Does autoimmune thyroiditis affect the clinical course of type 1 diabetes mellitus in children, regardless of the functional state of the thyroid gland?

Background. The combination of type 1 diabetes mellitus (DM1) and autoimmune thyroiditis (AIT) is quite common and varies in frequency from 20 to 35% among DM1 children. The literature data indicate a negative effect of the combination of these diseases on the control of DM1, frequent hypoglycemia, and a deterioration of the lipid profile in children with hypothyroidism in the AIT outcome. Objective. Evaluation of the effect of AIT on the compensation of carbohydrate metabolism and the development of microvascular complications in DM1 children regardless of the functional state of the thyroid gland. Methods. A cross-sectional study with analysis of medical records of children undergoing inpatient treatment at the Regional Endocrinology Center of the Regional Children’s Clinical Hospital with a diagnosis of autoimmune polyglandular syndrome type 3 (APS 3: DM1 + AIT) were conducted. Data on the date of manifestation and the duration of the disease, the revealed complications, the glycated hemoglobin (HbA1c), TSH, cT4, anti-thyroid peroxidase antibody (anti-TPO) levels and the results of ultrasound, as well as the presence of chronic complications (diabetic retino-, nephro-, polylineuro- and chiropathy) were recorded. The distribution into subgroups was carried out according to the TSH level: euthyroidism (ET): 0.4-5.0 цЮ/L; subcompensated hypothyroidism (SCHT): 5.0-10.0 цЮ/L; drug-compensated hypothyroidism (DCHT): 0.4-5.0 цЮ/L on sodium levothyroxine; and analysis of AIT catamnesis. Results. The main group included 112 children diagnosed with APS 3. According to the functional state of the thyroid gland, ET was observed in 38.4% of cases (n=43), SCHT - in 42% (n=47), DCHT - in 19.6% (n=22). In general, in children with APS 3, regardless of the thyroid function in the outcome of AIT, the HbA1c level was significantly higher compared to the control group (n=77; 9.8 versus 8.7%; p=0.001), including with ET - 9.7%, with SCHT - 9.5%, and with the greatest differences with DCHT - 10.3%. The frequency of diabetes complications in the groups did not differ, but in the main group, diabetic nephropathy was significantly more often diagnosed, as well as the presence of several complications at once. The highest complication rate was found in the DCHT group - 68.2% (n=15), in the subgroups of children with ET and SCHT - 39.5% (n=17) and 46.8% (n=22), respectively. Children with DCHT had a higher incidence of nephropathy. Hyropathy was rare in both groups, however, was observed 6 times more often in the group with combination of DM1 and AIT. Conclusion. Children with a combination of DM1 and AITare at high risk for decompensation of carbohydrate metabolism and the development of chronic DM1 complications regardless of the functional state of the thyroid gland. Selective screening for AIT (TSH, anti-TPO and thyroid ultrasound) in DM1 children is necessary already at the stage of diabetes manifestation. Further dynamic monitoring of children with APS 3, regardless of the initial functional state of the thyroid gland, should be carried out taking into account the established risks, more carefully, with annual monitoring of TSH level and screening for chronic complications.

autoimmune thyroiditis, type 1 diabetes mellitus, autoimmune polyglandular syndrome type 3, children