Women with gestational diabetes eating fewer than 120 grams of carbohydrates daily at about 29 weeks of gestation spent 6.8 percentage points less time with elevated glucose than those eating 175 grams or more, according to a secondary analysis of the DiGest trial published in Diabetes Care.
Low-Carb Diets Lower Glucose Levels
Researchers examined data from 215 women with a singleton pregnancy and a body mass index of 25 or higher to evaluate how dietary carbohydrate levels affect glycaemia. The analysis appeared online on October 20, 2026.
The analysis was led by Ehtasham Ahmad of University Hospitals of Leicester NHS Trust and Leicester General Hospital alongside Sarah Dib of the Leicester National Institute for Health and Care Research Biomedical Research Centre at University of Leicester.
Participants completed at least one 24-hour dietary recall and wore a masked continuous glucose monitor about one week before starting trial diets at roughly 29 weeks of gestation.
The study divided participants into three self-reported baseline carbohydrate intake groups: standard at 175 grams or more per day, low ranging from 120 to under 175 grams per day, and very low at under 120 grams per day. Women in the very low intake group spent 6.8 percentage points less time with glucose above 120 milligrams per deciliter compared with the standard intake group. Diets providing less than 35 percent of energy from carbohydrates showed similar outcomes, achieving 6.9 percentage points less time above that threshold alongside lower overall glucose variability and no increase in time below the 63 milligrams per deciliter target range.
Investigators noted that the observed glycemic benefits were partially driven by lower overall calorie intake. Our findings suggest that overall dietary quality matters; the benefits associated with a low-carbohydrate diet were driven, at least partially, by the lower calorie intake, suggesting that a modest energy restriction with modest carbohydrate restriction is likely to be beneficial in women with GDM and BMI ≥ 25 kg/m2,
the authors wrote.
Ehtasham Ahmad and Sarah Dib, Study Authors.
Low Carbohydrate Intake Reduces Essential Nutrient Consumption
While restricted carbohydrate intake lowered glucose levels, it also reduced the consumption of several essential nutrients. Dietary fiber intake dropped across the groups, averaging 17.5 grams per day in the standard group, 14.1 grams per day in the low group, and 9.7 grams per day in the very low group. Lower carbohydrate consumption also tracked with reduced intakes of vitamin E, calcium, magnesium, potassium, zinc, and B vitamins including thiamine, riboflavin, niacin, biotin, and vitamins B6 and B12.
Infants born to mothers consuming less than 120 grams of carbohydrates daily had lower birth weight centiles than those in the standard group, with an adjusted coefficient of minus 9.6 centiles. However, the rates of large-for-gestational-age and small-for-gestational-age birth weights did not display statistically significant differences between the cohorts.
MedlinePlus medical guidance outlines daily nutritional management for gestational diabetes, advising patients to consume three small- to moderate-sized meals and one or more snacks each day without skipping. Official recommendations encourage plenty of whole fruits and vegetables, moderate amounts of lean proteins and healthy fats, and moderate amounts of whole grains such as bread, cereal, pasta, and rice alongside starchy vegetables like corn and peas. The guidance also advises limiting fatty foods, avoiding simple carbohydrates that cause rapid blood sugar spikes, and targeting four daily servings of low-fat or nonfat dairy products.