Metabolic follow-up at one year and beyond of women with gestational diabetes treated with insulin and/or oral hypoglycaemic agents: Study protocol for the identification of a core outcomes set using a Delphi survey

Background: Gestational diabetes (GDM) is associated with an increased lifetime risk for the development of glucose abnormalities, metabolic syndrome, cardiovascular disease, depression and tumours. Despite this high risk of additional comorbidities, there is no standardised approach to the long-term follow-up of women with a previous diagnosis of GDM. Also, there is no standardisation of outcome selection and reporting in studies involving this population. This increases the risk of reporting bias and reduces the possibility of meaningful comparisons between studies. The aim of this study is to develop a protocol for a core outcome set (COS) for the metabolic follow-up at 1 year and beyond of women with previous GDM treated with insulin and/or oral hypoglycaemic agents. Methods/design: This protocol will describe the steps that will be taken in order to develop the COS. The study will consist of three parts: (1) A systematic review of the literature of the outcomes reported in previous randomised controlled trials of the follow-up at 1 year and beyond of women with GDM treated with insulin and/or oral hypoglycaemic agents; (2) A three-round, online Delphi survey with key stakeholders in order to prioritise these outcomes; and (3) A consensus meeting where the final COS will be decided. Discussion: The proposed protocol is the first step in developing a COS that will bring consistency and uniformity to outcome selection and reporting in GDM women treated with insulin and/or oral hypoglycaemic agents.