The prevalence of autoimmune diseases in antibody negative type 1 diabetes mellitus

Objectives Type 1 diabetes mellitus (T1D) results from autoimmune destruction of pancreatic β cells. T1D individuals face increased risk of autoimmune thyroid disease (AITD) and celiac disease (CD). While most patients present with β-cell autoantibodies, 5–10 % do not and are classified as antibody-negative T1D (AB− T1D). Whether autoimmune disease risk differs between AB− and antibody-positive T1D (AB+ T1D) remains uncertain. Methods Children aged 6 months to 18 years diagnosed with T1D between January 2010 and June 2023 were reviewed and categorized as AB+ or AB− based on islet cell antigen, insulin, and GAD-65 autoantibodies at diagnosis. Each AB− patient was matched with two age- and sex-matched AB+ controls within the diagnosis date. Chi-square testing compared CD and AITD prevalence between groups, with significance set p<0.05. Results The study included 149 AB− and 298 AB+ subjects. CD prevalence was 5.0 % in the AB+ group and 3.4 % in the AB− group. AITD prevalence was 4.4 % in the AB+ group and 2.7 % in the AB− group. No significant differences were identified. A combined diagnosis of CD and AITD occurred only in the AB+ group (2.2 %, p=0.024). At diagnosis, AB+ patients had higher glucose and beta-hydroxybutyrate levels and lower C-peptide, while venous pH was similar. Conclusions AITD and CD prevalence did not differ significantly between AB− and AB+ children with T1D, though coexistence of both conditions occurred only in AB+ patients. These findings suggest that AB− T1D may still involve autoimmunity and support similar surveillance strategies for autoimmune diseases in both groups.