Good glycaemic control of diabetes mellitus is still hampered by the fear of insulin injections. Particularly in patients with type 2 diabetes, inhaled insulin as a novel therapeutic option for glycaemic control could be an alternative to subcutaneous insulin. Phase III clinical studies have shown glycaemic equivalence between inhaled insulin and conventional subcutaneous insulin. However, no study comparing inhaled insulin with short-acting insulin analogues has yet been published. Thus, methodological problems preclude conclusive remarks concerning quality-of-life issues. Inhaled insulin should be reserved for selected patient groups only. Lengthier studies to evaluate the long-term (pulmonary) safety of inhaled insulin and a cost-effectiveness study are needed.