In a randomized trial, declines in HbA1c over 6 months were “modest” but warrant further study and longer follow-up.
A low-carbohydrate diet may help lower hemoglobin A1c in patients with prediabetes or mild diabetes who are not already on medication, a small, randomized study suggests.
“There’s good evidence that in people with type 2 diabetes a low-carb diet can reduce blood sugar levels. But there’s much less known and understood about people in that [lower] range and how low carb could affect their blood sugar,” said Kirsten S. Dorans, ScD (Tulane University School of Public Health and Tropical Medicine, New Orleans, LA), lead author of the study published this week in JAMA Network Open.
Among the 150 participants randomized to fewer than 60 g of carbs per day, or their usual diet, a greater reduction from baseline HbA1c levels was achieved in the low-carb group at 6 months. Dorans and colleagues say the mean decrease of 0.23%, which was significant (P < 0.001), was also “modest” and accompanied by a lower calorie intake and greater weight loss.
“The key message to take away here is that a low-carb diet, if it’s maintained, may be a useful approach to preventing and treating type 2 diabetes, but more research is needed,” she added.
Interest in low-carb diets for weight loss and cardiometabolic diseases date back decades, but trials thus far have produced mixed results. Recent diabetes screening recommendations from the US Preventive Services Task Force advise clinicians to refer patients with prediabetes to preventive interventions, including lifestyle changes, diet and exercise leading to weight loss, noting that about a third of those who are prediabetic aren’t even aware of it.
Differences Beyond Just HbA1c
Patients randomized into the study (mean age 59 years; 72% female; 59% Black) had untreated HbA1c between 6.0% and 6.9% (42 to 52 mmol/mol). The low-carb group (n = 75) received behavioral counseling and key supplemental food, including nuts and olive oil, to improve odds of compliance. For the first 3 months, the low-carb group was asked to limit daily carbohydrate intake to < 40 g/day, and then from months 4…