BACKGROUND

Poor glycemic control is associated with increased risk of cardiovascular disease (CVD) in type 1 diabetes mellitus (T1DM); however, little is known about mechanisms specific to T1DM. In T1DM, myocardial injury can induce persistent cardiac autoimmunity. Chronic hyperglycemia causes myocardial injury, raising the possibility that hyperglycemia-induced cardiac autoimmunity could contribute to long-term CVD complications in T1DM.

METHODS

We measured the prevalence and profiles of cardiac autoantibodies (AAbs) in longitudinal samples from the DCCT (Diabetes Control and Complications Trial) in participants with mean hemoglobin A (HbA) ≥9.0% (n=83) and ≤7.0% (n=83) during DCCT. We assessed subsequent coronary artery calcification (measured once during years 7-9 in the post-DCCT EDIC [Epidemiology of Diabetes Interventions and Complications] observational study), high-sensitivity C-reactive protein (measured during EDIC years 4-6), and CVD events (defined as nonfatal myocardial infarction, stroke, death resulting from CVD, heart failure, or coronary artery bypass graft) over a 26-year median follow-up. Cardiac AAbs were also measured in matched patients with type 2 diabetes mellitus with HbA ≥9.0% (n=70) and ≤7.0% (n=140) and, as a control for cardiac autoimmunity, patients with Chagas cardiomyopathy (n=51).

RESULTS

Apart from HbA levels, the DCCT groups shared similar CVD risk factors at the beginning and end of DCCT. The DCCT HbA ≥9.0% group showed markedly higher cardiac AAb levels than the HbA ≤7.0% group during DCCT, with a progressive increase and decrease in AAb levels over time in the 2 groups, respectively ( P<0.001). In the HbA ≥9.0% group, 46%, 22%, and 11% tested positive for ≥1, ≥2, and ≥3 different cardiac AAb types, respectively, similar to patients with Chagas cardiomyopathy, compared with 2%, 1%, and 0% in the HbA ≤7.0% group. Glycemic control was not associated with AAb prevalence in type 2 diabetes mellitus. Positivity for ≥2 AAbs during DCCT was associated with increased risk of CVD events (4 of 6; hazard ratio, 16.1; 95% CI, 3.0-88.2) and, in multivariable analyses, with detectable coronary artery calcification (13 of 31; odds ratio, 60.1; 95% CI, 8.4-410.0). Patients with ≥2 AAbs subsequently also showed elevated high-sensitivity C-reactive protein levels (6.0 mg/L versus 1.4 mg/L in patients with ≤1 AAbs; P=0.003).

CONCLUSIONS

Poor glycemic control is associated with cardiac autoimmunity in T1DM. Furthermore, cardiac AAb positivity is associated with an increased risk of CVD decades later, suggesting a role for autoimmune mechanisms in the development of CVD in T1DM, possibly through inflammatory pathways.