How does autoimmune thyroiditis in children with type 1 diabetes mellitus influence glycemic control, lipid profile and thyroid volume?

Aim: To investigate whether autoimmune thyroiditis (AIT) in children with type 1 diabetes mellitus (DM1) has any influence on glycemic control, lipid profile or thyroid volume. Methods: A total of 330 patients with DM1 and AIT (DM1+AIT group) were compared with 309 children with DM1 without AIT (control group). Patients were treated in four Polish academic pediatric diabetes centers from 2008 to 2012: Warsaw, Lodz, Katowice and Gdansk. All patients underwent measurements of thyroid-stimulating hormone (TSH), free thyroxine, anti-thyroid peroxidase (anti-TPO) antibody, anti-thyroglobulin (anti-TG) antibody and HbA(1c) levels, and thyroid ultrasound examination. Results: Among AIT+DM1 patients, 62% (n=205) were female, whereas in the control group 60.8% (n=188) were male (p<0.0001). Children with AIT+DM1 had lower a BMI-SDS (mean difference of -0.5, 95% CI -0.68 to -0.33; p<0.0001), had a higher SDSthyroid volume (0.27, 95% CI 0.03-0.51; p=0.014) and needed less insulin (-0.15, 95% CI -0.20 to -0.11 U/kg body weight per day; p<0.0001) in comparison with the control group. AIT patients had higher HbA(1c) levels (0.66, 95% CI 0.36%-0.96%, p<0.0001), lower HDL-cholesterol levels (-3.68, 95% CI -1.41 to -5.94 mg/dL, p=0.002) and higher triglyceride levels (7.16, 95% CI 1.22-13.10 mg/dL, p=0.02). Patients with positive anti-TPO and anti-TG antibodies were older (by 1.95 years, 95% CI 0.98-2.92 years, p =0.006)and had longer DM1 duration (by 1.64 years, 95% CI 0.76-2.52 years, p=0.006). Presence of anti-TPO antibodies was associated with higher TSH levels (odds ratio 2.34, 95% CI 1.36-4.04; p=0.007). Conclusion: AIT accompanying DM1 is associated with worse glycemic control and lipid profile as well as a lower daily insulin requirement. The female gender is more likely to develop AIT and hypothyroidism.