- More than a fifth of the Finnish population with type 1 diabetes (T1D) has another autoimmune disease (AD), most commonly hypothyroidism, celiac disease, and hyperthyroidism.
- People with T1D should be screened for ADs throughout life.
Why this matters
- Most studies have been in young individuals with short-term T1D, but ADs often arise later in life.
- Study included 4758 individuals with T1D from the Finnish Diabetic Nephropathy (FinnDiane) Study, with data linked to nationwide health registries, 1970-2015.
- Funding: Folkhälsan Research Foundation; Academy of Finland; Novo Nordisk Foundation; Finnish Diabetes Research Foundation; others.
- An additional 1245 ADs were identified in 1087 individuals with T1D, including:
- Hypothyroidism in 18.1%;
- Celiac disease in 4.4%;
- Hyperthyroidism in 2.4%;
- Atrophic gastritis in 1.0%; and
- Addison's disease in 0.4%.
- Overall, 22.8% with T1D had ≥1 additional AD: 31.6% women and 14.9% men (P<.0001>
- Females significantly outnumbered men for all ADs except atrophic gastritis.
- Hypothyroidism risk increased 1.7% (P<.0001 by each increasing year of age at t1d onset.>
- Celiac disease risk increased by 1.5% for each decreasing year of age at T1D onset (P=.048).
- Age at onset not known for all ADs.
- Potential ADs underestimated because of deaths.