Voormolen 2018.

Methods	Nationwide multicentre, open‐label, parallel, pragmatic randomised controlled trial Period of study: July 2011 to September 2015
Participants	Number randomised: 300 pregnant women type 1 (n = 109), type 2 (n = 82), or with gestational diabetes (n = 109). Inclusion criteria: pregnant women with pre‐existing DM, at gestational age of before 16 weeks, or had GDM requiring insulin therapy before 30 weeks gestational age. Exclusion criteria: women with multiple pregnancies, under 18 years of age, or who had severe medical or psychological comorbidity
Interventions	Intervention: CGM:iPro2 (Medtronic, Northridge, California) ‐ CGM in addition to standard care – self‐monitoring. Women allocated to CGM were instructed to use the device for 5‐7 days every 6 weeks and glucose profiles were obtained retrospectively, directly after each use and evaluated by the local endocrinologist. SMBG is required for calibration of CGM. Readings from the CGM are uploaded to a web‐based program; (n = 147 all women, 50 with T1DM, 40 T2DM). Control: standard treatment ‐ self‐monitoring of blood glucose only (n = 153 all women, 97 with type 2 diabetes). All participants in both intervention and control groups performed SMBG (4‐8 times/day: at least fasting, after every meal, at bedtime and, preferably before every meal).
Outcomes	Outcomes used in this review Hypertensive disorders of pregnancy (including pre‐eclampsia, pregnancy‐induced hypertension, eclampsia). Caesarean section*. Large‐for‐gestational age*. Induction of labour*. Glycaemic control during/end of treatment (as defined by trialists) (e.g. HbA1c, fructosamine, fasting blood glucose, post‐prandial blood glucose)*. Instrumental vaginal birth*. Neonatal mortality. Gestational age at birth*. Preterm birth*. Macrosomia (≥ 4000 g). Small‐for‐gestational age (< 10th centile)*. Birthweight and z‐score (birthweight g) mean (SD)*. Shoulder dystocia*. Neonatal hypocalcaemia*. Major and minor anomalies – congenital anomaly*. Neonatal intensive care unit admission*. Birth trauma (shoulder dystocia, bone fracture, nerve palsy) (not pre‐specified as a composite) – birth injury and shoulder dystocia*. * outcome not reported separately for pre‐gestational and gestational diabetes
Notes	Setting: 22 hospitals (university, teaching and non‐teaching in the Netherlands and 1 university hospital in Belgium. Country: the Netherlands. Funding: the trial was funded by ZonMw, The Dutch Organization for Health Research and Development 80‐82310‐97‐11157. The funder had no role in the study design, data collection, data analysis, data interpretation or writing of the report. Continuous glucose monitors were purchased at a discounted price from Medtronic® and they had no role in the study design, data collection, data analysis, data interpretation, or writing of the report. Declarations of interest: 1 of the trial authors received a research grant from ZonMW (the Netherlands Organization for Health Research and Development) and a second author received research grants from Abbott, Dexcom, Medtronic and Sensonics, and also received personal fees from Roche Diabetes Care and Sensonics. A third author is supported by an NHMRC Practitioner Fellowshop (GNT1082548) and reports consultancy for ObsEVa, Merck and Guerbet. All other authors declare no support from any organization or conflict of interest. Comments A sample size calculation was reported. They included both women with pre‐gestational diabetes (type 1 and type 2) and women with GDM. However, for most of our review outcomes, the data were not separated out by pre‐gestational and GDM women. The study was approved by the ethics committee of the Academic Medical Centre Amsterda, (reference number MEC AMC 10/322) and by the boards of management of all participating hospitals. Written consent was obtained from all participating women.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Web‐based computerised programme using 1:1 randomisation, stratified according to type of diabetes
Allocation concealment (selection bias)	Unclear risk	Not clearly described
Blinding of participants and personnel (performance bias) All outcomes	Low risk	No blinding – but outcome measures mainly objective, so unlikely to be affected by lack of blinding
Blinding of outcome assessment (detection bias) All outcomes	Low risk	No blinding – but outcome measures mainly objective, so unlikely to be affected by lack of blinding
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	High number of patients refused continued use of the CGM after the first or second time – a total of 66% of participants used CGM according to study protocol. However, there was a clear flow of participants in trial profile figure and reasons for dropouts, withdrawal provided. Conducted analyses on intention‐to‐treat and per‐protocol basis; 4 drop‐outs from CGM group and 6 from standard group so primary analyses were carried out according to the intention‐to‐treat principle – 143/147 included from the (CGM group) and 147/153 (standard group in the intention‐to‐treat analysis). Quite a high drop out rate – 95 women in the CGM group and 144 from the control group were included in the per‐protocol analyses. 48 discontinued intervention and 3 discontinued protocol for standard group leaving: 95/147 (66%) intervention group and 144/153 (98%) standard group
Selective reporting (reporting bias)	High risk	Maternal outcomes not reported Severe hypoglycaemia Neonatal outcomes not reported Preterm birth < 37 weeks' gestation Birth trauma Culture proven sepsis Respiratory distress syndrome Bronchopulmonary dysplasia Intraventricular haemorrhage Necrotising enterocolitis The above were outcomes in the methods of the full report – but were not presented in the results section. The protocol also reported the following outcomes that were not reported in the results: mode of delivery, perinatal death, glucose variability, costs and resource utilisation
Other bias	Unclear risk	Baseline characteristics – groups were similar. Data not presented separately for pre‐gestational diabetes (type 1 and type 2 diabetes) and GDM patients for most of the outcomes.