D'Anna 2013.

Methods	Type of study: parallel, randomised controlled trial.
Participants	220 women from Italy. Eligibility criteria: first‐degree relative (mother, father or both) affected by type 2 diabetes, prepregnancy BMI < 30 kg/m2, fasting plasma glucose < 126 mg/dL and random glycaemia < 200 mg/dL, singleton pregnancy, Caucasian. Women were 12‐13 weeks' gestation at trial entry. Exclusion criteria: pre‐pregnancy BMI ≥ 30 kg/m2, previous GDM, pre‐gestational diabetes, first trimester glycosuria, first‐degree relative (mother or father) not affected by type 2 diabetes, fasting plasma glucose ≥ 126 mg/dL or random glycaemia ≥ 200 mg/dL, twin pregnancy, associated therapy with corticosteroids, polycystic ovarian syndrome. Location: Department of Gynecology and Obstetrics, University of Messina, Messina, Italy. Timeframe: 2010‐2012.
Interventions	Intervention: 4 g myo‐inositol plus 400 mcg folic acid daily (2 g myo‐inositol plus 200 mcg folic acid twice a day) (n = 110). Duration of myo‐inositol supplementation: from trial entry until the end of pregnancy. Comparison: 400 mcg folic acid daily (200 mcg folic acid twice a day) as 'placebo' (n = 110).
Outcomes	Maternal: incidence of GDM, gestational hypertension, caesarean section. Criteria used to diagnose GDM: IADPSG. Infant: fetal macrosomia (> 4000 g), preterm birth, shoulder dystocia, neonatal hypoglycaemia, respiratory distress syndrome.
Notes	Sample size calculation: not stated. Intention‐to‐treat analysis: yes (carried out but not reported). Losses to follow‐up: 11 women in the intervention group, and 12 in the comparison group. Funding: source of funding not stated.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"computer randomization was used."
Allocation concealment (selection bias)	Unclear risk	Method of allocation concealment not stated.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Open‐label trial. Blinding not carried out.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Primary outcome of incidence of GDM diagnosed by blood test so blinding unlikely to impact assessment of this outcome. However, other secondary outcomes are more subjective.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Overall 10% loss to follow‐up.
Selective reporting (reporting bias)	Low risk	All pre‐specified outcome measures were reported on.
Other bias	Unclear risk	Intention‐to‐ treat analysis was carried out on the available data, but was not reported in the manuscript.