Objective: The purpose of this study was to determine if the risk of having diabetes later in life was different in those who were gestational diabetic by Coustan criteria and not by National Diabetes Data Group criteria and those who are gestational diabetic only by National Diabetes Data Group criteria.
Study design: Between 1988 and 1990, 331 patients from the Springfield area who were diagnosed as gestational diabetic by either criteria since 1975 were examined for the development of diabetes by history or by 2-hour, 75 gm glucose tolerance test. National Diabetes Data Group criteria were used to determine normality or diabetic abnormality. Variables associated with diabetes were obtained. The data were analyzed using three groups: (1) gestational diabetic by National Diabetes Data Group criteria, (2) gestational diabetic by Coustan's criteria only, and (3) both groups 1 and 2.
Results: Group 1 had 190 (57.4%) and group 2 had 141 patients (42.6%), of which 25.3% and 25.5% had diabetic abnormality, respectively. Variables predictive for the development of diabetic abnormality were glucose tolerance test fasting value, number of gestational diabetic pregnancies, time to follow-up, and prepregnancy weight index. There were no differences in these variables between the normal patients or those with diabetic abnormality in groups 1 and 2.
Conclusion: Because Coustan criteria classify an additional 68.9% patients who have the same risk and risk factors for later development of diabetic abnormality and pregnancy complications compared with patients who are gestational diabetic by National Diabetes Data Group criteria, the criteria of Carpenter and Coustan should be adopted as the standard for diagnosing gestational diabetes.