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.
For their population-based cohort study, Dr. Kurien and colleagues analyzed data from Swedish National Patient Register between 1964 and 2009.
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.