Comparison of one step glucose tolerance test (75 g GTT) and two step glucose tolerance test (100 g GTT) in screening and diagnosis of gestational diabetes mellitus

Saranya N., Suganthi M., Shanthi Dhinakaran, Navina N.


Background: Studies suggesting that increasing carbohydrate intolerance among patients not meeting the criteria for the diagnosis of GDM by two step OGTT leads to an increased rate of unfavourable maternal and perinatal outcomes. Patients with abnormal GCT results but a normal OGTT are at increased risk, as are those with one abnormal OGTT value rather than the two required for diagnosis by ADA criteria. Single value of one step GTT is enough to diagnose GDM and to improve the maternal and perinatal complications. The objective is to compare the efficacy of one step OGTT with two step OGTT in screening and diagnosis of gestational diabetes mellitus.

Methods: Hospital based analytical cross-sectional study which was conducted for 1 year among all pregnant women booked at government medical college, Alappuzha. They were subjected to detect GDM by 2 methods at 24-28 weeks.

Results: 2521 pregnant women were subjected for study, among them who were either 75 gm GTT or 50 gm GCT or both positive (332 pregnant women) were analyzed. 232 women (69.88%) were diagnosed as having gestational diabetes mellitus (GDM) by single step 75 gm GTT. Sensitivity of single step GTT was 92.4% and a false negative rate of the same was 7.6%.  False negative rate for 50 gm GCT was 35.2%.

Conclusions: Present study concluded that this one step procedure is feasible in terms of better detection rates, saving time, limiting cost on repeated visits to health centre and reducing repeated invasive sampling. Single step GTT will be used both as a screening and a diagnostic procedure for detecting GDM.


Fasting plasma glucose, Gestational diabetes mellitus, Glucose challenge test, Oral glucose tolerance test

Full Text:



Dornhorst A, Rossi M. Risk and prevention of type 2 diabetes in women with gestational diabetes. Diabetes Care. 1998;21(Suppl2):B43-9.

Sermer M, Naylor CD, Farine D, Kenshole AB. The Toronto tri-hospital gestational diabetes project: A preliminary review. Diabetes care. 1998;21:B33-42.

Cosson E. Screening and insulin sensitivity in gestational diabetes. In Abstract volume of the 40th Annual Meeting of the EASD 2004:A350.

Dornhorst A, Paterson CM, Nicholls JS, Wadsworth J, Chiu DC, Elkeles RS, et al. High prevalence of gestational diabetes in women from ethnic minority groups. Diabetic Medicine. 1992;9(9):820-5.

Beischer NA, Oats JN, Henry OA, Sheedy MT, Walstab JE. Incidence and severity of gestational diabetes mellitus according to country of birth in women living in Australia. Diabetes. 1991;40(Supplement 2):35-8.

Seshiah V, Balaji V, Balaji MS, Sanjeevi CB, Green A. Gestational diabetes mellitus in India. JAPI. 2004;52:707-11.

American Diabetic Association Clinical practice recommendations 2002. Diabetes care 2002;25(Suppl 1):147.

WHO study group prevention of diabetes mellitus-Geneva. World health Organization. 1994 (Technical report series 844). Available at:

Seshiah V, Balaji V, Balaji MS, Sekar A, Sanjeevi CB, Green A. One step procedure for screening and diagnosis of gestational diabetes mellitus. Diabetes. 2005;126:200.

Dornhorst A, Beard RW. Gestational diabetes a challenge for the future. Diabet Med. 1993;10:897-905.

Jarrett RJ. Gestational diabetes. Diabet Med. 1994;11:992-3.

Ramachandran A, Snehalatha C, Kapur A, Vijay V, Mohan V, Das AK, et al. Diabetes Epidemiology Study Group in India (DESI) 2001 High prevalence of diabetes and impaired glucose tolerance in India: National Urban Diabetes Survey. Diabetologia. 2001;44:1094-101.

Magee MS, Walden CE, Benedetti TJ, Knopp RH. Influence of diagnostic criteria on the incidence of gestational diabetes and perinatal morbidity. JAMA. 1993;269(5):609-15.

de Aguiar LG, de Matos HJ, de Brito Gomes M. Could fasting plasma glucose be used for screening high-risk outpatients for gestational diabetes mellitus?. Diabetes Care. 2001;24:954-5.

Pettitt DJ. The 75g oral glucose tolerance test in pregnancy. Diabetes Care. 2001;24:1129.

Pettitt DJ, Bennett PH, Hanson RL, Narayan KV, Knowler WC. Comparison of World Health Organization and National Diabetes Data Group procedures to detect abnormalities of glucose tolerance during pregnancy. Diabetes Care. 1994;17(11):1264-8.

Moses RG, Moses M, Russell KG, Schier GM. The 75-g glucose tolerance test in pregnancy: a reference range determined on a low-risk population and related to selected pregnancy outcomes. Diabetes Care. 1998;21(11):1807-11.

Schmidt MI, Duncan BB, Reichelt AJ, Branchtein L, Matos MC, e Forti AC, et al. Gestational diabetes mellitus diagnosed with a 2-h 75-g oral glucose tolerance test and adverse pregnancy outcomes. Diabetes Care. 2001;24(7):1151-5.

Meltzer SJ, Synder J, Morin L, Nudi M. Validation of normative data for 75 g oral glucose tolerance test (OGTT) in a Montreal pregnant population considering ethnicity. In: Matsdinsky FM, ed. Abstract book of the 64th Scientific Sessions of the American Diabetes Association, Florida. American Diabetes Association; 2004:53:A19.

Cosson E, Benthimol M, Carbilon L, Paries J, Pharisien I, Valensi P, et al. Universal screening for gestational diabetes mellitus improves maternal and fetal outcomes compared with selective screening. In: Mateclinsky FM, ed. Abstract book of the 64th Scientific Sessions of the American Diabetes. 2004;53:A61.