Medical nutrition therapy for the management of type 2 diabetes mellitus.

Type 2 diabetes mellitus (T2DM) is a major global health concern. Medical nutrition therapy has a key role in T2DM management, with dietary interventions being central to improving glycaemic control and overall metabolic health. Growing evidence suggests that certain dietary strategies can exert direct metabolic benefits independent of weight reduction. The Mediterranean diet has consistently demonstrated metabolic and cardiovascular benefits, along with improved glycaemic control, even in the absence of substantial weight reduction. Low-energy and very-low-energy diets, characterized by moderate to severe caloric restriction, respectively, have also been associated with improvements in cardiometabolic markers and glycaemic regulation. Ketogenic diets promote nutritional ketosis and have shown benefits on glycaemic control, insulin sensitivity and other metabolic outcomes, often preceding substantial weight loss. Intermittent fasting strategies, such as alternate-day fasting or the 5:2 model, and time-restricted eating, have likewise been linked to enhanced glycaemic control and favourable metabolic and cardiovascular effects, although their long-term efficacy and safety require further investigation. This Review aims to provide an evidence-based synthesis of the main nutritional strategies used in the treatment of T2DM, with a focus on their underlying mechanisms, clinical efficacy and potential for sustainable long-term implementation.