T2D is one of the fastest growing chronic diseases worldwide – this is thought to be due to the ever-growing number of people who are inactive and are becoming overweight or obese.
Preventing the transition from pre-diabetes to T2D is a major challenge in many countries. While several successful lifestyle interventions have been implemented in countries around the world, more research into an optimal preventive diet is still needed.
As part of the largest study of its kind, experts from around the world, including Professor Ian Macdonald and Dr Liz Simpson from the School of Life Sciences at the University of Nottingham, set up the PREVIEW Project (PREVention of diabetes through lifestyle Intervention and population studies in Europe around the World).
The aim of the study was to find out what the most effective lifestyle (including diet and physical exercise), was to prevent T2D in those who are at risk of developing the disease.
The main findings of the study are published in Diabetes, Obesity and Metabolism.
The large, multi-national clinical trial was designed to compare a high-protein-low-glycaemic index (GI) diet to a conventional moderate-protein-moderate-GI diet for diabetes prevention and weight maintenance in people at risk. Furthermore, the effect of combining either diets with high-intensity or moderate-intensity physical activity was investigated.
A three-year multi-centre, randomised controlled trial was conducted in eight countries (the UK, Denmark, Finland, the Netherlands, Spain, Bulgaria, Australia and New Zealand), starting with an eight-week weight-reduction phase followed by a three-year weight-maintenance phase.
In the first phase participants had to achieve a weight loss of 8% or more using total meal replacements (kindly donated by the Cambridge Weight Plan ®). In total 2,326 adults aged 25-70 years, with overweight or obesity and pre-diabetes were enrolled.
The most important finding in PREVIEW was the low incidence of diabetes in all groups at the end of the study. The total number of cases was only 62, giving a cumulative incidence of only one per 100 person-years, compared with ~five per 100 person-years in the diet arm of the Diabetes Prevention Program* in the USA.
There were no differences between the two diets or the two physical activity programs, although fewer participants in the high protein groups achieved normal glucose status. With such a low incidence of diabetes, the study did not have the ability to detect any difference between the diet or physical activity arms. It is also important to note that there was no untreated control group to compare with the two apparently healthy diets.
Our findings did not show that one diet or exercise program was superior to the other and that combining an increase in physical activity with having a healthy diet reduced the risk of developing diabetes.”
“It is tempting to suggest that the rapid weight loss in phase 1 was the main contributor to the findings, but further work is needed to confirm this. Maintaining the target protein and GI over three years was not easy, but the overall protocol combining weight loss, healthy eating, behavior change, and physical activity was more successful in reducing the risk of T2D than any previous diabetes prevention study. This represents an important clinical advance.”
A full copy of the study can be found here.