Diagnosis of Gestational Diabetes in Early Pregnancy

  1. Satish C Kalhan, MBBS, FRCP
  1. Departments of Pediatrics and Obstetrics and Cynecology, Case Western Reserve University School of Medicine, MetroHealth Medical Center, Rainbow Babies and Childrens Hospital Cleveland, Ohio
  1. Address correspondence and reprint requests to Dennis M. Super, MD, MPH, Department of Pediatrics, H449, MetroHealth Medical Center, 3395 Scranton Road, Cleveland, OH 44109.

Abstract

Objective To determine whether glucose intolerance can be identified early in gestation in a high-risk population so that early intervention can be planned to prevent associated morbidity.

Research Design and Methods After appropriate dietary preparation, patients with a high risk for gestational diabetes underwent a 50-g oral glucose screening test during fasting. Patients were tested on enrollment and every 10 wk until delivery. Those with a 1-h plasma glucose value of ≥7.5 mM underwent a 100-g oral glucose tolerance test. Gestational diabetes was based on either a markedly abnormal 50-g screening test or abnormal 100-g oral glucose tolerance test.

Results Ten of 15 (66%) patients who developed gestational diabetes were diagnosed during the first half of the pregnancy. Six were diagnosed in the first trimester. If the definition of an abnormal 1-h plasma glucose value was lowered from 7.5 to 7.2 mM, an additional 2 patients could have been identified in the first trimester with an improvement in sensitivity from 70 to 91% with only a slight drop in specificity (from 91 to 88%). Diagnosis of gestational diabetes was not enhanced by measuring plasma insulin concentrations or insulin-glucose molar ratios.

Conclusions The diagnosis of gestational diabetes in a high-risk population can be made in the first half of pregnancy. Early diagnosis should permit evaluation of intervention strategies, which may result in improved perinatal outcome.

  • Received March 5, 1990.
  • Accepted November 5, 1990.
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