Hyperthyroidism in 276 children and adolescents with type 1 diabetes from Germany and Austria

Background/Aims: Little is known about the incidence and clinical consequences of hyperthyroidism in pediatric patients with type 1 diabetes mellitus (T1DM). Methods: We analyzed the DPV database (Diabetes Prospective Follow-Up Registry) to investigate the rate of hyperthyroidism in pediatric T1DM patients, its impact on metabolic control, and potential associations with organ-specific autoantibodies. Results: Hyperthyroidism was found in 276/60,456 patients (0.46%) and was associated with younger age, shorter diabetes duration, female sex, and reduced body mass index. Diabetic ketoacidosis (DKA) and hypoglycemia were more frequent in T1DM with comorbid hyperthyroidism, while long-term metabolic control (HbA1c) was similar in both groups. Absolute blood pressure and arterial hypertension rate were elevated in the hyperthyroid patients. Rates of microalbuminuria and diabetic retinopathy were not different. Thyroid-specific antibodies (thyroid peroxidase, thyroglobulin, thyroid receptor) were associated with hyperthyroidism. Thyroid volume and rates of cysts and nodules were higher, and echogenicity was decreased. Conclusion: Prevalence of hyperthyroidism is low in diabetic children with T1DM but increased compared to children <18 years without diabetes. Hyperthyroidism is primarily associated with acute diabetes complications (DKA and hypoglycemia) and affects blood pressure regulation. Long-term metabolic control or insulin requirement were not different.