Large-scale analysis gathers empirical evidence on role of diet and exercise in type-2 diabetes prevention Diabetes is a costly disease – according to WHO, the direct health care costs of diabetes range from 2.5 % to 15 % of annual national health care budgets. This worrying trend calls for action and a need for a variety of innovative approaches. PREVIEW included both clinical and population studies to see exactly how diet and exercise interact. Health © Africa Studio, Shutterstock The EU-supported PREVIEW project gathered a cohort of well over 2 000 adults and about 130 adolescents from a range of international locations, to identify more efficient lifestyle interventions to prevent diabetes. The project’s primary goal was to identify the most efficient lifestyle pattern for the prevention of type-2 diabetes (T2D) in a population of pre-diabetic overweight or obese individuals. To reach their target, the project had to pre-screen over 15 000 people and screen, in person, over 5 000 to ensure they had pre-diabetes. Over 300 investigators were employed on PREVIEW at some stage over the 6 years the project lasted, including nutrition scientists, dietitians, exercise physiologists, research assistants, medical doctors, doctoral and post-doctoral candidates, and masters and undergraduate students. The team considered the role of diet and exercise on T2D. In the adult study, 79 % of those who started the two-month weight loss phase (consisting of total meal replacement products kindly donated by Cambridge®) lost at least 8 % of their body weight. On average they lost 11 % of their body weight. “This was a remarkable achievement and almost double that of previous diabetes prevention studies,” says Prof. Jennie Brand-Miller, in charge of project dissemination. On the basis of previous research, PREVIEW hypothesised that a diet based on a high protein intake in combination with carbohydrate foods with a lower glycaemic index (GI) would be superior to a conventional diet with moderate protein and a moderate GI. The researchers found they were both equally successful in terms of T2D prevention and prevention of weight regain. The project also undertook population studies, pooling epidemiological studies in 5 different nations and about 130 000 participants. Early findings indicate that higher protein intake (grams per kilogram per day) is associated with reduced incidence of pre-diabetes and diabetes. Exercise was also analysed for its role in reducing T2D. The project wanted to establish what duration, intensity and frequency led to the best results. “We set out to compare two exercise strategies: 1) a moderate-intensity regime consisting of 150 minutes a week equivalent to 30 minutes walking on five days each week; and 2) a high-intensity regime equivalent to 15 minutes of jogging on five days each week. Both strategies were successful, and there were no differences between the two exercise groups,” explains Prof. Brand-Miller. Such a wide-ranging study depended on close collaboration, and the team is very proud of how well the researchers worked together. “Our leader, Prof. Anne Raben, was an efficient, exacting project coordinator with a great sense of humour.” PREVIEW presented their first findings in a dedicated symposium at the European Association for the Study of Diabetes in Berlin in October 2018. “We’ll be presenting more findings at the American Diabetes Association Scientific Sessions in San Francisco in June this year. Currently, we are working hard to prepare the main paper for publication.” The project is also responsible for dozens of sub-studies and over 20 publications on the drawing board. These include studies on appetite and insulin resistance using brain imaging and liver fat through MRI techniques. The work continues. “We have investigated the effect of animal vs plant proteins on kidney function and glucose metabolism. We’ll be looking at the microbiome in faecal samples and the differences in the metabolome in urine, collected in a sub-sample of the participants,” Prof. Brand-Miller concludes. Analysis of the effects of sleep and stress on the rate of T2D and prevention of weight regain will be undertaken this year. PREVIEW has over 70 000 data points, so more interesting findings are still to come. Keywords PREVIEW, type-2 diabetes, glycaemic index, protein, body weight, diet and exercise, nutrition
