Simply reducing dietary carbohydrate content was not an effective way to forestall the need for insulin among women with gestational diabetes, a randomized trial showed.

The percentage of patients who were started on insulin was 54.7% both among those who ate a low-carbohydrate diet and among those who ate a diet with a normal level of carbohydrates (P=1.00), according to Didac Mauricio, MD, PhD, of the University of Lleida in Spain, and colleagues.

Pregnancy and neonatal outcomes were similar in the two groups as well, the researchers reported online in Diabetes Care.

“Therefore, the amount of carbohydrates [in] the diet may not be a key issue in future clinical recommendations on medical nutrition therapy of gestational diabetes,” they wrote.

“Additional randomized intervention studies that consider different populations and different strategies to modify glycemic load are warranted to assess the optimal [approach],” they wrote.

Medical nutrition therapy has formed the basis of treatment for gestational diabetes, and has been centered on modifying the amount and distribution of carbohydrates to maintain glycemic control without ketosis, according to the researchers.

In recent years, the therapy has been aimed primarily at modifying the glycemic index, but there is little evidence-based information on specific approaches to managing the condition.

The current study was a randomized controlled trial that included 152 women with gestational diabetes who were pregnant with a single child. The mean age of the participants was roughly 33.

The women were randomized to a low-carbohydrate diet in which 40% of calories came from carbohydrates or a control diet in which 55% of calories came from carbohydrates. Protein made up 20% of the total calories in both diets, whereas fat made up 40% of the low-carbohydrate diet and 25% of the control diet. The women had three meals and three snacks each day.

All of the women received a glucose meter and were told to self-test and record their levels. They also recorded their carbohydrate intake using 3-day food records.

Women were started on insulin if at least two blood glucose levels measured at the same time of day during a 1-week time period were above targets—5.3 mmol/L or less for fasting and preprandial glycemia and 7.8 mmol/L or less for 1-hour postprandial glycemia.

The researchers found no significant between-group differences in the percentage of women who started insulin, in the insulin dose, or in the time to starting insulin treatment.

That was despite significantly lower carbohydrate and starch consumption in the intervention group (P≤0.0001 for both).

There were also no differences between the groups in a range of obstetric and perinatal outcomes, including ketonuria, maternal weight gain (after accounting for time since randomization), maternal hypertension, use of cesarean delivery, gestational age at delivery, stillbirth, birth size for gestational age, macrosomia, and newborn hypoglycemia.

The authors acknowledged some limitations of the study, including the failure to obtain food records from all participants, the higher-than-expected dropout rate in the control group, and the lack of statistical power to assess the intervention’s effect on maternal weight gain.

The authors reported that they had no conflicts of interest.

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Primary source: Diabetes Care
Source reference: Moreno-Castilla C, “Low-carbohydrate diet for the treatment of gestational diabetes: a randomized controlled trial” Diabetes Care 2013; DOI: 10.2337/dc12-2714/-/DC1.