Adequate intake of nutrients by pregnant women diagnosed with gestational diabetes mellitus (GDM) or type 2 diabetes (T2DM) is very important for appropriate weight gain and maintenance of normoglycemia without ketonuria. The aim of this study was to investigate the nutritional intake of pregnant women with GDM or T2DM who had not been provided with nutritional education regarding blood glucose management. Between June 2008 and May 2010, 125 pregnant women who had been diagnosed with GDM or T2DM and had not received any nutrition education regarding glycemic control and proper diet during pregnancy were interviewed to collect data regarding background characteristics, health-related behaviors, and course of pregnancy and instructed to record their dietary intake using a 24-hour recall method for one day. Using the collected data, the index of nutritional quality, nutrient adequacy ratio, and mean adequacy ratio values of the subjects were calculated. Analysis of the values indicated that the majority of the subjects did not meet recommended intake levels for most micronutrients and consumed an undesirable ratio of macronutrients, specifically a higher percentage of total carbohydrates than the current recommendation level. The GDM and T2DM groups obtained 56.6% and 63.6%, respectively (p = 0.012), of their calories by carbohydrate intake, which exceeded the recommended levels (125.8% in GDM groups, 141.3% in T2DM groups).