The Validity Of 75gms OGTT For Detection Of GDM Keeping 100gms OGTT As Gold Standard

Abstract

Objective: To determine the validity of 75gms (Oral Glucose Tolerance Test) OGTT for the detection of GDM keeping 100gms OGTT as the gold standard.

Methodology: This was a Cross-sectional validation study done at the Mother and Child Health Centre, Pakistan Institute of Medical Sciences, Islamabad. The duration of the study was Six months from the approval of the synopsis. Data was collected from  March 2019 to September 2019. Informed consent for participating in the study was taken from all 205 patients. The patients' bio data along with the hospital registration number was entered pro forma. The patients were assessed initially by History taking and examination. All pregnant women underwent a 75g oral glucose test in the 2nd trimester at 24-28 weeks of gestation. For this, the patients were sent to the MCH laboratory with overnight fasting where FBS was taken and they were given a 75 g glucose drink. Their blood sample was taken at 1-hour and 2-hour interval. Two or more elevated values out of the 3 blood samples were sufficient to diagnose GDM. Laboratory reports were reviewed and data was entered in the performa (attached) by the researcher. All the diagnosed patients were further evaluated for a 100g OGTT dose at the MCH laboratory with overnight fasting. Their FBS was studied and women were given a 100 g glucose drink and blood samples were drawn at an interval of 1, 2 and 3 hours respectively. Out of the 4 blood samples, two or more elevated values were sufficient to diagnose GDM. Lab reports were entered in the Performa.

Results: From a total of 205 patients, the sensitivity and specificity of OGTT-75 g for diagnosing GDM were 83.02% and 82.83%. However, positive predictive and negative predictive value for OGTT-75 g was 83.81% and 82% respectively. However, the overall diagnostic accuracy of OGTT-75 g was 82.93%.

Conclusion: Results of this study showed that 75 gms OGTT is highly sensitive (83.02%) and specific (82.83%) for the detection/diagnosis of gestational DM. Advanced screening and diagnosis of gestational DM, and its effective treatment not only inhibit adverse perinatal and maternal outcomes but also save the lives of both child and mother from diabetes in future.