Abstract
Prevention of type 2 diabetes (T2D) is a great challenge worldwide. The aim of this evidence synthesis was to summarize the available evidence in order to update the European Association for the Study of Diabetes (EASD) clinical practice guidelines for nutrition therapy. We conducted a systematic review and, where appropriate, meta-analyses of randomized controlled trials (RCTs) carried out in people with impaired glucose tolerance (IGT) (six studies) or dysmetabolism (one study) to answer the following questions: What is the evidence that T2D is preventable by lifestyle changes? What is the optimal diet (with a particular focus on diet quality) for prevention, and does the prevention of T2D result in a lower risk of late complications of T2D? The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach was applied to assess the certainty of the trial evidence. Altogether seven RCTs (N = 4090) fulfilled the eligibility criteria and were included in the meta-analysis. The diagnosis of incident diabetes was based on an oral glucose tolerance test (OGTT). The overall risk reduction of T2D by the lifestyle interventions was 0.53 (95% CI 0.41; 0.67). Most of the trials aimed to reduce weight, increase physical activity, and apply a diet relatively low in saturated fat and high in fiber. The PREDIMED trial that did not meet eligibility criteria for inclusion in the meta-analysis was used in the final assessment of diet quality. We conclude that T2D is preventable by changing lifestyle and the risk reduction is sustained for many years after the active intervention (high certainty of evidence). Healthy dietary changes based on the current recommendations and the Mediterranean dietary pattern can be recommended for the long-term prevention of diabetes. There is limited or insufficient data to show that prevention of T2D by lifestyle changes results in a lower risk of cardiovascular and microvascular complications.
Highlights
Both the prevalence and incidence of type 2 diabetes (T2D) are increasing rapidly worldwide.Worldwide, in 2017, approximately 425 million people had diabetes
We selected randomized controlled trials (RCTs) comparing the effect of lifestyle intervention versus control on incident T2D defined using study-specific criteria based on a 2 h oral glucose tolerance test (OGTT) in all populations in an outpatient setting with a minimum follow-up of 1 year
5120 reports excluded based on the title and abstract: 790 duplicate reports; 1131 Not related to lifestyle behaviours; 1034 Non-randomized controlled trial (RCT) studies;; 1392 with subjects with diabetes at baseline; 545 Mixed lifestyle behaviours with other interventions; 228 Did not assess diabetes incidence
Summary
Both the prevalence and incidence of type 2 diabetes (T2D) are increasing rapidly worldwide. In 2017, approximately 425 million people had diabetes. This figure may rise to 629 million by 2045. In Europe, the prevalence of T2D is increasing in parallel to the obesity epidemic. In 2017, the number of patients with diabetes in Europe was 66 million (prevalence 9.1%) and it is estimated to be 81 million by 2045. The expenses for the treatment of diabetes are increasing mostly due to its long-term complications and modern drug treatment options [3]. Bariatric surgery is becoming more popular for markedly obese patients with T2D due to its significant beneficial effects on metabolic control, long-term complications, and prognosis of T2D [4,5]
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