PREVIEW Study Confirms Prevention of Type 2 Diabetes — ADA 2019

The PREVIEW study examined which lifestyle interventions make a difference in preventing prediabetes from progressing to type 2.

The results from the PREVIEW international study, comparing two different diets and two different physical activity programs having a three-year incidence rate of type 2 diabetes of 4%, was presented at the American Diabetes Association’s (ADA’s) 79th Scientific Sessions in San Francisco. A similar, low rate of progression to type 2 diabetes among the participants with prediabetes who had initially lost weight on a low- calorie diet showed no difference between either of the post-weight loss diet or exercise-management programs.

“For years we have known that lifestyle interventions can prevent the progression of type 2 diabetes in a population of people with prediabetes,” stated Ian Macdonald, PhD, one of the lead investigators in the PREVIEW trial, presenting the findings at the scientific session. “However, the methods behind successful prevention needed to be explored. In the participants that completed the trial, their initial weight loss with education and support in addition to nutrition plans and exercise-management programs led to successful lifestyle changes followed by a three-year period of weight maintenance.”

PREVIEW (PREVention of diabetes through lifestyle Intervention and populations studies in Europe and around the World) is the largest, to date, multinational trial that identifies the most effective diet and exercise activity to prevent type 2 diabetes in participants who have prediabetes and overweight. The study determined the effects of different types of diets and different intense exercise programs on the development of new cases of type 2 diabetes in participants with prediabetes. The study began in 2013 with 2,223 participants enrolled in the trial for 36 months in 2 phases: a two-month phase of rapid weight loss using a low-calorie diet (>800kcal/day), preceding a 34-month phase consisting of diet and physical activity for weight loss maintenance. At randomization, participants were chosen into 4 treatment arms: high protein, low-glycemic index (GI) diet plus moderate physical activity; high-protein, low-GI diet plus high-intensity physical activity; moderate protein, moderate-GI diet plus moderate physical activity; and moderate protein, moderate-GI diet plus high-intensity physical activity. The intervention centers were located in Australia, Bulgaria, Denmark, Finland, New Zealand, Spain, the Netherlands, and the United Kingdom.

Fasting blood glucose and two-hour post oral glucose tolerance test plasma glucose were taken at screening to identify those with prediabetes and high risk of developing type 2 diabetes. To ensure even distribution amongst the 4 treatment arms at each center, the randomization selections were arranged by gender and age group (25–45, 46–54 and 55–70 years of age). Clinical investigation days (CID) were conducted throughout the intervention, where anthropometry, blood tests, and questionnaires were performed and diet records, accelerometers, and 24-h urine samples were collected. A total of 17 group visits were held during the trial to help support lifestyle changes and counsel participants on diet and physical activity.

The study’s primary hypothesis was that a higher protein, low GI diet would show more benefit in preventing type 2 diabetes when compared with a moderate protein, moderate GI diet. PREVIEW researchers also hypothesized that high-intensity physical activity will be more effective compared to moderate-intensity physical activity. The primary endpoint of this study was to determine the incidence of type 2 diabetes in high vs. moderate protein diet measured over a 36-month intervention period. The researchers estimated that the low-calorie diet followed by the moderate-protein and moderate-GI diet combined with either physical activity program reduced the three-year incidence of type 2 diabetes by 15.8% and the high-protein and low-GI diet reduced the three-year incidence by 10.5%.

A total of 2,202 lost 8% of weight during the low-calorie diet. Out of the 962 participants remaining in the study, the total number of cases of type 2 diabetes was 62, concluding an incidence rate of 4% over the three years. No differences were shown between the two diets or the two physical activity programs.

McDonald admitted to the over 50% dropout rate being disappointing, but future studies should have more incentives being used for high risk patients with prediabetes to stay motivated. McDonald concluded with the suggestion that the main contributor to the findings was the initiation of the low-calorie diet.

Practice Pearls:

• The PREVIEW study showed a three-year incidence of 4% in the occurrence of type 2 diabetes in patients with prediabetes and overweight, by maintenance diet and exercise.
• Starting a low-calorie diet to establish weight loss followed by a maintenance diet and physical activity program can achieve longer term maintenance of weight loss and reduce the risk of developing type 2 diabetes.
• The over 50% dropout rate of the study shows the importance of coaching and support for patients who are committing to lifestyle changes.

References:

1. Fogelholm, Mikael, et al. “PREVIEW: Prevention of Diabetes through Lifestyle Intervention and Population Studies in Europe and around the World. Design, Methods, and Baseline Participant Description of an Adult Cohort Enrolled into a Three-Year Randomised Clinical Trial.” Nutrients, MDPI, 20 June 2017, www.ncbi.nlm.nih.gov/pmc/articles/PMC5490611/.
2.       Macdonald I. Prevention of diabetes through lifestyle intervention — results from the multicenter PREVIEW study. Presented at: American Diabetes Association 79th Scientific Sessions; June 7-11, 2019; San Francisco.

Maya Rudolph, Florida A&M University, College of Pharmacy & Pharmaceutical Sciences, PharmD Candidate

Reported at the American Diabetes Association 79th Scientific Sessions June, 2019