Endocrine Abstracts

Introduction: Type 1 diabetes (T1DM) is often associated with autoimmune thyroid disease (AITD). Common susceptibility genes increase risk for development of both AITD and T1DM. The influence of this comorbidity on the risk of diabetic microangiopathy is unknown.

Methods/design: We included 100 consecutive patients with T1DM (55 men, and 45 women) aged 29 (mean, S.D.=6) with diabetes duration 13 (6) years, 35 had diagnosed at least one microangiopathic complication (retinopathy or nephropathy or neuropathy).

Exclusion criteria were: history of thyroid disease, current treatment of L-thyroxin or anti-thyroid drugs.

Anti-thyroid peroxidase (aTPO) and anti-thyroglobulin (aTg) antibodies, anti- TSH receptor antibodies (TRAb) were determined using a luminescence method. Assays for TSH and free thyroid hormones (triiodothyronine, fT₃, and thyroxin, fT₄), as well as thyroid ultrasonography (USG) were also performed. In statistical analysis Fisher exact test and multivariate logistic regression were used.

Results: The prevalence of thyroid autoimmunity (positivity for aTPO or aTg) in the study group was 31% (19 women, and 12 men). 8% of patients were only positive for ATPO and 5% only for ATg, no patients were positive for TRAb. Subclinical hypothyroidism was diagnosed in 9%, and overt hypothyroidism in 2% of patients. Among patients with anti-thyroid autoimmunity prevalence of microangiopathy was lower than in patients without positive titre of aTPO and aTg: 3 of 31 (10%) vs 32 of 69 (46%), P=0.0003. In multivariate logistic regression model presence of anti-thyroid antibodies was associated with lower odds of microangiopathy independently of sex, age, BMI, cigarette smoking, systolic blood pressure, HbA1c value, serum TSH and LDL-cholesterol concentrations (OR 18.3, 95% CI: 3.7–89.6, P=0.0003).

Conclusion: Thyroid autoimmunity was associated with lower rate of microangiopathic complications in patients with T1DM. Prospective studies are needed to determine the causality of this finding.