Low-carb diet may eliminate need for drugs in type 2 diabetes

This randomized controlled trial included 57 Black and white adult men and women aged 35 to 65 with “mild” type 2 diabetes.

They had a hemoglobin A1c (HbA1c) of less than or equal to 8.0% and a body mass index (BMI) between 25 and 50.

Participants received their type 2 diabetes diagnosis within the previous 10 years and were being treated with diet or medications but were not using insulin.

Researchers had participants discontinue their medications one or two weeks before baseline testing. Then, they assigned participants to one of two diets for 12 weeks:

• a reduced carbohydrate diet with about 9% carbohydrates and 65% fat
• a higher carbohydrate diet with about 55% carbohydrates and 20% fat.

They wanted to see if a lower-carb diet would improve participants’ beta-cell response to sugar (glucose) compared to a higher-carb diet.

Both diets were designed by a registered dietitian to be “eucaloric,” meaning that the diets provided the number of calories each participant needed to maintain their body weight.

The study provided participants with daily meals, detailed meal plan instructions, and weekly meetings with the registered dietitian.

The researchers used hyperglycemic clamp and oral glucose tolerance tests to examine the participant’s beta-cell function and insulin release at the beginning and end of the 12-week diet period.

During the dietary intervention, two participants from the higher carb group and one from the lower carb group resumed their metformin medication, and their data was included in the results.

After 12 weeks, the researchers observed significant improvements in beta-cell function and insulin release among participants on the low-carb diet compared to those on the higher-carb diet.

Specifically, they discovered that individuals on a low-carb diet experienced improvements in initial (rapid) and maximal beta-cell responses that were twofold and 22% greater, respectively, compared to those on a high-carb diet.

The oral glucose tolerance test results showed that after 12 weeks, the low-carb diet improved insulin’s effect on blood glucose levels by 32%.

Among all groups, Black adults following a low-carbohydrate diet showed a 110% greater improvement in rapid beta-cell response than those on a high-carbohydrate diet. This effect was not observed in white adults.

Conversely, white adults experienced a 48% greater improvement in maximal beta-cell response than those on a high-carbohydrate diet, a difference not observed in Black adults.

The study’s authors propose that the varying responses to the diet intervention observed between races might be partially due to biological differences in beta-cell function.

Black adults may exhibit a higher immediate insulin response to glucose compared to white adults, even when their levels of insulin sensitivity are equivalent.

They concluded that “with the caveat that [carbohydrate restriction] may be difficult for some patients, such a diet may allow patients with mild [type 2 diabetes] to discontinue medication and enjoy eating meals and snacks that meet their energy needs while improving beta-cell function, an outcome that cannot be achieved with medication.”

The study found that insulin sensitivity, or how effectively the body uses insulin, didn’t change much with the diet interventions. So, it’s unlikely that changes in insulin sensitivity were the reason for the improvements in beta-cell response specific to the low carbohydrate diet.

In other words, the improved beta-cell responses were likely due to something other than changes in insulin sensitivity.

More research is needed, but Medical News Today spoke with Thomas M. Holland, MD, MS, a physician-scientist and assistant professor at the RUSH Institute for Healthy Aging, RUSH University, College of Health Sciences, who was not involved in the study, to gain a better understanding of how a low-carb diet might improve beta-cell function.

He explained that:

“A carbohydrate-restricted diet can improve [pancreatic] beta islet-cell function in people with mild type 2 diabetes by reducing the strain on the beta-cells to produce insulin. This improvement is likely due to less glucose (from carbohydrates) entering the bloodstream, which reduces the demand on beta-cells for insulin secretion, potentially reversing some of the beta-cell dysfunction caused by glucose toxicity.”

“While this benefit is more pronounced in those with mild diabetes, it may still help individuals with prediabetes [with an HbA1c of about 5.7%-6.4%] or even those with more advanced diabetes, though the extent of improvement might vary person to person,” Holland added.

Holland highlighted that “a carbohydrate-restricted diet can be beneficial for managing type 2 diabetes, but adherence, particularly among older adults, can be challenging.”

To make a low-carb diet more sustainable, he recommended:

• incorporating flexibility in carb intake while prioritizing whole, unprocessed or minimally processed foods rich in fiber and nutrients
• adding variety and making the diet enjoyable
• monitoring blood sugar levels regularly, especially when adjusting or reducing medications under a healthcare provider’s guidance
• consulting with a healthcare provider is to ensure the diet aligns with individual health needs.

“While a ketogenic [very low carbohydrate] diet may be effective if followed correctly, under the guidance of a dietitian or physician, a significant concern is the potential for rebound effects when reintroducing carbohydrates,” Holland warned.

He explained that these rebound effects can cause “substantial weight gain and strain on the beta islet-cells to ensure appropriate insulin production,” which may lead to negative health outcomes.

MNT also spoke withSheri Gaw, RDN, CDCES, a registered dietitian, certified diabetes care and education specialist, and owner of The Plant Strong Dietitian, who was also not involved in the study.

She similarly advises choosing high-fiber, low-carb foods to make low-carb diets easier to sustain, as “fiber helps to slow down digestion and increase satiety.”

She recommended foods such as:

• broccoli
• mushrooms
• leafy greens
• cauliflower
• chia seeds
• walnuts
• ground flaxseed
• almonds.

“A carb-restricted diet may work for some people with type 2 diabetes, but not all,” Gaw said, emphasizing that there is no one-size-fits-all approach.

For those for whom a low-carb diet is not ideal, Holland highlighted other science-backed diets and lifestyle changes that may improve beta-cell function:

“Alternative diets that can improve beta-cell function include the Mediterranean and MIND diets, which are rich in healthy fats and low in refined carbohydrates — like sugar, flour, and other [refined] grains, and intermittent fasting, which can reduce glucose levels and improve insulin sensitivity. Lifestyle changes like regular physical activity, weight management, mindfulness and stress reduction have also shown evidence of improving beta-cell function and overall metabolic health.”