Implications of new diagnostic criteria for abnormal glucose homeostasis in women with previous gestational diabetes

OBJECTIVE - To determine the consequences of applying revised American Diab etes Association (ADA) (1997) and World Health Organization (WHO) (1998) re commendations for the classification of glucose intolerance in women with p revious gestational diabetes mellitus (GDM). RESEARCH DESIGN AND METHODS - There were 192 women with previous GDM who to ok an oral glucose tolerance test (OGTT) 1-86 months after delivery and wer e classified by WHO (1985), ADA (1997, fasting glucose), and revised WHO (1 998) guidelines. RESULTS - Among the 165 women without a preexisting diagnosis of diabetes, WHO-1985 and ADA-1997 provided similar estimates of diabetes prevalence (13 .3% vs, 11.5%) but widely differing estimates of impaired glucose homeostas is (31.5% impaired glucose tolerance [IGT] by WHO-1985 vs. 10.9% impaired f asting glucose by ADA-1997 criteria). Overall, 56 women (34%) showed a clas sification discrepancy between WHO-1985 and ADA-1997 criteria, including 44 with normal fasting glucose by ADA-1997 criteria, but abnormal 2-h glucose by WHO-1985 criteria (40 IGT, 4 diabetes). The cardiovascular risk profile of these women was more favorable than that of 18 women with impaired fast ing glucose. WHO-1998 recommendations reproduced ADA-1997 findings when use d as a fasting screen, but behaved similarly to WHO-1985 criteria when 2-h glucose values were also analyzed. CONCLUSIONS - All criteria produced similar estimates of diabetes prevalenc e However, analyses based on a single fasting glucose screen (and a thresho ld of 6.1 mmol/l) failed to identify 60% of women with abnormal 2-h glucose levels. Screening women with previous GDM (and by analogy, other groups at high risk of diabetes) with a single fasting glucose has low sensitivity f or the detection of abnormal glucose tolerance. Recent guidelines recommend ing this approach require reevaluation.