Can diet and exercise reverse type 2 diabetes? What a new study found

By Katia Hetter, CNN

(CNN) — While an estimated 38 million Americans have type 2 diabetes, the condition is increasingly being diagnosed in younger adults. Without treatment, they face decades of elevated risk for complications like heart disease and kidney failure.

A recent study published October 1 in the journal The Lancet Regional Health – Americas investigated whether a combination of intensive weight loss and structured exercise could put early-onset type 2 diabetes into remission.

Researchers enrolled 96 adults ages 18 to 45 who had obesity and had been diagnosed with type 2 diabetes within the previous six years. The participants’ average age was about 38, and they had lived with diabetes for an average of just over two years. The small clinical trial was conducted in Canada and the United Kingdom.

To help understand the findings and what they mean for diabetes treatment, I spoke with CNN wellness expert Dr. Leana Wen. Wen is an emergency physician and clinical associate professor at George Washington University. She previously was Baltimore’s health commissioner.

CNN: Why is early-onset type 2 diabetes particularly concerning?

Dr. Leana Wen: Early-onset type 2 diabetes refers to diabetes diagnosed by age 45. It tends to progress more rapidly than diabetes diagnosed later in life, with faster progression and a higher risk of complications.

Someone diagnosed at age 30 could live with diabetes for decades. Over that time, elevated blood sugar can damage blood vessels, nerves, kidneys and eyes. Younger adults with type 2 diabetes also face an increased risk of cardiovascular disease and premature death.

Substantial weight loss can put type 2 diabetes into remission, previous research has shown, but most of these trials have focused on older adults. In this study, the researchers wanted to know whether this approach could work for younger patients, whose disease can be more aggressive. The team also wanted to test whether adding supervised exercise that included strength training could preserve muscle during rapid weight loss.

CNN: What did the study find?

Wen: Participants were randomly assigned to either an intensive diet and exercise program or their usual medical care, meaning they continued treatment with their healthcare provider. After six months, 54% of participants in the intervention group achieved diabetes remission, compared with just 4% receiving usual care.

Remission was defined as a hemoglobin A1c level below 6.5%, the threshold for diagnosing diabetes, without glucose-lowering medication for at least three months. (Hemoglobin A1c reflects average blood sugar measurement over a period of time and is a standard measure of diabetes diagnosis and treatment effectiveness.)

The intervention group’s participants also experienced substantial reductions in body fat, losing approximately 16.5 pounds (7.5 kilograms) more compared with those receiving usual care. They also increased their cardiorespiratory fitness, demonstrating lower resting heart rate and improved exercise capacity.

During the first 12 weeks, those in the intervention group followed a supervised diet that restricted calorie intake to 800 to 900 calories daily. For the first two weeks, these individuals consumed only meal replacements, then incorporated one regular meal daily while maintaining the calorie target. Beginning in the third week, the intervention group’s participants attended two exercise sessions weekly that combined aerobic activity with resistance training using weights or exercise machines. They also completed a third aerobic exercise session independently each week.

During the final 12 weeks, participants gradually returned to regular food with the goal of maintaining weight loss. They continued to work out independently and received ongoing support from dietitians and exercise specialists. Physicians monitored the participants’ blood sugar and blood pressure throughout the program and adjusted medications as needed.

People looking to replicate these results must understand how intensive the intervention was. The calorie limitation was severe and would be difficult for many people to follow safely. The exercise sessions were also demanding, and only 40% of participants met all the study’s criteria for adherence to the program. The study took place at three specialized centers with regular support from physicians, dietitians and exercise specialists. We do not know whether similar results could be achieved in routine clinical practice, where people may not have access to these resources.

CNN: What should people with type 2 diabetes do if they want to try reversing diabetes with diet and exercise?

Wen: I would start with a conversation with your clinician about whether remission is a realistic goal and what approach would be safe.

In particular, the low-calorie diet used in this study should not be attempted without very close medical supervision. People taking insulin or oral medications called sulfonylureas can develop dangerously low blood sugar when they sharply reduce food intake. Clinicians may need to adjust these and other prescription medications if someone changes their calorie intake.

A less restrictive approach can still produce significant improvements. People can work with a dietitian to eat a more nutritious diet, for instance by reducing sugary beverages and refined carbohydrates and prioritizing vegetables and fiber- and protein-rich foods.

For physical activity, work toward the recommended 150 minutes of moderate-intensity aerobic exercise weekly. Add resistance training at least twice weekly, with exercises targeting major muscle groups. Such changes can slow the progression of diabetes and prevent complications, even if they do not reverse it.

CNN: Why did the researchers emphasize strength training?

Wen: Muscle plays a major role in regulating blood sugar. After we eat, insulin helps move glucose from the bloodstream into muscle cells, where it can be used for energy or stored. In people with type 2 diabetes, insulin resistance makes this process less effective. Exercise helps muscles take up glucose and improves their sensitivity to insulin, which can lead to better regulation of blood sugar levels.

A consistent strength training routine has another important benefit: The activity helps preserve muscle during weight loss. When people lose substantial amounts of weight, they typically lose both fat and muscle. This loss of muscle mass may pose particular problems for people with type 2 diabetes, who are already at increased risk of impaired muscle function and premature frailty. Preserving muscle can help maintain physical strength and metabolic health.

In this study, participants in the intervention group lost substantial amounts of fat without significantly greater loss of muscle mass compared with those receiving usual care. Another notable finding is that those in the intensive intervention group improved their grip strength by approximately 8%, suggesting that their muscles became stronger even as they lost weight. These findings support recommendations to incorporate resistance training alongside aerobic exercise, especially when there is such rapid weight loss.

CNN: What are other limitations of this study?

Wen: First, this was a relatively small trial — and the participants were all younger adults with obesity and relatively recent diabetes diagnoses. Notably, researchers excluded people receiving insulin treatment and those with certain medical complications, including cardiovascular disease and significant kidney disease. We cannot assume that the same remission rates would apply to older adults, people who have lived with diabetes for decades or those with more advanced disease.

Second, the study compared a combined diet and exercise program with usual care but did not include a group that followed the same diet without supervised exercise. We therefore cannot determine how much additional benefit came from exercise, or whether the remission rate would have been similar with dietary changes alone. Participants in the intervention group also received substantially more attention from health professionals than those receiving usual care, which could have influenced their results.

Finally, researchers followed participants for only six months. Remission as measured during this period does not mean diabetes has been reversed permanently and cured. Blood sugar can rise again, particularly if someone regains weight or their pancreas loses more of its ability to produce insulin. Longer-term research is needed to determine how many participants can maintain remission over several years.

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