Do continuous glucose monitoring (CGM) metrics predict macrovascular and microvascular complications in diabetes? The FACULTY protocol of a retrospective real-world cohort study.

Introduction: Glycated haemoglobin (HbA1c) is currently the gold standard for assessing glycaemic control in diabetes, given the established relationship with microvascular and macrovascular complications in this condition. However, HbA1c is affected by non-glycaemic factors, while also failing to provide data on hypoglycaemic exposure and glucose variability, which are associated with adverse vascular outcomes. Continuous glucose monitoring (CGM)-derived glucose metrics provide a more comprehensive assessment of glycaemia, but their role in predicting future vascular complications remains unclear. Here, we present the protocol for a real-world cohort study, aiming to establish the relationship between CGM-derived glycaemic metrics and the incidence of macrovascular and/or microvascular complications in people with diabetes.

Methods And Analysis: This cohort study will use data from all CGM new users (FreeStyle Libre system) in France who uploaded their glycaemic values onto the LibreView cloud-based system, linked with data from the French nationwide claims database. The study is expected to include a minimum of 70 000 individuals with diabetes with a first date of glucose data upload to the LibreView platform after 1 January 2018 and with a 6-year follow-up period. The primary outcomes are the first occurrence of new macrovascular or microvascular complications, analysed as a composite outcome and separately. Secondary outcomes will include all-cause mortality and hospital admissions for any cause. This longitudinal study will provide key data on the relationship between CGM-derived glycaemic metrics and micro/macrovascular complications in diabetes. This will have an impact on routine clinical practice by setting targets for the different glycaemic markers, based on robust outcome data, thus helping to optimise glucose management in diabetes.

Ethics And Dissemination: The study data-collection protocol is approved by the French National Commission for Informatics and Liberties, including approval from the . This study complies with French and European regulations, including those relating to the General Data Protection Regulation. This study uses pseudonymous information, not requiring informed consent. Dissemination plans include full publication of the study outcomes in peer-reviewed journal(s) with open access and presentations at national and international diabetes and cardiovascular conferences.