Position statement of the SEMI, SED, redGDPS, SEC, SEEDO, SEEN, SEMERGEN y SEMFYC.

Obesity and excess weight are the main preventable causes of type 2 diabetes (DM2). When diagnosing type 2 diabetes, clinicians should establish the degree of obesity according to the body mass index (BMI) and, for patients with excess weight, measure the waist circumference. The proper treatment of DM2 requires a simultaneous approach to excess weight/obesity and the other cardiovascular risk factors, such as hypertension, dyslipidaemia and smoking. Nondrug interventions (e.g., diet and exercise) have proven benefits in preventing and treating patients with DM2 and excess weight/obesity and should follow an individual and multidisciplinary approach, with structured programs equipped with specific resources. Weight gain associated with antidiabetic treatment can hinder glycaemic control, compromise treatment adherence, worsen the vascular risk profile and limit the cardiovascular benefits of treatment. Therefore, it is significant to avoid weight gain, a measure that can be cost-effective. Antidiabetic drugs with benefits in body weight have also demonstrated their benefit in patients with BMIs <30. In general, the treatment of patients with DM2 and obesity will depend both on the degree of obesity and the associated comorbidity. Clinical trials on DM2 intervention should consider combined objectives that include not only glycaemic control but also other variables such as the risk of hypoglycaemia and the effect of treatment on body weight.