In a comparison of two different diet and two different weight management programs, results of the international PREVIEW intervention study found a low, similar rate of progression to type 2 diabetes (T2D) among people with prediabetes who had initially lost weight on a low-calorie diet (LCD), according to a symposium presentation today titled “PREVIEW Study Results—Prevention of Diabetes through Lifestyle Intervention and Population Studies Around the World” at the American Diabetes Association’s® (ADA’s) 79th Scientific Sessions® in San Francisco. The study showed no difference between either of the post-weight loss diet or exercise-management programs, with the participants who had initially lost weight in all groups having a three-year incidence rate of T2D of 4%, which was much lower than anticipated.

In order to identify the most effective lifestyle patterns for the prevention of T2D in a population of people who have prediabetes and are overweight, researchers around the globe began “PREVention of diabetes through lifestyle Intervention and populations studies in Europe and around the World” (PREVIEW). The study’s aim was to determine the effects and interactions of different types of diets and different exercise regimens on the development of new cases of T2D in patients with prediabetes.

“Further work is needed to explore the reasons for such successful prevention of T2D, however, it is likely that the initial weight loss combined with thorough education and support in the components in either nutrition plan, in addition to a physical activity program, led to successful lifestyle change and maintenance of at least some of the initial weight loss in most of the people completing the trial,” said one of the lead investigators Ian Macdonald, BSc, PhD, professor of metabolic physiology at the University of Nottingham. “The inclusion of an initial period of a low-calorie diet achieving significant weight loss, preceding a well-structured and effectively delivered weight maintenance program, may be a major feature of future diabetes prevention programs.”

PREVIEW is, to-date, the largest multi-national trial to address T2D prevention in adults with prediabetes through nutrition and exercise. The study began in 2013 and enrolled 2,223 participants using intervention centers in Denmark, Finland, the United Kingdom, the Netherlands, Spain, Bulgaria, Australia and New Zealand. The 36-month intervention consisted of two phases: a two-month period of rapid weight reduction achieved using an LCD (800 kcal/day), followed by a 34-month randomized diet and exercise phase for weight loss maintenance consisting of four treatment arms. The impact of a high-protein, low-glycemic index (GI) vs. moderate protein, moderate-GI diet in combination with moderate or high-intensity physical activity on the incidence of T2D and the related clinical end-points were investigated.

Participants were recruited for screening on the basis of their Body Mass Index and other components of the Finnish Diabetes Risk Score. At screening, fasting plasma glucose and 2-hour post OGTT plasma glucose were used to identify those with impaired fasting and/or post OGTT glucose values, which was defined as pre-diabetes and at a high risk of developing T2D.Upon confirmation of eligibility, participants were enrolled into the trial and randomized to one of the four treatment groups. Randomization was stratified by gender and age group (25–45, 46–54 and 55–70 years of age) and sequentially assigned from each stratum to different interventions, securing an even distribution of gender and age group over the four intervention arms in each center.

Researchers conducted Clinical Investigation Days (CID) through the intervention from CID1 (baseline) to CID7 (trial end) using data collected from blood tests, urine samples, diaries, body composition assessments and accelerometers. Adverse and serious adverse events and concomitant medications were recorded. In addition, instructors led a total of 17 group visits throughout the trial to support lifestyle modification including nutrition counseling and physical activity. The CID assessments and group visits were conducted within university settings or associated clinics. Participants followed the diet and physical activity counseling advice in a “real-life” setting without daily supervision from researchers.
The primary hypothesis (based on the DiOGenes study) was a higher-protein (HP) diet with low glycemic index (LGI) carbohydrates combined with an initial period of weight loss would be more effective than a moderate protein and moderate glycemic index (GI) diet combined with an initial period of weight loss (based on the Finnish Diabetes Prevention Study and the Diabetes Prevention Program studies). The study also set out to examine whether high-intensity, shorter duration physical activity was superior to moderate-intensity, longer duration physical activity. PREVIEW researchers estimated that the LCD followed by the standard dietary approach combined with either physical activity program would lead to a three-year incidence of T2D of 15.8%, and that the HP-LGI maintenance diet would reduce this incidence to 10.5%.

Of the 2,223 originally enrolled, 2,202 successfully lost 8% of weight during the LCD, and in January 2019 when the study ended, 962 still remained in the study at 36 months. The total number of cases of T2D was 62, giving a cumulative incidence rate of T2D of 4% over the three years. There were no differences between the two diets or the two physical activity programs. The main funding for this study came from an EU FP7 Grant.

“It is tempting to suggest that the initial weight loss on the low-calorie diet was a main contributor to the findings, but further work is needed to confirm this,” said Dr. Macdonald. “The design of the study was such that those who dropped out could not be followed up at 3 years, so it is not known how many of the original 2,223 people had developed type 2 diabetes after 36 months. These results illustrate, though, that combining an initial low-calorie diet to establish significant weight loss followed by a maintenance diet and physical activity program with evidence-based advice on achieving behavior change can achieve longer term maintenance of weight loss and reduce the risk of developing type 2 diabetes.”

To speak with Dr. Macdonald please contact the ADA Press Office on-site at San Francisco’s Moscone Convention Center on June 7-11, by phone at 415-978-3606 or by email at SciSessionsPress@diabetes.org

The American Diabetes Association’s 79th Scientific Sessions, the world’s largest scientific meeting focused on diabetes research, prevention and care, will be held June 7-11, 2019, at the Moscone Center in San Francisco, California. Nearly 15,000 leading physicians, scientists, health care professionals and industry representatives from around the world are expected to convene at the Scientific Sessions to unveil cutting-edge research, treatment recommendations and advances toward a cure for diabetes. During the five-day meeting, attendees will receive exclusive access to more than 850 presentations and 2,000 original research presentations, participate in provocative and engaging exchanges with leading diabetes experts, and can earn Continuing Medical Education (CME) or Continuing Education (CE) credits for educational sessions. The program is grouped into eight thematic areas: Acute and Chronic Complications; Behavioral Medicine, Clinical Nutrition, Education and Exercise; Clinical Diabetes/Therapeutics; Epidemiology/Genetics; Immunology/Transplantation; Insulin Action/Molecular Metabolism; Integrated Physiology/Obesity; and Islet Biology/Insulin Secretion. Gretchen Youssef, MS, RDN, CDE, President of Health Care and Education, will deliver her address, “It’s All About Access!,” on Saturday, June 8, and Louis H. Philipson, MD, PhD, FACP, President of Medicine and Science, will address attendees on Sunday, June 9. Join the Scientific Sessions conversation on social media using #ADA2019.

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