CLASS-A(1) GESTATIONAL DIABETES - A MEANINGFUL DIAGNOSIS

Objective: To compare pregnancy outcomes in women diagnosed as having class A1 gestational diabetes with those of a group with a normal 3-ho ur glucose tolerance test (GTT) to assess morbidities attributable to glucose intolerance. Methods: Selective 50-g GTT identified pregnant w omen who received a 3-hour GTT. Over a 16-month period, 159 women were diagnosed as having class A1 gestational diabetes according to the Na tional Diabetes Data Group criteria. During the latter 12 months of th is time period, 151 women who had a normal GTT result were identified for comparison. Results: There were statistically significant differen ces in age and the development of peripartum hypertension in women wit h class A1 gestational diabetes compared with the normal 3-hour GTT gr oup. There were no significant differences in any neonatal outcome var iable, including percent delivering large for gestational age (LGA) ne onates in women with A1 diabetes compared to controls. Overall, 111 (3 6%) of the 310 neonates were classified as LGA, a rate more than doubl e that in the singleton population in our hospital. Maternal weight, p arity, and a history of a previous macrosomic infant were significantl y associated with LGA outcome. Mean maternal weight was the same in th e two GTT groups, implying an independent effect on fetal size. Obstet ric interventions were not significantly different between the groups, so differences in intervention could not account for the lack of diff erence in outcome variables. The impact of dietary counseling in the c lass A1 diabetic women is also an unlikely explanation for the lack of differences in outcome. Within the normal-GTT group, women with one a bnormal 3-hour value had a frequency of LGA infants similar to that of women with all normal 3-hour GTT values. These results suggest that t here is a selection effect of screening for glucose intolerance that m ay relate more to other risk factors for LGA outcome than to glucose i ntolerance. Maternal obesity is an independent and more potent risk fa ctor for large infants than is glucose intolerance. Conclusion: The di agnosis of class A1 gestational diabetes is not significantly associat ed with obstetric and perinatal morbidities. A nondiscriminating diagn ostic test undermines the validity of population screening for glucose intolerance.