Smoking, obesity and diabetes are among the leading cause of premature death worldwide. Smokers have globally a lower body weight compared with non smokers but they tend to accumulate more fat in the abdomen. Most smokers gain weight when they quit smoking, however this does not seem to diminish the health benefits associated with smoking cessation. Smoking increases the risk of developing type 2 diabetes. Among people with diabetes, smoking significantly increases the risks of complications and mortality. Interventions with pharmacologic help should be offered to all smokers, with or without diabetes, in order to increase smoking cessation rates and limit weight gain.