β-Cell Function and Glucose Tolerance in Persons With Multiple Islet Autoantibodies Randomized to a Gluten-free Diet.

Purpose: A randomized clinical trial was conducted to evaluate the impact of a gluten-free diet (GFD) on β-cell function and glucose tolerance in persons with multiple islet autoantibodies. Methods: Individuals (n = 59; median age 11 years) with multiple islet autoantibodies were recruited to a randomized clinical trial between April 2016 and April 2021. The participants were randomized to a GFD (n = 30; female n = 14) or a normal diet (ND) (n = 29; female n = 16). The study was conducted at 6 clinical research centers in Finland and Sweden, with a dietary intervention for 17 months followed by a 6-month washout on a ND. The primary outcomes were (1) the proportion of participants going from normal glucose tolerance at the time of the randomization to abnormal glucose tolerance by 18 months, (2) a change in first-phase insulin response in IV glucose tolerance tests between randomization and 18 months, and (3) a change in C-peptide area under the curve in oral glucose tolerance test between randomization and 18 months. Results: We did not find differences between participants randomized to GFD and ND in any of the glucose tolerance outcomes. No serious adverse events or adverse events related to a GFD were noted. Conclusion: Being on a GFD was not found to differ from being on a ND in preserving β-cell function or maintaining normal glucose tolerance in persons with multiple islet autoantibodies.