Trials comparing a package of care starting with dietary modification to routine care and trials comparing a dietary modification with another dietary modification
| First author | Year | Location | No | Screening strategy used to determine need for diagnostic test | Diagnostic test and glucose thresholds used to diagnose GDM (mmol/L) | Intervention group | Control group | Insulin use in diet group | In meta-analyses | Meta-analysis outcome |
| Trials comparing a package of care (starting with dietary modification) to routine care | ||||||||||
| Bevier45 | 1999 | USA | 103 | 50 g OGCT >7.8 | Positive OGCT, negative 100 g OGTT, levels not reported | Dietary counselling and home monitoring | Routine care | If needed | Yes | Apgar 5 min, BW, C-section, GA at birth, induction, instrumental birth, macrosomia, pre-eclampsia, shoulder dystocia |
| Bonomo46 | 2005 | Italy | 300 | Risk factors and 50 g OGCT | Positive OGCT >7.8, negative 100 g OGTT ‘C&C criteria’ | Dietary advice and monitoring | Routine care | Not reported | Yes | Apgar 5 min, BW, C-section, GA at birth, LGA, macrosomia, NN hypoglycaemia, NICU admission |
| Crowther47 | 2005 | UK/Australia | 1000 | Risk factors or 50 g OGCT | 75 g OGTT fasting <7.8 and 2 hours >7.8 and <11.1 | Individualised dietary advice, monitoring and pharmacological treatments | Routine care | If needed | Yes | Apgar 5 min <7, BW, C-section GA at birth, induction, macrosomia, NN hypoglycaemia, NICU admission, pre-eclampsia, shoulder dystocia |
| Deveer33 | 2013 | Turkey | 100 | Universal 50 g OGCT >7.8 and <10.0 | Positive OGCT, negative 100 g OGTT fasting <5.3, 1 hour <10.0, 2 hours <8.8 and 3 hours <7.8 | Calorie diet | Routine care | Not reported | Yes | BW, C-section, GA at birth, LGA, macrosomia, NICU admission, pre-eclampsia, preterm birth |
| Elnour48 | 2006 | UAE | 180 | Not reported | 100 g OGTT, ‘C&C criteria’ | Diet education, exercise, monitoring and pharmacological treatments | Routine care | If needed | Yes | C-section, LGA, macrosomia, NN hypoglycaemia, NICU admission, pre-eclampsia, preterm birth, shoulder dystocia |
| Fadl34 | 2015 | Sweden | 66 | Risk factors | 75 g OGTT<7.0, >10.0, <12.2 | Diet education, exercise, monitoring and pharmacological treatments | Routine care | If needed in intervention group only | Yes | BW, C-section, LGA, GA at birth, macrosomia, pre-eclampsia, instrumental birth, induction, NICU admission |
| Garner49 | 1997 | Canada | 299 | 75 g OGCT >8.0 | 75 g OGTT fasting >7.5 and 2 hours >9.6 | Dietary counselling, restricted calorie intake, monitoring and insulin if required | Routine care | If needed | Yes | BW, C-section, GA at birth, macrosomia, NN hypoglycaemia, pre-eclampsia, preterm birth, shoulder dystocia |
| Landon50 | 2009 | USA | 958 | 50 g OGCT >7.5 to <11.1 | 100 g OGTT fasting <5.3, 2 or more, 1 hour >8.6 or 2 hours >8.6 | Individualised dietary advice, monitoring and insulin | Routine care | If needed | Yes | BW, C-section, GA at birth, induction, macrosomia, NN hypoglycaemia, NICU admission, pre-eclampsia, preterm birth, shoulder dystocia |
| Li51 | 1987 | Hong Kong | 58 | Risk factors | 100 g OGTT, two or more: fasting >5.8, 1 hour >10.6, 2 hours >9.2, 3 hours >8.1, then 75 g OGTT fasting <8.0 or 2 hours <11.0 | 30–35 g/kg carbohydrate diet and monitoring | Routine care | Not reported | Yes | BW, C-section, GA at birth, induction, macrosomia |
| O'Sullivan52 | 1966 | USA | 615 | OGCT or risk factors | 100 g OGTT two or more fasting >6.1, or 1 hour >9.1 or 2 hours >6.7 or 3 hours >6.1 | Low-calorie diabetic diet | Standard diabetic diet | Only in intervention group | Yes | Macrosomia, preterm birth |
| Yang35 | 2003 | China | 150 | Not reported | Not reported | ‘Intensive’ diabetes management | Routine care | If needed | Yes | C-section, shoulder dystocia |
| Yang36 | 2014 | China | 700 | 75 g OGTT fasting 5.1, 1 hour 10.0, 2 hours 8.5 | Individual and group dietary/physical intervention | Routine care | If needed | Yes | BW, C-section, GA at birth, induction, macrosomia, NN hypoglycaemia, PIH, pre-eclampsia, preterm birth, shoulder dystocia | |
| Trials comparing a dietary modification with another dietary modification | ||||||||||
| Asemi53 | 2014 | Iran | 52 | 50 g OGCT | OGCT >7.8, 75 g OGTT fasting >5.1, 1 hour >10.0, 2 hours >8.5 | DASH diet | Control diet | Women with GDM excluded, therefore insulin not required | No | – |
| Cypryk54 | 2007 | Poland | 30 | Not reported | Levels not reported only that the WHO criteria were used | High-carbohydrate diet | Low-carbohydrate diet | If needed | No | – |
| Louie55 | 2011 | Australia | 99 | Not reported | 75 g OGTT ≥5.5, 1 hour >10.0 or 2 hours >8.0 | Low-GI diet | High-fibre moderate-GI diet | If needed | No | – |
| Ma37 | 2015 | China | 83 | 50 g OGCT | 75 g OGTT ≥5.8, 1 hour >10.6, 2 hours >9.2 or 3 hours 8.1 | Low glycaemia load diet | Usual diet | If needed* | No | – |
| Moreno-Castilla56 | 2013 | Spain | 152 | 50 g OGCT >7.8 | 100 g OGTT >5.8, 1 hour >10.6, 2 hours >9.2, 3 hours >8.1 | Low-carbohydrate diet | Control diet | If needed | No | – |
| Rae57 | 2000 | Australia | 124 | Not reported | (Glucose load not reported) OGTT fasting >5.4 or 2 hours >7.9 | Calorie-restricted diet | Usual diet | If needed | No | – |
| Yao38 | 2015 | China | 33 | 50 g OGCT fasting >5.8 ‘post-load’ >7.8 | 100 g OGTT fasting >5.3, 1 hour >10.0, 2 hours >8.6, 3 hours >7.8 | DASH diet | Usual diet | If needed | No | – |
↵*Women who required insulin were excluded from the trial’s analyses.
BW, birth weight; C-section, caesarean section; DASH diet, dietary approaches to stop hypertension; GA; gestational age; GDM, gestational diabetes mellitus; LGA, large for gestational age; NICU, neonatal intensive care unit; NN, neonatal; OGCT, oral glucose challenge test; OGTT, oral glucose tolerance test; PIH, pregnancy-induced hypertension.