PREVIEW: Intensive weight loss, behavior change prevents conversion to type 2 diabetes
SAN FRANCISCO — An initial weight loss of at least 8% over 8 weeks using meal replacement products followed by a lifestyle intervention of diet and physical activity markedly reduced the number of new cases of type 2 diabetes in a cohort of adults with prediabetes, according to findings from the PREVIEW study presented here.
In an international, randomized controlled trial comparing two diet and two weight-management programs, researchers observed a low, similar rate of progression to type 2 diabetes among people with prediabetes who had initially lost weight on a low-calorie diet, regardless of the diet or exercise plan followed thereafter.
“We have known for many years that lifestyle change can reduce the risk of prediabetes converting to type 2 diabetes,” Ian Macdonald, PhD, professor of metabolic physiology at the University of Nottingham, United Kingdom, and a principal investigator in the PREVIEW trial, told Endocrine Today before presenting the findings at the American Diabetes Association Scientific Sessions. “This study shows a highly effective strategy involves initial meal replacement to achieve weight loss followed by a 3-year period of weight maintenance.”
Initial weight loss, sustained maintenance
Macdonald and colleagues analyzed data from 2,223 adults with prediabetes recruited from centers in Australia, Bulgaria, Denmark, Finland, New Zealand, Spain, the Netherlands and the United Kingdom, beginning in 2013. For the first phase of the 36-month intervention, participants were assigned to a low-calorie diet via meal replacement (800 kcal per day) for 2 months to achieve rapid weight reduction. For the second phase, participants were assigned to one of two dietary approaches: a high-protein/low-glycemic index diet or a moderate-protein/moderate-glycemic index diet. Researchers asked participants of both diet groups to increase their physical activity to high intensity for 75 minutes per week or moderate intensity for 150 minutes per week, for a total of four treatment arms. Randomization was stratified by sex and age group (aged 25 to 45 years, aged 46 to 54 years and aged 55 to 70 years) to ensure an even distribution across the four intervention arms.
Initial meetings with dietitians and exercise specialists were conducted at 2- to 4-week intervals, decreasing to every 6 months for the second year and to every 12 months by year 3, Macdonald said. Researchers assessed the effect of a high-protein, low-glycemic index diet vs. a moderate-protein, moderate-glycemic index diet in combination with moderate- or high-intensity physical activity on the incidence of type 2 diabetes over 3 years.
“To start with, there were lots of fairly intensive visits to see the dietitian, the exercise specialist and so on,” Macdonald said while presenting the findings Saturday. “As the trial proceeded, those intervals widened because this was real life in a health system that can’t afford to see you every 2 weeks for the rest of your life. That undoubtedly was one of the reasons why people started to drop out.”
Behavior change key
Within the cohort, 2,202 participants lost 8% body weight during the low-calorie diet phase, Macdonald said. When the study concluded in January, 962 participants remained. Of those, 62 participants progressed to type 2 diabetes, for a cumulative incidence rate of 4% over 3 years. There were no between-arm differences between the two diets or the two physical activity programs, Macdonald said.
“It was estimated from the literature that with such high-risk patients, 21% would develop type 2 diabetes over 3 years,” Macdonald said. “The moderate-protein/moderate-glycemic index diet was predicted to reduce the incidence of type 2 diabetes to 15.8%, while the high-protein/low-[glycemic index] diet was predicted to reduce the incidence to 10.5% over 3 years. In fact, there was no difference between the two diets; however, the overall incidence of type 2 diabetes in both groups combined was 4% over 3 years.”
Macdonald said the findings suggest the initial period of weight loss is likely “a major contributor” to the observed reduced risk for type 2 diabetes.
“The details of the subsequent weight-maintenance program are less important, provided it is delivered with effective behavior-change strategies,” Macdonald said.
Researchers noted that the overall dropout rate was high; more than 50% of participants withdrew before 3 years.
“Clinically, the challenge will be to deliver this type of program in primary care/family practice/community settings, and this will require physicians, nurses and other health professionals being trained to deliver the diet and physical activity advice together with the behavior-change techniques,” Macdonald said. “The other major challenge is to find ways of keeping people with prediabetes participating in such lifestyle modification and risk reduction strategies. A 50% dropout rate in 3 years is very disappointing, and more work is needed to find ways of keeping such high-risk patients in a prevention program.” – by Regina Schaffer
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.
Disclosures: Macdonald reports he serves on advisory boards for Mars, Nestlé, Novozymes and Zaluvida, and has received speaking fees from the British Nutrition Foundation and the Nutrition Society.