PLOS Medicine Senior Research Editor Clare Garvey on week three of the Special Issue on Preventing Diabetes
Week three of the PLOS Medicine Special Issue on Preventing Diabetes brings a trio of research papers that focus on diet in large population, as well as a study looking at how diabetes develops in obese adults, and a Perspective on improving screening and prevention for people at high risk of developing diabetes.
What makes up a healthy diet, and what are the costs? Annalijn I Conklin (University of California Los Angeles, USA) and colleagues colleagues present a fascinating study that considers both questions. Conklin and colleagues first analysed diet diversity, finding that greater diet diversity was associated with 30% lower risk of developing diabetes. Their study included over 23, 000 participants from the population based EPIC- Norfolk cohort who completed a diet diversity questionnaire and were followed up over the next 10 years to monitor incidence of diabetes. The authors went on to analyse the monetary cost of a more diverse diet and hence lowered diabetes risk, finding that the cost of the diversified diet—including the 5 diet groups of dairy, fruits, vegetables, meat (and alternatives) and grain—was 18% higher compared to those reporting a limited diversity in diet. Once again, we see a study highlighting disparities for diet and diabetes management for different socio economic groups. Policies or approaches should focus on how to best support lower socio-economic groups to achieve a healthy mixed diet.
In the first of 2 studies looking at the effects of types of fat on incidence of diabetes, Fumiaki Imamura (Institute of Metabolic Science, University of Cambridge) and colleagues report the effects on blood glucose control, insulin sensitivity and an ability to produce insulin in response to eating meals with varying levels of different fat types. In their systematic analysis of 4660 participants from 102 randomised controlled trials, the authors reveal how a replacing a high carbohydrate diet is with one higher in saturated fat (but the same total calories) has no influence on blood glucose control, while substituting carbohydrate calories with calories frim mono- or poly-unsaturated fat has a beneficial effect. The magnitude of improvement in blood glucose control in response to 5% of energy increase of these healthy fats is estimated to reduce diabetes incidence by 22% and cardiovascular disease by 6.8%, highlighting the benefits of a diet rich in seeds, fish and avocados instead of animal fats or refined grains.
In a large cohort study including over 27,000 individuals from 8 countries, Nita Gandhi Forouhi, (Cambridge University, United Kingdom) and colleagues also found that not all fats are good fats. Forouhi and colleagues present analysis comparing blood samples from over 12, 000 who subsequently developed diabetes with over 15,000 participants who did not develop diabetes. Forouhi and colleagues measured blood levels of different types of polyunsaturated fats and found that higher levels of omega-3 fatty acid and omega-6 linoleic acid were associated with lower diabetes risk, while omega-6 came with a higher risk of diabetes. Those at risk of diabetes might want to opt for plant- or fish-derived polyunsaturated fats.
In the fourth research paper this week, Klodian Dhana and colleagues from the University Medical Center Rotterdam, the Netherlands provide key insights into life expectancy for adults aged over 55 years old who are either obese, overweight or of normal weight. They report in their large epidemiologic analysis how obese adults develop diabetes earlier in life compared to normal weight counterparts. Furthermore, the number of years that one can expect to live with diabetes is greater if obese. Interestingly, in their analysis of over 6000 participants, there was no statistical difference in total life expectancy for those who were obese. Nevertheless, the increased years of managing a disease is likely to add pressure to healthcare systems as associated co-morbidities arise. As the authors say, understanding this relationship may “be important to clinicians, patients, and policy makers in tackling the next stages of obesity epidemics.” All of these studies highlight the importance of choosing a healthy and balanced diet to avoid diabetes and obesity. Clearly policy makers and governments need to support individuals and groups to educate and promote healthy choices. In America alone, obesity runs at over 40% for women and 35% for men. The public health ‘time-bomb’ is just around the corner unless urgent action is taken on diet education.
Finally, in the Perspective article Screening for Dysglycemia: Connecting Supply and Demand to Slow Diabetes Incidence, Mohammed Ali and Venkat Narayan (both from Emory University, United States) discuss the importance of and challenges to identifying people at high risk for diabetes and providing them with preventative interventions. While calling for improved screening guidelines and delivery of targeted preventative interventions, they also note that this goal “should be considered complementary to—and not mutually exclusive with—society-level population-based policies that need to advance in terms of rigor of the evidence base.”
Only one more week in the PLOS Medicine Special Issue on Preventing Diabetes! Check with Speaking of Medicine for the final update next Tuesday. And on Wednesday, July 27, join Special Issue Guest Editor Nick Wareham for his PLOS Science Wednesday AMA on redditscience (/r/science). He’ll be tackling the topic of preventing diabetes and answering questions about the entire Special Issue.
Clare Garvey, PhD, is the Senior Research Editor at PLOS Medicine.
Featured image credit: Rob Pongsajapan, Flickr