The German Gestational Diabetes Study (PREG): Rationale, Methodology and Design

Introduction Since the introduction of the new International Association of the Diabetes and Pregnancy Study Groups (IADPSG) criteria for gestational diabetes mellitus (GDM) in 2012, diagnosis and treatment of GDM has improved. But even well-treated GDM might still have impact on long-term health of the mother and her offspring, though, this relation has not been conclusively studied yet. Methods The multicenter PREG study is designed to metabolically and phenotypically characterize women with a 75 g five-point oral glucose tolerance test (OGTT) during and repeatedly after pregnancy. The offspring of the study participants are followed up until adulthood with developmental tests and metabolic and epigenetic phenotyping in the PREG offspring study. By in-depth phenotyping of the mother and her offspring, we aim to elucidate the relationship of maternal hyperglycemia during pregnancy and adequate treatment and its impact on the long-term health for both. Ethics and dissemination The study protocol has been reviewed and approved by the ethics committee of the University Hospital Tübingen (protocol numbers 218/2012BO2 and 617/2020BO1), the ethics committee of the Technical University Dresden (protocol number EK263072013), the ethics committee of the medical school of the Heinrich Heine University Düsseldorf (protocol number 4051) and the ethics committee of the medical school of University of Leipzig (protocol number 038-15-09032015). The results will be disseminated through conference presentations and peer-reviewed publications. Registration The PREG study and the PREG offspring study are registered with Clinical Trials ( ClinicalTrials.gov Identifiers: NCT04270578 , NCT04722900 ). Strengths and limitations of this study The main strength of the multicenter PREG study are the in-depth phenotyping of mothers during pregnancy and repeatedly after delivery. Data acquisition and sample handling are done according to standard operating procedures in all study sites, thus, ensuring a high quality for each data point. A PREG biobank is set up and samples are available for researchers of the German Center for Diabetes Research (DZD). Children of the study participants are repeatedly examined to cover the period of childhood and adolescence. The PREG study is not planned as a population-based cohort but is enriched for GDM cases. Data Availability Statement All requests for data and materials will be promptly reviewed by the Data Access Steering Committee to verify whether the request is subject to any intellectual property or confidentiality obligations. Individual-level data may be subject to confidentiality. Any data and materials that can be shared will be released via a Material Transfer Agreement.