Celiac.com 01/08/2016 - Adults with both celiac disease and type 1 diabetes face an increased risk of developing thyroid disease, according to a new study.
The study was done by researchers Matthew Kurien, Kaziwe Mollazadegan, David S. Sanders and Jonas F. Ludvigsson. They are variously affiliated with the Department of Gastroenterology, Royal Hallamshire Hospital, Sheffield, U.K., the Academic Unit of Gastroenterology at the University of Sheffield in Sheffield, U.K., the Department of Medical Epidemiology and Biostatistics at Karolinska Institutet in Stockholm, Sweden, and the Department of Pediatrics of Örebro University Hospital at Örebro University in Örebro, Sweden.
Their team identified all 42,539 patients diagnosed with type 1 diabetes before age 31 years of age. They used small intestinal biopsy reports showing villous atrophy to identify 947 type 1 diabetes patients with celiac disease between 1969 and 2008 (55.1% women; mean age of celiac disease diagnosis, 12 years).
The research team then selected up to five type 1 diabetes patients as controls for each patient with both type 1 diabetes and celiac disease, and matched them for age, sex and birth year. They selected 4,584 in all; 54.5% women. They then used Cox regression analysis to calculate hazard ratios for future thyroid disease, with celiac disease as a time-dependent variable.
They found that, over an average 13 years of follow-up, 90 patients in the group with both type 1 diabetes and celiac disease developed autoimmune thyroid disease (either hypothyroid or hyperthyroid); with an average age at thyroid disease diagnosis of 25 years old.
In total, nearly 11% of patients in the type 1 diabetes and celiac disease group were diagnosed with thyroid disease at some stage of life vs. 7.2% of patients with type 1 diabetes without celiac disease.
Patients with both type 1 diabetes and celiac disease faced an increased risk for hypothyreosis (HR = 1.66; 95% CI, 1.3-2.12) and hyperthyreosis (HR = 1.71; 95% CI, 0.95-3.11). The RR for thyroid disease in patients with both type 1 diabetes and celiac disease was 1.67 (95% CI, 1.32-2.11).
The team found the highest risk levels for thyroid disease in patients from 1964-1975, which they attributed to poor screening for thyroid disease in type 1 diabetes patients during that time.
The researchers noted that the highest risks in patients with more than ten years of celiac disease, which suggests that long-term double autoimmunity is a risk factor for autoimmune thyroid disease.