Effects of new criteria for type 2 diabetes on the rate of postpartum glucose intolerance in women with gestational diabetes

OBJECTIVE: Our purpose was to determine the impact of the 1997 American Dia betes Association diagnostic criteria for type 2 diabetes mellitus an the r ats of postpartum glucose intolerance in women with gestational diabetes. STUDY DESIGN: Women identified as having gestational diabetes were instruct ed to undergo a 75-g, 2-hour glucose tolerance test 4 to 6 weeks after deli very. The results were retrospectively categorized with both the 1979 Natio nal Diabetes Data Group criteria and those recommended by the American Diab etes Association in 1997. RESULTS: Though the rate of overt diabetes mellitus did not increase when t he 1997 American Diabetes Association criteria were used (7.8% vs 5.6%, P = not significant), the rate of impaired glucose metabolism was higher (20.1 % vs 5%, P<.001). Most women (28/30, 93%) with a nondiagnostic glucose tole rance test result by the older criteria had abnormal results by the newer c riteria. Fifty women had abnormalities of glucose metabolism under 1997 Ame rican Diabetes Association criteria; 34% of these women had fasting plasma glucose values in the normal range. Of the 25 women with impaired glucose t olerance, 16 (64%) had only an abnormal 2-hour value, with normal fasting g lucose values. CONCLUSIONS: The rate of postpartum abnormalities in glucose metabolism mor e than doubles when the 1997 American Diabetes Association criteria are app lied; more women are identified with lesser degrees of impairment. However, relying on fasting glucose levels alone, without glucose tolerance testing , may miss one third of women with such abnormalities.