Proinsulin in the identification and risk stratification of gestational diabetes mellitus: study protocol for a prospective, longitudinal cohort study.

introductionGestational diabetes mellitus (GDM) is a common metabolic disorder occurring in up to 10% of pregnancies in the western world. Most women with GDM are asymptomatic; therefore, it is important to screen, diagnose and manage the condition as it is associated with an increased risk of maternal and perinatal complications. Diagnosis of GDM is made in the late second trimester or early third trimester because accurate diagnosis or risk stratification in the first trimester is still lacking. An increase in serum proinsulin may be seen earlier in pregnancy and before a change in glycaemic control can be identified. This study will aim to establish if fasting proinsulin concentrations at 16-18 weeks gestation will help to identify or risk stratify high-risk pregnant women with GDM. METHODS AND ANALYSIS: This is a prospective, longitudinal cohort study. Two oral glucose tolerance tests will be carried out at 16-18 and 24-28 weeks gestation in 200 pregnant women with at least one risk factor for GDM (body mass index>30 kg/m ETHICS AND DISSEMINATION: This study received ethical approval from the Wales Research Ethics Committee (Panel 6) (Ref. 17/WA/0194). Data will be presented at international conferences and published in peer-reviewed journals. TRIAL REGISTRATION NUMBER: ISRCTN16416602; Pre-results.