RFX6 maturity-onset diabetes of the young: clinical considerations and novel use of tirzepatide.

Summary: RFX6 maturity-onset diabetes of the young (RFX6-MODY) is a relatively new MODY subtype, with limited guidance on management, particularly in pregnancy. We report the clinical features and management of two female patients with RFX6-MODY and their progression during and post-pregnancy. These patients were diagnosed with type 2 diabetes mellitus (DM) at ages 13 and 19 years, initially managed on dietary modification alone. They were subsequently diagnosed with RFX6-MODY during pregnancy following calculation of MODY probability. Both required insulin during pregnancy and delivered healthy babies at 38 weeks. Three months post-delivery, tirzepatide was started for one of our patients and she has shown significant glycaemic improvement and weight loss. To our knowledge, this is the first reported use of tirzepatide in RFX6-MODY. Learning points: RFX6-MODY may present at a much earlier age than previously reported in the literature. Many patients with RFX6-MODY do not appear to require insulin at diagnosis. Tirzepatide may be a beneficial therapeutic option for managing patients with RFX6-MODY who have adequate β-cell function. Pregnancy management in patients with RFX6-MODY is similar to type 2 DM, although higher insulin doses may be required.