Diet and exercise in the prevention and treatment of type 2 diabetes mellitus

Evidence from observational studies and randomized trials suggests that prediabetes and type 2 diabetes mellitus (T2DM) can develop in genetically susceptible individuals in parallel with weight (that is, fat) gain. Accordingly, studies show that weight loss can produce remission of T2DM in a dose-dependent manner. A weight loss of ~15 kg, achieved by calorie restriction as part of an intensive management programme, can lead to remission of T2DM in ~80% of patients with obesity and T2DM. However, long-term weight loss maintenance is challenging. Obesity and T2DM are associated with diminished glucose uptake in the brain that impairs the satiating effect of dietary carbohydrate; therefore, carbohydrate restriction might help maintain weight loss and maximize metabolic benefits. Likewise, increases in physical activity and fitness are an important contributor to T2DM remission when combined with calorie restriction and weight loss. Preliminary studies suggest that a precision dietary management approach that uses pretreatment glycaemic status to stratify patients can help optimize dietary recommendations with respect to carbohydrate, fat and dietary fibre. This approach might lead to improved weight loss maintenance and glycaemic control. Future research should focus on better understanding the individual response to dietary treatment and translating these findings into clinical practice. This Review highlights the evidence from clinical trials that diet-induced weight loss interventions can be used to treat type 2 diabetes mellitus. The composition of the diet and the importance of physical exercise programmes are discussed. Lifestyle interventions for prevention of type 2 diabetes mellitus are also considered. Key points Studies show that weight loss can produce remission of type 2 diabetes mellitus (T2DM) in a dose-dependent manner. In patients with T2DM and obesity, weight loss of ~15 kg, achieved by an intensive management programme involving calorie restriction, can lead to remission of T2DM in ~80% of individuals. Long-term maintenance of weight loss and metabolic health in people who have undergone intensive lifestyle intervention is challenging. Carbohydrate restriction might help maintain weight loss and maximize metabolic benefits. When combined with calorie restriction and weight loss, increases in physical activity and fitness are an important contributor to T2DM remission. Preliminary work suggests that pretreatment glycaemic status could be us