A large multinational study including data from 52,721 participants have found international differences in prevalence of coeliac disease (CD) in those with T1D. Coeliac disease has a known association with T1D, and this study aimed to examine global differences in prevalence and management to improve understanding of the impact of both conditions.

Despite the known association, there has been a lack of international studies comparing clinical characteristics and treatment between individuals with T1D only and T1D with co-existing coeliac disease. Additionally, detection of the disease is likely to differ internationally reflecting different screening practices.

The research was an analysis from the following four large databases across three continents: the Prospective Diabetes Follow-up (DPV) registry in Germany and Austria; the National Paediatric Diabetes Audit (NPDA) in the U.K.(England and Wales); the T1D Exchange Clinic Network (T1DX) in the U.S.; and the Australasian Diabetes Data Network (ADDN). The ADDN, funded by the T1DCRN, is Australia’s first of its kind that pools clinical data from people with T1D into one centralised registry. Australian data can now be used to benchmark and compare between registries worldwide.

The main study measure was the rate of CD among participants with type 1 diabetes. Screening for CD was performed according to local practices, in keeping with the International Society for Pediatric and Adolescent Diabetes (ISPAD) guidelines which recommend screening at the time of diabetes diagnosis and every 1–2 years thereafter.  CD was defined based on biopsy-proven results. “Suspected CD” was defined as a positive CD screening result without small bowel biopsy.

They found that individual biopsy-confirmed CD was present in 1,835 youths (3.5%) and was diagnosed at a median age of 8.1 years. Diabetes duration at CD diagnosis was <1 year in 37% of youths, >1–2 years in 18% of youths, >3–5 years in 23% of youths, and >5 years in 17% of youths. Coeliac disease was diagnosed before T1D in 5.4% of youths.

CD prevalence ranged from 1.9% in the T1DX to 7.7% in the ADDN and was higher in girls than boys (4.3% vs. 2.7%, P < 0.001). Children with coexisting CD were younger at diabetes diagnosis compared with those with type 1 diabetes only (5.4 vs. 7.0 years of age, P < 0.001) and fewer were non-white (15 vs. 18%, P < 0.001).

Height standard deviation score (SDS) was lower in those with CD (0.36 vs. 0.48, adjusted P < 0.001) and fewer were overweight/obese (34 vs. 37%, adjusted P < 0.001), whereas mean HbA1c values were comparable: 8.3% (67mmol/mol) versus 8.4% (68 mmol/mol).

These differences in CD prevalence, highest being in Australia, may reflect international variation in screening and diagnostic practices and/ or CD risk. The gold standard of diagnosis in Australia is a small bowel biopsy. The requirement of the small bowel biopsy varies internationally.  In Australia, coeliac disease screening is recommended in the ADS/APEG National Evidence-Based Clinical Care Guidelines for Type 1 diabetes in Children, Adolescents and Adults.

The lower height-SDS supports close monitoring of growth and nutrition in people with T1D and CD. Since dietary adherence was not documented in the four registries, it is possible that the lower height SDS may reflect a subgroup of patients who did not adhere to the gluten-free diet. Alternatively, there may be a subgroup of patients who have not achieved catch-up growth after the diagnosis of CD. Regardless, the findings emphasise the importance of monitoring growth and nutrition in this population.

To find out more about ADDN, head to their website.

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