NEW YORK (Reuters Health) – A low-glycemic index diet can significantly reduce the need for insulin in women with gestational diabetes, without compromising maternal or fetal outcomes, according to a new study.

Researchers have known that women with gestational diabetes can reduce postprandial glycemia by eating mixed meals based on low-glycemic index foods, and such a diet “is commonly advised as treatment for women with gestational diabetes mellitus,” Dr. Robert G. Moses and co-investigators write in the June issue of Diabetes Care. “However, the efficacy of this advice and associated pregnancy outcomes have not been systematically examined.”

To investigate, Dr. Moses, at the South Eastern Sydney and Illawarra Area Health Service in Wollongong, New South Wales, and his team enrolled 62 women with gestational diabetes at about 30 weeks gestation in their randomized trial.

Thirty-one were assigned the low-glycemic index diet and 32 were assigned a high-fiber/low-sugar diet (the high-glycemic index diet). Both diets recommended a minimum carbohydrate intake of 175 g/d, with only the choice of carbohydrate foods varying.

Women on the low-glycemic index diet were counseled on the energy and nutrient balance of various foods, and were asked to avoid certain foods including white bread and processed commercial breakfast cereals. Women in the high-glycemic index diet group “were advised to follow a diet with a high-fiber and low-sugar content, with no specific mention of the glycemic index.”

At a mean of 32 weeks, 9 women in the low-glycemic diet (29%) and 19 (59%) in the high-glycemic diet met the study’s requirements insulin (p = 0.023).

However, once patients on the high-glycemic index diet required insulin, they were switched to the low-glycemic index diet, at which point 9 no longer met the criteria for starting insulin. Both groups on the modified diet achieved a similar glycemic index value by the final visit at 35-37 weeks of gestation.

“Overall,” the authors report, “there were no significant differences in obstetric and fetal outcomes between the two groups.”

Diabetes Care 2009;32:996-1000.