The relationship between ageing and glucose homeostasis is still an open debate. In fact, the mechanisms by which glucose metabolism is progressively impaired with increasing age are not completely understood. In the present report we have reviewed the possible mechanisms (impaired insulin secretion and action, role of the environmental factors) which may lead to the impairment in glucose handling associated with ageing. We also point out that not all aged subjects are glucose intolerant; in fact, it has been suggested that only those aged subjects who present more than one pathological finding do in fact develop impaired glucose handling.