The prevalance of restless legs syndrome and its effects on sleep quality in patients with type 2 diabetes mellitus

PURPOSE:In the present study, the frequency of RLS was investigated in 100 consecutive diabetic patients from outpatients clinics of Kocatepe University Hospital and contribution of this syndrome to the sleep quality and sleep disorders was also examined.METHODS:Overall, 22 patients with RLS (mean age was 55,2 ± 6,8 years, 6 of them were male) and 28 patients without RLS (mean age was 51,6 ± 7,0 years, 20 of them were male) admitted to the study. Blood and urine specimens was taken to evaluate the metabolic status of all patients. Besides, antropometric parameters were measured. The chronic complications of diabetes were evaluated. Sleep quality was assessed by the same physician using the Pittsburgh Sleep Quality Index (PSQI) and nighttime polysomnographic recordings were done.RESULTS:The mean age of the study group (24 female, 26 male) was 53.2±7.0 years, mean duration of diabetes was 11.4±6.3 years, and mean body mass index (BMI) was 29.7±5.1 kg/m2. Diabetic patients with and without RLS were similar with regards to age, duration of diabetes, hypertension, hyperlipidemia, and BMI. RLS was determined in 25% of the patients with type II DM. Woman were significantly more prevalant in RLS group (p=0.002). Laboratory and metabolic parameters were compared in patients with and without RLS. Hemoglobin levels were in normal range but significantly lower in patients with RLS (p=0.017). No significant differences were observed for other parameters. In RLS group, the patients with diabetic retinopathy and neuropathy were significantly higher in number (p=0.019, p=0.002). Subjective sleep quality for one month was assessed with Pittsburgh Sleep Quality Index (PSQI) questionnaire. The global score was significantly higher in the patients with RLS than those without RLS and the sleep quality was poorer in RLS group (p<0.001). The adequacy of sleep was lower (85%) than normal in both groups (mean 75,4%) in polysomnographic record of patients. REM stage of sleep was lower (mean 15,6%) than normal (20-25%) in both groups. REM sleep time was not significantly different between groups. NREM stage 1, defined as the period time from the awakening to the falling asleep, was longer (mean 11,4%) than normal (2-5%) in both groups, but there was no significant difference between patients with and without RLS. The mean period of NREM stage 2 was in the upper limits of normal (57,4%) in both groups. NREM stage 3 and 4, named as deep sleep stages, were lower (mean 15,2%) than normal (20-25%) in both groups, but there was no significant difference between patients with and without RLS (p=0.796). In comparison of periodic limb movements, total periodic limb movements during sleep index (PLMS total index) and NREM periodic limb movements during sleep index (NREM PLMS index) were significantly higher in patients with RLS than those without RLS (p<0.001 and p<0.001, respectively). The number of patients with diabetic neuropathy according to EMG measurements was 15 (68,2%) in RLS group and 7 (25%) in the group without RLS. This difference was significant (p=0.002). Sensory measurements of sural nerve were significantly lower in patients with RLS (p=0.019, p=0.044).CONCLUSION:In conclusion, the results of this study suggest that diabetic patients, in whom a variety of sleep disorders has been frequently seen, have poorer quality of sleep, especially when RLS coexist with DM. Poor quality of sleep in diabetic patients seems to be related to female gender, presence of retinopathy and neuropathy and concomitant RLS.