Smoking is a predictor of the transition from normoglycaemia to impaired fasting glucose and increases the risk of type 2 diabetes, independent from possible confounders. In patients with diabetes as in non-diabetics, smoking is a significant and independent risk factor for all-cause mortality and for mortality from cardiovascular disease and corononary heart disease, as well as for aggregates of fatal and non-fatal cardiovascular events. There is little doubt that smoking is a risk factor for coronary heart disease, but this risk appears to be stronger than the risk for stroke in diabetics. Pathophysiological mechanisms by which smoking causes glucose intolerance and worsens clinical outcomes in established diabetes include greater insulin resistance, impaired beta-cell function and insulin secretion, chronic low-grade inflammation, endothelial dysfunction, as well as interacting indirectly with other factors known to aggravate diabetes and lifestyle factors. Smoking cessation programs are of great importance for primary care specialists dealing with diabetes.