Continuous glucose monitoring to support the diagnosis of MODY: A multicenter cross-sectional and prospective study

Aim Maturity onset diabetes of the young (MODY) is often misdiagnosed as type 1 diabetes (T1D). We proposed using continuous glucose monitoring (CGM) data as an additional tool to select patients in whom the fulfillment of classical MODY criteria should be reassessed, who may then be considered for genetic testing. Method A multicentric cross-sectional and prospective study was designed to evaluate the clinical utility of CGM in the diagnosis of MODY among adult patients initially diagnosed as T1D with active CGM data. Pre-specified CGM criteria included: glucose management indicator <7%, time in range (70–180 mg/dL [3.9–10.0 mmol/L]) >70% and coefficient of variation <36%. Those meeting these requirements were assessed for classical clinical criteria and subsequently genetic testing. Results A total of 503 subjects with T1D out of 5571 fulfilled the pre-established glycometric requirements. After reviewing their medical records, 42 of them met the classic clinical criteria for MODY and genetic testing was performed in 34 patients. Finally, we found 5 new cases of MODY (3 patients with HNF1A-MODY3, 1 patient with HNF1B-MODY5 and 1 patient with ABCC8-MODY12) and detected 3 patients with heterozygous mutations associated with the development of diabetes. Conclusion CGM added to classic clinical criteria for MODY may constitute an effective and easily implemented approach in routine clinical practice to identify patients with MODY who have been misdiagnosed as having T1D.