Gestational diabetes mellitus (GDM) is the most common medical disorder complicating pregnancy that requires the services of a registered dietitian. Despite three international workshops on GDM, many questions remain regarding its epidemiology, pathophysiology, screening, diagnosis, and management. Registered dietitians encounter these controversial issues when working with women referred for GDM education and counseling. Nutrition intervention remains the cornerstone of therapy. The purpose of this article is not to provide practice guidelines but to review the literature and current practices in research centers across the United States. Registered dietitians are in a position to individualize nutrition care to each woman's needs and to participate in the decision-making process of nutrition management.