Autoimmune diseases and the risk and prognosis of latent autoimmune diabetes in adults.

Aims/hypothesis: The aim of this study was to clarify the impact of autoimmune disease (AD) comorbidity on the risk and prognosis of latent autoimmune diabetes in adults (LADA).

Methods: We used data from a Swedish study comprising newly diagnosed cases of LADA (n=586, stratified into LADA and LADA by autoantibody levels), type 2 diabetes (n=2003) and matched control participants (n=2355). Information on 33 ADs and diabetic retinopathy was obtained by linkage to regional and national registers. We estimated the ORs for LADA and type 2 diabetes in relation to ADs before diabetes diagnosis, and the HRs for diabetic retinopathy after diabetes diagnosis. We performed functional pathway analyses to explore biological mechanisms driving the associations.

Results: Individuals with ADs exhibit an increased susceptibility to LADA (OR 1.70; 95% CI 1.36, 2.13), particularly those with thyroid dysfunction (OR 1.88; 95% CI 1.38, 2.56), inflammatory bowel disease (OR 1.78; 95% CI 1.00, 3.16) or vitiligo (OR 3.91; 95% CI 1.93, 7.94), with stronger associations being observed for the LADA phenotype. Only psoriasis was linked to type 2 diabetes (OR 1.47; 95% CI 1.08, 1.99). The biological pathways shared by LADA and ADs revolved around immune responses, including innate and adaptive immune pathways. The HRs for diabetic retinopathy in LADA patients with and without AD vs those with type 2 diabetes were 2.11 (95% CI 1.34, 3.32) and 1.68 (95% CI 1.15, 2.45), respectively.

Conclusions/interpretation: We confirm that several common ADs confer an excess risk of LADA, especially LADA with higher GADA levels, but having such a comorbidity does not appear to affect the risk of diabetic retinopathy.