Patient selection

during rest. This may be accompanied by unpleasant sensations that are temporarily relieved by movement. Typically, the sen-sory-motor complaints of RLS arise or worsen during the night, showing a circadian pattern. RLS discomfort leads to a severe difficulty in initiating and maintaining sleep due to the fact that the motor activity carried out by patients in search of relief prolongs sleep latency and the frequent association of periodic limb movements during sleep causes arousals. Consequently, patients complain of insufficient and unsatisfactory sleep and of altered daytime functioning. Several conditions (such as iron deficiency,1 uremia,2 pregnan-cy,3 polyneuropathy,4 and rheumatoid arthritis5), which account for about one quarter of the clinical cases, have been associated with RLS, configuring a secondary or symptomatic form. With reference to type 2 diabetes mellitus, there are still no rigorous studies investigating the association between the endocrine dis-ease and RLS.6,7 An association between the 2 disturbances can be suspected, since both clinical conditions show at least 1 pos-sible common pathophysiologic mechanism (polyneuropathy) and diabetic patients are more at risk of presenting RLS than is the general population.8 The aims of this investigation were: (1) to look for an association between RLS and type 2 diabetes in a case-control study, (2) to analyze the characteristics of RLS in diabetic patients, and (3) to identify possible risk factors for the development of RLS in diabetic patients. METHOD