659-P: The Effectiveness of Lifestyle, Metformin, or Dietary Supplements for the Prevention of Gestational Diabetes Mellitus (GDM) by Intervention Characteristics—A Systematic Review and Meta-analysis

Systematic reviews examining the effectiveness of interventions for GDM prevention have reported inconsistent results. Intervention characteristics such as intervention type, provider, delivery mode (individual, group or both), the use of theory, intervention location (home- or centre-based), duration, frequency, monitoring (supervised or unsupervised) and other characteristics have not been thoroughly investigated and likely impact intervention efficacy. This study was a systematic review and meta-analysis of controlled trials on lifestyle (diet and/or exercise), metformin and dietary supplementation. The impact of intervention characteristics on GDM prevention was conducted using the ‘Template for Intervention Description and Replication framework’. Overall, 116 studies were included. For lifestyle interventions (n=92), lower risks of GDM were observed in studies with supervised sessions (n=13, RR 0.63, 95% CI 0.50-0.79, p=0.04) compared with those with unsupervised sessions, with group-only delivery (n= 17, RR 0.61, 95% CI 0.51-0.74, p=0.04) compared with those with a combination of individual and group delivery, and in low-middle income countries (n=7, RR 0.58 95% CI 0.42-0.8, p=0.03) compared with studies conducted in middle or high-income countries. Lifestyle intervention effect sizes did not differ by any other intervention characteristics. No significant effect of intervention characteristics was seen in metformin studies (n=13). For dietary supplementation studies (n=12), lower risks of GDM were observed with myoinositol (n=7, RR 0.38, 95% CI 0.23-0.65) but not with probiotics (n=5, RR 0.88, 95% CI 0.52-1.47). Country setting, delivery mode, session supervision may be important characteristics determining the effectiveness of GDM prevention. Further research is needed to tailor these intervention approaches for specific populations. Disclosure W.W.Takele: None. S.J.Zhou: None. R.Taylor: None. M.Pathirana: None. K.Liu: None. M.P.Bonham: None. M.Chen: None. A.J.Fawcett: None. S.C.Chivers: None. S.Lim: None. G.G.Ukke: None. J.L.Josefson: None. K.K.Vesco: Research Support; Pfizer Inc. L.M.Redman: Research Support; Dexcom, Inc., Abbott Nutrition, National Institute of Diabetes and Digestive and Kidney Diseases, Stock/Shareholder; ABGIL, Teladoc Health. J.A.Grieger: None. N.Habibi: None. A.Quinteros: None. G.Leung: None.