Current controversies for medical nutrition therapy in pregnancies complicated by diabetes include the composition and amount of carbohydrates and fats as well as optimal gestational weight gain and energy restriction. Although carbohydrate is the macronutrient with the greatest effect on glycemic control, there is little evidence for a recommended amount and type of carbohydrate or its distribution. This lack of evidence prompts an issue of debate among practitioners over the type of carbohydrate and its percent distribution throughout the day. The best indicators at this time are the results of self-monitoring of blood glucose, ketone testing, food records, and weight gain. A review of the literature provides the most current information available for medical nutrition therapy during a pregnancy complicated by diabetes and reinforces the need for further research in the form of randomized controlled trials to answer questions regarding carbohydrate modification and distribution, energy needs, and weight gain.