Does autoimmune hypothyroidism increase the risk of neurovascular complications in type 1 diabetes?

Type 1 diabetes (T1DM) often coexists with other autoimmune diseases, most commonly with hypothyroidism. To date, the influence of coexisting autoimmune hypothyroidism (AHT) on the course of chronic neurovascular complications of autoimmune diabetes has not been established. The aim of the study was to assess the relationship between AHT and the occurrence of chronic T1DM complications.

The study group comprised 332 European Caucasian participants with T1DM [165 (49.7%) men]. AHT was recognized in subclinical and overt hypothyroidism and confirmed by the presence of anti-thyroid autoantibodies: anti-peroxidase (ATPO) and/or anti-thyroglobulin (ATg) and ultrasonography (hypoechogenicity, parenchymal heterogeneity, lymph nodes assessment).

In the analyzed group, 48.5% of patients were diagnosed with at least one neurovascular complication. At the time of enrollment, 16.3% of participants were diagnosed with AHT. Patients with AHT, compared to those without AHT, were characterized by a higher prevalence of neurovascular complications (64.8 vs. 45.3%; P = 0.009) and retinopathy (55.6 vs. 38.9%; P = 0.02). There were significant differences between groups with and without neurovascular complications, with regard to classic risk factors for chronic diabetes complications: age, T1DM duration, SBP, DBP, HbA_1c, TG, eGFR and hypertension prevalence. In the multivariate logistic regression analysis, AHT was an independent predictor of neurovascular complications after adjusting for age, DBP, HbA_1c and TG (odds ratio, 2.40; 95% confidence interval, 1.17-4.92; P = 0.02).

AHT coexisting with T1DM was associated with a higher incidence of neurovascular complications.