By Will Boggs, MD

NEW YORK (Reuters Health) – Longstanding celiac disease is associated with an increased risk of diabetic retinopathy in patients with type 1 diabetes, a new study finds.

The prevalence of celiac disease in type 1 diabetes ranges from 3% to 12%, and the link between the two diseases is well established. “In fact, this type of screening is already adopted in many countries, including Sweden,” Dr. Kaziwe Mollazadegan from Karolinska Institutet in Stockholm told Reuters Health by email.

Dr. Mollazadegan and colleagues used data from the Swedish National Patient Register to examine the risk of diabetic retinopathy (DRP) in patients with type 1 diabetes and biopsy-proven celiac disease compared with patients with only type 1 diabetes.

This study, published online September 10 in Diabetes Care, included 40,619 patients with type 1 diabetes alone and 947 patients with type 1 diabetes and celiac disease.

During the first five years after celiac disease diagnosis, the risk of DRP was lower than in patients with type 1 diabetes alone. The risk of DRP was similar for the two groups during years 5 to 10. And from year 10, the risk of DRP was substantially higher for the group with celiac disease than for the group without celiac disease (10-15 years: adjusted hazard ratio, 2.83; >=15 years: aHR, 3.01).

After more than 15 years of follow-up, the absolute risk of DRP was 2.8 per 100 person-years in patients with type 1 diabetes and celiac disease, compared with 1.8 per 100 person-years in patients with type 1 diabetes alone.

The risk was increased regardless of sex, age, or calendar period at type 1 diagnosis, and the increased risk showed a similar pattern when the outcome was restricted to severe DRP.

“More research is needed in order to clarify this matter,” Dr. Mollazadegan said. “Hopefully, our findings may influence other researchers to examine this association in more detail.”

“Celiac disease is a complex disease and we still have a lot to learn from this condition,” Dr. Mollazadegan added. “I would also like to point out that in patients with type 1 diabetes and positive celiac disease serology, it is important to confirm a celiac diagnosis through biopsy to avoid a false-positive celiac diagnosis.”

Diabetes Care 2012.