A fiber-enriched diabetic diet that contained a modest increase in dietary fiber and a commercially available fiber supplement was studied in pregnant diabetic women for its potential glucose-lowering effects. Noninsulin-requiring gestational diabetic patients were placed on a fiber-enriched diet of increasing fiber content starting with 40 gm and eventually achieving a maximum tolerable dose of 80 gm of fiber per day. Initial pilot study demonstrated that patients could not tolerate more than 40 gm of fiber-rich food. Therefore additional fiber was administered via commercially available high-fiber drink. Satisfactory patient acceptance and compliance were achieved using this method. The response curve was flat with no lowering of blood glucose with increasing dietary fiber content. Furthermore, when the group receiving the moderate-fiber dose (40 to 60 gm), the high-fiber dose (70 to 80 gm), and a third group on an American Diabetes Association recommended diet (20 gm or less of fiber) were compared, no significant difference was observed in the mean blood glucose and postprandial glucose levels. This pilot study demonstrates that high-fiber diets, although better tolerated by patients when administered in divided amounts, are not associated with a concomitant lowering of blood glucose levels in pregnant diabetic patients.