While low-carb diets are a common next step for someone diagnosed with the disease, people who are prediabetic or with diabetes not treated with medication don't need to wait to cut back and see benefits to their blood sugar levels.
"The key message is that a low-carbohydrate diet, if maintained, might be a useful approach for preventing and treating type 2 diabetes, though more research is needed," said lead author Kirsten Dorans. She's an assistant professor of epidemiology at Tulane University School of Public Health and Tropical Medicine in New Orleans.
For the study, the researchers studied two groups of 75 people each. In one, participants were assigned to a low-carb diet. The other ate as usual.
Six months later, the low-carb diet group had greater drops in hemoglobin A1C, which is a marker for blood sugar levels. That group also lost weight and had lower fasting blood sugar levels.
While the study doesn't prove that a low-carb diet prevents diabetes, it opens the door to further research on how to work through health risks of those with prediabetes and diabetes not treated by medication, Dorans said.
"We already know that a low-carbohydrate diet is one dietary approach used among people who have type 2 diabetes, but there is not as much evidence on effects of this diet on blood sugar in people with prediabetes," Dorans said in a university news release. "Future work could be done to see if this dietary approach may be an alternative approach for type 2 diabetes prevention."
Study participants' blood sugar ranged from prediabetic to diabetic levels. The low-carb group saw A1C levels drop 0.23% more than the usual diet group.
That is "modest but clinically relevant," Dorans said.
While fats comprised about half of the calories eaten by those in the low-carb group, they were mostly healthy monounsaturated and polyunsaturated fats found in foods like olive oil and nuts.
The findings were published Oct. 26 in JAMA Network Open.
About 37 million Americans have diabetes and 96 million have prediabetes. More than 80% of those with prediabetes don't know it, according to the U.S. Centers for Disease Control and Prevention.
Prediabetes puts someone at increased risk for developing type 2 diabetes, as well as heart attack or stroke.
Diabetes occurs when the body doesn't use insulin as it should and can't regulate blood sugar levels. About 90% of people who have the condition have type 2 diabetes. Symptoms can include blurred vision, numb hands and feet, and overall tiredness. It can lead to heart disease, vision loss and kidney disease.
The U.S. Centers for Disease Control and Prevention has more on diabetes.
SOURCE: Tulane University, news release, Oct. 26, 2022