Interventions to improve glycaemic control in people living with, and at risk of developing type 2 diabetes

Type 2 diabetes mellitus is one of the most prevalent health conditions worldwide, affecting millions of individuals and posing significant public health challenges. Understanding the nature of type 2 diabetes, its causes, symptoms and treatments is crucial for managing and preventing its complications. Many different dietary strategies are used by individuals to treat and manage diabetes. This review provides an overview of popular dietary strategies that have evidence for improving long-term glycaemic control or achieving diabetes remission, as well as strategies that may be useful to reduce postprandial hyperglycaemia, which may be of use in the prevention of diabetes, but also as strategies for those already diagnosed but trying to manage their condition better. Recent clinical trials have provided evidence that in people living with type 2 diabetes who also live with overweight or obesity, using a total diet replacement weight loss programme results in significant and substantial weight loss, and as a result, many people can achieve remission from their diabetes. There has been considerable interest in whether similar effects can be achieved without reliance on formula foods, using real diet approaches. Reduced or low-carbohydrate diet approaches hold some promise, with observational or preliminary findings suggesting beneficial effects, but evidence from robust trials or systematic reviews of randomized controlled trials is still lacking. The Mediterranean dietary pattern, low in saturated fat and high in monounsaturated fat, also has some potential, with evidence to suggest some people can lose weight and achieve remission using this approach, which may be easier to adhere to longer term than more intensive total diet replacement and low-carbohydrate strategies. Plant-based diets that advocate for the elimination of animal-based and/or animal-derived foods have increased in popularity. There is evidence from epidemiological studies that people who follow these diets have a lower risk of developing type 2 diabetes, and evidence from trials and systematic reviews of trials that changing to a dietary pattern lower in animal-based and animal-derived foods has benefits on glycaemic control and other markers of cardiovascular disease. While these approaches all provide food or nutrient prescriptions, approaches that incorporate periods of fasting do not provide rules on the types of foods that can or cannot be consumed, but rather provide time windows of when to eat. Evidence suggests that these approaches can be as effective in achieving energy restriction and weight loss as approaches that advocate continuous energy restriction, and there is evidence for benefits on glycaemic control independent of weight loss. Finally, popular dietary strategies that may be useful to use or combine to help prevent postprandial hyperglycaemia include reducing the glycaemic index or glycaemic load of the diet, high-fibre diets, eating foods in a meal in the order vegetables > protein > carbohydrates, preloading or combining acids such as vinegar or lemon juice with meals and engaging in low-intensity aerobic exercise immediately after meals.