CAN A WHOLE‑FOOD, PLANT‑BASED DIET PLUS EXERCISE INDUCE DIABETES REMISSION?

Interest is increasing in dietary and lifestyle interventions to achieve type 2 diabetes remission. In a recently published paper, researchers from Loma Linda University in the US conducted a randomised control trial comparing a whole food plant-based diet combined with moderate exercise, with standard medical care, in individuals living with type 2 diabetes in the Marshall Islands, which has the seventh-highest diabetes prevalence globally.

The study included 169 adults, aged 18-75 years with type 2 diabetes. They either had a HbA1c (glycated haemoglobin; a measure of average glucose levels over the past 3 months) of 8.0% or more, or were diagnosed with type 2 diabetes and were already taking blood glucose lowering medication. They had an average age of 54 years, Body Mass Index (BMI) of 29.8 kg/m2 and HbA1c of 10.4 %.

Participants were randomly allocated to one of two groups: 1) a whole food plant-based intervention with moderate exercise, or; 2) standard medical care. The intervention was for 24 weeks and measurements were taken at baseline and 2, 6, 12 and 24 weeks.

The plant based dietary intervention involved consuming a whole food plant-based diet with minimal animal products and exercising 30-60 minutes per day. During weeks 1–12, participants in this group received prepared meals (12 meals/week in the first 2 weeks, 2 meals/week from weeks 3-6 and 1 meal/week from weeks 7-12), attended group exercise sessions and received group instruction on healthy eating, cooking, exercise and managing stress. The intensity of support progressively decreased and during weeks 13–24, participants were instructed to follow the intervention on their own. They were asked to eat no animal products or refined carbohydrates in the first two weeks of the study, and after this they were instructed to consume 75–100% of energy from whole, unprocessed plant foods (vegetables, legumes, whole grains and fruit) and the remainder of their diet could include no more than 25% lightly processed foods, no more than 10% moderately processed foods and moderate-fat animal products and no more than 5% heavily processed foods and high-fat animal products.

The control group received glucose-lowering medication according to standard medical care and were asked to maintain their current diet and physical activity levels.

Primary outcomes focused on glycaemic management including HbA1c, fasting glucose, fasting insulin, HOMA-IR (a measure of insulin resistance), and diabetes medication use. Secondary outcomes included cardiovascular risk factors and cardiovascular medication use. Diabetes remission was defined as achieving a HbA1c of less than 6.5% (48 mmol/mol) after not using glucose-lowering medications for at least 3 months.

Compared to the standard medical care, the plant-based diet and exercise intervention resulted in:

• A significant reduction in HbA1c at weeks 6, 12 and 24.
• A significant reduction in fasting glucose at weeks 2, 6 and 12, but not 24.
• A significant reduction in fasting insulin at week 6 and HOMA-IR at weeks 2,6 and 12 in participants not taking insulin.
• A greater reduction in medication use: 63% of the intervention group participants reduced their glucose lowering medication compared to 24% in the standard medical care group.
• Higher rates of diabetes remission: 8% of the intervention group achieved diabetes remission compared to none in the standard medical care group. 23% of the intervention group with a baseline HbA1c below 9% achieved remission although this was not statistically different from the standard medical care group.
• A greater reduction in the use of cardiovascular medications (e.g., blood pressure or cholesterol lowering medications): 67% of the intervention group reduced their dose of one or more cardiovascular medications compared to only 15% of the standard medical care group.
• A modest reduction in body weight at all time points (2.7 kg more than the standard medical care group at 24 weeks) and a significant reduction in waist circumference at week 6, 12 and 24.
• Greater reductions in systolic and diastolic blood pressures in weeks 2 and 6, although these effects waned by weeks 12 and 24.
• A reduction in high sensitivity CRP (C-reactive protein – a marker of inflammation) at all time points.

Overall, the study found that a mostly whole-food, plant-based lifestyle intervention with moderate exercise is effective for improving blood glucose management, reducing the need for diabetes and cardiovascular medications, and can induce remission of type 2 diabetes in some individuals. This approach was also found to be more effective than standard medical care.

Because the intervention group had intensive instruction including education sessions, group exercise classes and the provision of some meals, it is difficult to determine how much of the improvement was related to the specific dietary and lifestyle changes made or the fact that they had more intensive support for making these lifestyle changes. The study also didn’t assess how well participants were following the dietary and exercise recommendations.

However, the findings show that significant improvements in blood glucose levels can occur rapidly, even without substantial weight loss. This suggests that the benefits are primarily due to changes in diet quality and physical activity, rather than weight loss. Participants may have lost body fat and gained muscle mass, but this wasn’t measured. The study also demonstrates that diabetes remission is possible through improving diet quality and increased physical activity, even in individuals who experience modest or no weight loss. This is an important finding, as remission in other trials has correlated closely with significant weight (in particular abdominal fat) reduction.

Like the findings of many other studies, some improvements in outcomes were attenuated as the intervention intensity decreased in later phases of the study. This highlights the importance of individuals with diabetes finding an eating and exercise plan they can sustain for the long term, to maintain any lifestyle-related improvements in diabetes management.