Are complex carbohydrates useful in the diets of women with gestational diabetes?

This study examined whether blood glucose levels remain in the recommended range in women with gestational diabetes on a high complex carbohydrate and low fat diet.

Diets for women diagnosed with gestational diabetes generally involve reducing carbohydrate intake to 30-40% of total calorie intake. However, this can lead to an increase in fat intake, which increases the risk of having an infant with a high weight at birth.

Carbohydrates are energy present in food. There are two main forms of carbohydrates. Complex carbohydrates such as starch and cellulose are found in foods such as oatmeal and potatoes. Simple carbohydrates include white bread, white rice, candy and other sweet-tasting foods.

There are currently no definitive guidelines as to the ideal diet for women diagnosed with gestational diabetes. Often, the diet recommended will be low in carbohydrates but higher in fat. A high-fat diet can increase infant birth weight. A diet with high complex carbohydrates and low fat may reduce the risk of the infant having a high weight. However, it is unknown whether women on this diet can maintain blood glucose levels within the recommended range. 

This study aimed to determine whether women on a high complex carbohydrate diet (CCD) and low fat diet could maintain blood glucose levels within the recommended range.

This study involved 16 women with gestational diabetes. This study was performed at 31 weeks of gestation. Blood glucose levels were measured in women over a 12 day period. Over 12 days, the women received a high CCD with low fat (60% carbs/25% fat/15% protein) for 3 days, followed by a low CCD with higher fat (40% carbs/45% fat/15% protein) for 3 days. Women received a washout diet (50% carbs/35% fat/15% protein) for two days between the high and the low CCD.

Night-time blood glucose levels were similar with both diets. Average blood glucose levels were slightly higher in women on the high CCD diet (5.27 mmol/L) compared to the low CCD diet (5.04 mmol/L), but were still within the recommended range. The levels of free fatty acids (by-product of fat in the diet) in the blood were lower when women were on the high CCD. 

This study concluded that a diet of high complex carbohydrates and low fat intake did not significantly increase blood glucose levels compared to a low carbohydrate diet.

The sample size of 16 women was quite low and should ideally be higher. In addition, the study period was quite short (3 days on each diet). This study did not actually report the birth weights, so the infant outcome is not clear.

Consult your physician regarding dietary guidelines for women with gestational diabetes.