The primary aim of this pilot study was to test the protocol for a larger scale RCT of either immediate or deferred treatment for Booking GDM. Clinic midwives at the Campbelltown Hospital Book-in clinic (i.e. first antenatal clinic attendance) assessed the need of all pregnant women for early testing for Diabetes in Pregnancy, based upon GDM Risk factors [10]. Women are referred for a 75 g, 3 point, 2 h oral glucose tolerance test (OGTT) as per local policy. Between July 20th 2015 and April 7th 2016, consecutive pregnant women at 4 to 19 + 6 weeks gestation, with a singleton pregnancy, aged ≥18 years and referred for an OGTT were invited to participate. Exclusions were inability to understand English, or a presence of a major active medical disorder. Consenting women completed questionnaires at baseline, 24–28 and 34–38 weeks and attended a study OGTT appointment. Other data were extracted from the clinical notes.
OGTT results were sent to one investigator (DS). Women with Diabetes In Pregnancy (fasting ≥7.0 and/or 2 h ≥ 11.1 mmol/l) were referred immediately to the clinic for treatment. Women below the 24–28 week GDM [4] criteria (fasting ≥5.1 and/or 1 h ≥ 10.0 mmol/l and/or 2 h ≥ 8.5 mmol/l), were advised that they did not require referral to the clinic (‘decoys’). Such decoys blinded the obstetric team as to whether women involved in ToBOGM were controls or women without ‘hyperglycaemia’. Women fulfilling criteria for GDM were randomised to either referral to the clinic (Treated) or were advised (using identical letters to the ‘decoys’) that they did not require referral to the clinic (No Treatment). The participant, as well as midwifery, obstetric, diabetes clinic, and research staff were kept blinded to all numeric results and only knew if a woman had been referred for GDM treatment. Randomisation to either immediate or deferred treatment was undertaken using an electronic randomiser (SPSS Version 22.0, IBM, USA), stratified as either low risk (fasting 5.1–5.2 mmol/l, 1 h 10–10.5 mmol/l and /or 2 h 8.5–8.9 mmol/l) or high risk (based upon the IADPSG 2 fold excess risk of adverse outcomes at 24–28 weeks gestation [6]: fasting 5.3–6.9 mmol/l, 1 h ≥ 10.6 mmol/l and /or 2 h 9.0–11.0 mmol/l).
All women receiving treatment for GDM received group education, were taught to self-monitor blood glucose and saw a dietitian. Fasting and 2 h post-prandial glucose targets were < 5.3 mmol/l and < 6.8 mmol/l respectively [5]. Where glucose thresholds were exceeded on more than two occasions with no obvious cause, women were offered medication (metformin or insulin treatment). Only women not referred to clinic attended a 24–28 week OGTT, and were referred for treatment if GDM was diagnosed.
All women were asked for their baby to provide a heel prick glucose 1–2 h after birth. Venous umbilical cord blood was drawn into EDTA tubes for assessing a range of metabolites and assessing the adipo-insular axis. Glucose, triglyceride and 3-beta hydroxy butyrate were measured in a single International Organization for Standardization accredited laboratory. Plasma insulin and C-peptide levels were measured using a sandwich chemiluminescence immunoassay (Liaison XL, Diasorin, Saluggia, Italy). Leptin and adiponectin measurements were determined using a radioimmunoassay kit (Merck Millipore, Darmstadt Germany).
Qualitative assessment
Midwives at Campbelltown Hospital completed a survey prior to the pilot study commencing. An additional one hour focus group was conducted with a group of midwives (n = 6) at the conclusion of the pilot study, to examine their experience of taking part in the RCT. A survey was also completed by mothers who were booked into the clinic at Campbelltown Hospital for antenatal care. A group of mothers (n = 4) also took part in a focus group at the conclusion of the pilot study. The midwife and the mothers’ surveys both contained demographic questions, closed ended questions about knowledge of GDM and open ended questions about expectations and experiences of the pilot study protocol. In the focus groups, the midwives and mothers were asked about their expectations and experiences of GDM and the study protocol. The focus groups were audio recorded and transcribed verbatim. Focus group transcripts and open ended interviews were analysed using thematic analysis [11]. This involved reading through the qualitative data, developing a coding frame based on commonality of responses across participants, leading to identification of themes that captured expectations and experiences of GDM and involvement in the study. The themes included acceptability, unacceptability, concerns, absence of concerns, and importance of mothers consent.
Statistics
As a pilot, limited by funding, a target was set to randomise 20 women with GDM at booking, with an expectation, based upon a prior study [12], that 100 women would need to be consented to meet this target. Mean and standard deviations are reported for continuous variables, and number and percentages are reported for categorical variables. Geometric mean is used for non-normally distributed biochemical measurements [13]. All tests are 2 tailed. Analyses were undertaken using SPSS Version 22.0 (IBM, USA) with proportions compared using Chi squared test and continuous variables compared using Analysis of Variance. The study was approved by the South Western Sydney Local Health District Ethics committee (reference 15/LPOOL/14).
