The One Step approach for diagnosing gestational diabetes is associated with better perinatal outcomes than using the Two Step approach: Evidence of Randomized Clinical Trials.

There is controversy regarding the diagnosis of gestational diabetes mellitus (GDM) by either the One Step or Two Step approaches. The One Step approach consists of an oral glucose tolerance test with a 75-g glucose overload with 2 hours duration that measures plasma glucose concentration at fasting state, 1 hour, and 2 hours after glucose administration. A positive result is defined as 1 value higher than 92, 180, or 153 mg/dL, respectively. 1 Metzger B.E. Gabbe S.G. Persson B. et al. International Association of Diabetes and Pregnancy Study Groups recommendations on the diagnosis and classification of hyperglycemia in pregnancy. International Association of Diabetes and Pregnancy Study Groups Consensus Panel. Diabetes Care. 2010; 33: 676-682 Crossref PubMed Scopus (507) Google Scholar , 2 American Diabetes AssociationStandards of Medical Care in Diabetes: 2012. Diabetes Care. 2012; 35: S11-S63 Crossref PubMed Scopus (2299) Google Scholar , 3 World Health Organization. Diagnostic Criteria and Classification of Hyperglycaemia First Detected in Pregnancy. Suiza: World Health Organization;2013[cited 2014 jan 30]. Available at: http://www.who.int/diabetes/publications/Hyperglycaemia_In_Pregnancy/en/index.html. Accessed January 15, 2019. Google Scholar , 4 Diagnostic criteria and classification of hyperglycaemia first detected in pregnancy: a World Health Organization Guideline. Diabetes Res Clin Pract. 2014; 103: 341-363 Abstract Full Text PDF PubMed Google Scholar The Two Step approach consists of a nonfasting oral 50-g glucose load, with a glucose blood measurement 1 hour later. A positive result is defined as a blood glucose value higher than 130, 135, or 140 mg/dL; the most common value used is 135 mg/dL. 5 American College of Obstetricians and Gynecologists Committee on Practice BulletinsObstetrics. Gestational diabetes mellitus. Practice Bulletin No. 137. Obstet Gynecol. 2013; 122: 406-416 Crossref PubMed Google Scholar A positive screening test is followed by a diagnostic test that consists of a 100-g oral glucose load with the glucose measurement fasting and after 1, 2, and 3 hours. A positive result is defined as 2 values higher than target values. Although the American College of Obstetricians and Gynecologists recommends the Two Step approach, the International Association of the Diabetes and Pregnancy Study Groups, American Diabetes Association, International Federation of Gynecology and Obstetrics, and World Health Organization recommend the One Step approach. 1 Metzger B.E. Gabbe S.G. Persson B. et al. International Association of Diabetes and Pregnancy Study Groups recommendations on the diagnosis and classification of hyperglycemia in pregnancy. International Association of Diabetes and Pregnancy Study Groups Consensus Panel. Diabetes Care. 2010; 33: 676-682 Crossref PubMed Scopus (507) Google Scholar , 2 American Diabetes AssociationStandards of Medical Care in Diabetes: 2012. Diabetes Care. 2012; 35: S11-S63 Crossref PubMed Scopus (2299) Google Scholar , 3 World Health Organization. Diagnostic Criteria and Classification of Hyperglycaemia First Detected in Pregnancy. Suiza: World Health Organization;2013[cited 2014 jan 30]. Available at: http://www.who.int/diabetes/publications/Hyperglycaemia_In_Pregnancy/en/index.html. Accessed January 15, 2019. Google Scholar , 4 Diagnostic criteria and classification of hyperglycaemia first detected in pregnancy: a World Health Organization Guideline. Diabetes Res Clin Pract. 2014; 103: 341-363 Abstract Full Text PDF PubMed Google Scholar , 5 American College of Obstetricians and Gynecologists Committee on Practice BulletinsObstetrics. Gestational diabetes mellitus. Practice Bulletin No. 137. Obstet Gynecol. 2013; 122: 406-416 Crossref PubMed Google Scholar , 6 Thompson D. Berger H. et al. Canadian Diabetes Association Clinical Practice Guidelines Expert CommitteeDiabetes and pregnancy. Can J Diabetes. 2013; 37: S168-S183 PubMed Scopus (156) Google Scholar , 7 Hod M. Kapur A. Sacks D.A. et al. The International Federation of Gynecology and Obstetrics (FIGO) Initiative on gestational diabetes mellitus: a pragmatic guide for diagnosis, management, and care. Int J Gynaecol Obstet. 2015; 131: S173-S211 Crossref PubMed Scopus (567) Google Scholar