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Nutrition has long been recognised as a key feature in the management of diabetes. Before the introduction of insulin therapy, a heavily restricted dietary intervention, with the minimum carbohydrates necessary for survival, was used to treat the disease. The approach extended survival, in some cases allowing patients to live long enough to be treated with insulin once it became available.

Nowadays, from carbohydrate counting in people with type 1 diabetes to dietary counselling and interventions in people with type 2 diabetes, nutrition remains—at least in principle—a key component of diabetes care, as well as being central to prevention of type 2 diabetes, and to the emerging concept of type 2 diabetes remission or reversal.

On April 18, the American Diabetes Association (ADA) released a new consensus report on nutrition therapy in adults with diabetes. The first such update in 5 years, it also includes, for the first time, people with prediabetes. The goals of nutrition therapy include the promotion of healthy foods and eating patterns in order to improve control of glycaemia and other risk factors, reach and maintain bodyweight goals, and delay or prevent complications.

The report emphasises the efficacy and cost-effectiveness of nutrition therapy in people with diabetes, the importance of nutrition at diagnosis and regular reassessment throughout life stages and with changing health status, and the need for personalisation of dietary approaches—including to achieve clinically relevant weight loss.

With respect to dietary patterns and macronutrient distribution, the report maintains a flexible approach, with the authors noting that “there is not an ideal percentage of calories from carbohydrate, protein, and fat for all people with or at risk for diabetes”. Dietary counselling should be personalised, taking into account individuals’ current “eating patterns, preferences, and metabolic goals”, as well as cultural backgrounds, socioeconomic settings, and comorbidities.

The report reviews the evidence for several eating patterns, including Mediterranean-style, vegetarian and vegan, and various low-fat and low-carbohydrate diets. Recognising the lack of comparative evidence in favour of specific dietary patterns, the authors emphasise general recommendations, such as appropriate portion sizes and weight-loss targets among people with overweight or obesity, and key common dietary factors such as favouring of non-starchy vegetables and of whole over processed foods, and avoidance of added sugars and refined grains.

The inclusion of people with prediabetes in the ADA consensus report is an important development, highlighting increasing evidence for the effectiveness of dietary and lifestyle interventions in people at risk of type 2 diabetes. The effectiveness of such targeted prevention is further emphasised in an analysis from the Da Qing Diabetes Prevention Outcome Study in this issue of The Lancet Diabetes & Endocrinology. The investigators report observational results after 30 years of follow-up from the start of the original 6-year trial, showing that lifestyle intervention (diet, exercise, or both) delayed the onset of diabetes among people with impaired glucose tolerance by almost 4 years, leading to significant reductions in cardiovascular and microvascular complications, and increased life expectancy. Notably, the ADA consensus report recommends that people with prediabetes and overweight or obesity should be referred to an intensive lifestyle intervention (such as the US Diabetes Prevention Program) or to receive individualised nutrition support, targeting weight loss of 7–10%.

Importantly, the consensus statement also draws attention to the role of weight loss based on nutrition and lifestyle interventions in the remission of type 2 diabetes. The recent publication of the 2-year follow-up results of the DiRECT trial showed sustained remission for more than a third of participants who received the weight-loss dietary intervention (based on total diet replacement and stepped food reintroduction), with remission status linked to the extent of sustained weight loss. These findings emphasise the central role of nutrition and bodyweight in the pathogenesis of type 2 diabetes, and in its potential reversal, at least in some patients.

The ADA consensus statement thus underlines the crucial role of nutrition and bodyweight in type 2 diabetes, encompassing management, prevention, and reversal. While the debates and controversies around nutrition science in general are also apparent in relation to diabetes, the improving evidence base for different modes of dietary-induced weight change should lead to a greater emphasis on nutrition across the life course in people with (and without) type 2 diabetes.