[Smoking, insulin resistance and type 2 diabetes]

Smoking is a major risk factor for cardiovascular disease. It is associated with endothelial dysfunction and lipid disorders similar to those found in the insulin resistance syndrome. Studies have thus tried to demonstrate a relationship between smoking and insulin resistance, and between smoking and type 2 diabetes mellitus. Even if their results may sometimes differ, smoking does seem to be associated with an impaired insulin sensitivity that is proportional to tobacco consumption. Nicotine replacement therapies seem also to generate a certain, though lower, degree of insulin resistance. If there is no major weight gain after smoking cessation, the latter is accompanied by a progressive return to normal insulin sensitivity. Several large epidemiological studies recently demonstrated that smoking could increase the risk of type 2 diabetes mellitus, with a relative risk between 1.5 and 3.0. Finally, among type 2 diabetic patients, smoking has a harmful effect on metabolic control and long-term complications of the disease, at least partially by increasing the components of the insulin resistance syndrome. All these observations represent further argument to promote smoking cessation in the general population, and more particularly in individuals at risk to develop type 2 diabetes, as well as in the diabetic population.