Langer 1989.

Methods	Randomised controlled trial.
Participants	126 women with a positive 50 g 1‐hour GCT (≥130 mg/dl) and with one abnormal value in 100 g 3‐hour OGTT according to NDDG criteria. Setting: Bronx, New York, USA.
Interventions	Women (n = 63) in the intervention group Capillary blood glucose monitoring: 7 times a day. Diabetic management protocol: 25 kcal/kg/day for women pre‐pregnancy BMI ≥ 27 kg/m2 and 30 kcal/kg/day for women pre‐pregnancy BMI < 27 kg/m2. Insulin therapy when diet alone is not able to achieve the tight glycaemic control of 95 mg/dl. The insulin dose was calculated based on 0.7 U of insulin per kg of body weight measured in pregnancy. Human insulin was administered by multiple insulin injection regimen. The standard formula for the amount of insulin prescribed was two thirds of all insulin in the morning (2:1, intermediate‐acting/ regular insulin) and one third in the evening (1:1. regular/intermediate‐acting). Women (n = 63) in the control group Habitual routine diet. Capillary BGL monitoring for a baseline period of 4 weeks.
Outcomes	Maternal: gestational age at delivery, weight gain, caesarean section; hypertensive disorders. Infant: birthweight, LGA (birthweight ≥ 90th Centile); SGA (birthweight ≤ 10th centile); preterm birth (< 37 weeks' gestation); hypoglycaemia (BGL < 35 mg/dl or 1.94 mmol/l); hyperbilirubinaemia (bilirubin > 12 mg/dl); hypocalcaemia (calcium < 7.5 mg/dl); polycythemia (central venous hematocrit > 62%); admission to neonatal intensive care unit; respiratory distress syndrome.
Notes	The NDDG criteria (adopted by ADA and ACOG at the time of study) Fasting: > 105 mg/dl (5.8 mmol/l). 1‐h: > 190 mg/dl (10.6 mmol/l). 2‐h: > 165 mg/dl (9.2 mmol/l). 3‐h: > 145 mg/dl (8.1 mmol/l). 2 or more of the values must be met or exceeded for GDM diagnosis. All women were instructed to add 150 g of carbohydrate to their usual meals for each of 3 days before their 100‐g OGTT.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Described as “randomised into treated and untreated groups.”
Allocation concealment (selection bias)	Unclear risk	No information was given on allocation concealment.
Blinding of participants and personnel (performance bias) All outcomes	High risk	It is unlikely to blind study participants. No information on whether research personnel was blinded or not.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	No information about whether outcome assessors were blinded.
Incomplete outcome data (attrition bias) All outcomes	Low risk	No loss to follow‐up or post randomisation exclusion.
Selective reporting (reporting bias)	Low risk	No obvious risk of selective reporting.
Other bias	Low risk	No obvious risk of other bias.

ACOG: American Congress of Obstetricians and Gynecologists ( formerly the American College of Obstetricians and Gynecologists) 
 ADA: American Diabetes Association 
 BGL: blood glucose level 
 GCT: glucose challenge test 
 GDM: gestational diabetes mellitus 
 GI: glycaemic index 
 IGTP: impaired glucose tolerance of pregnancy 
 LGA: large for gestational age 
 NDDG: National Diabetes Data Group 
 OGTT: oral glucose tolerance test