Dietary therapy for gestational diabetes: How long is long enough?

Objective: To determine the length of time required for dietary therapy alo ne to effect good glycemic control and whether the need for insulin treatme nt can be predicted at diagnosis of gestational diabetes mellitus (GDM). Methods: Women with GDM were treated with dietary therapy for weeks. Each m easured her blood glucose using a memory-based reflectance glucometer, and those in poor glycemic control (mean glucose exceeding 105 mg/dL) after 4 w eeks of dietary therapy were prescribed insulin. Women were stratified by f asting plasma glucose value of 3-hour glucose tolerance tests(GTTs). Results: Women with fasting glucose at or below 95 mg/dL. were significantl y more likely to achieve good glycemic control after 2 weeks of dietary the rapy than were those with values above 95 mg/dL whose control did not impro ve during the study. Receiver operating characteristic (ROC) analysis deter mined that fasting values of GTT between 91 and 95 mg/dL best predicted tha t insulin would be needed for good glycemic control. Conclusion: Women with GDM should be prescribed dietary therapy alone for a t least 2 weeks before they are prescribed insulin. In those with fasting g lucose above 95 mg/dL, insulin may be prescribed after 1 week of dietary th erapy, or at diagnosis. (Obstet Gynecol 1999;93:978-82. (C) 1999 by The Ame rican College of Obstetricians and Gynecologists.).