disease. Measures of HbA₁c change over time show a stronger association with CAD than baseline values.