Effects of a Gluten-Free Diet in Patients With Type 1 Diabetes and Asymptomatic Celiac Disease

little girl with diabetes at doctor
In individuals with type 1 diabetes who test positive for asymptomatic celiac disease, a gluten-free diet may increase postprandial glycemic levels.

Among individuals with type 1 diabetes (T1D), adults are more likely to test positive for asymptomatic celiac disease (CD) than children and a gluten-free diet may increase postprandial glycemic levels, according to study results published in Diabetes Care.

Individuals with T1D are at increased risk for CD but many individuals go undiagnosed, as CD frequently presents without symptoms. The effects of a gluten-free diet in individuals with T1D and asymptomatic CD has not yet been determined.

To examine this, 2387 individuals with T1D aged 8 to 45 years (45.6% aged ≤18 years) were screened for asymptomatic CD. A total of 51 individuals who were found to have asymptomatic CD were randomly assigned to either a gluten-free or gluten-containing diet for 1 year. Asymptomatic CD was defined as having a tissue transglutaminase immunoglobulin A (TTG-IgA) level ≥30 CU and was further confirmed by a gastroenterologic biopsy with a Marsh score of ≥2. Dietary adherence was evaluated through TTG-IgA testing and quantification of dietary gluten intake every 3 months. Hemoglobin A1c (HbA1c) was measured at baseline and every 6 months during the dietary study, and all participants used continuous glucose monitoring during the study period.

Individuals aged ≤18 years were significantly more likely to have previously been screened for CD (P <.0001). Individuals aged >18 years had higher CD-seropositivity rates than younger patients (6.8% vs 4.7%; P =.035). A significant increase in HbA1c was observed in the gluten-free diet group at 12 months (+0.30%; 95% CI, 0.40-0.57; P =.028) compared with baseline, although no significant difference in HbA1c change was observed between groups. There were also no changes in the percentage of time spent in hypoglycemic, euglycemic, or hyperglycemic ranges observed over the 12-month period, but in the gluten-free diet group, postprandial glycemia was higher at both the 2-hour (+1.6 mmol/L; 95% CI, 0.7-2.6; P =.0015) and 4-hour (+1.5 mmol/L; 95% CI, 0.4-2.7; P =.0014) time points relative to premeal levels, whereas glucose levels did not significantly change and returned to premeal levels at the 4-hour time point in the gluten-containing diet group.

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The researchers concluded that “…diabetes clinicians should be aware of CD as an important autoimmune comorbidity of type 1 diabetes that is frequently asymptomatic. In addition, clinical vigilance is warranted during dietary transition, as [treatment with a gluten-free diet] may impact short-term glycemic variability.”

Future studies should include a larger sample size and evaluate the long-term effects of a gluten-free diet in individuals with asymptomatic CD and T1D, given potentially higher risks for microvascular and skeletal complications with CD.

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

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Mahmud FH, Clarke ABM, Joachim KC, et al. Screening and treatment outcomes in adults and children with type 1 diabetes and asymptomatic celiac disease: the CD-DIET study [published online April 28, 2020]. Diabetes Care. doi:10.2337/dc19-1944