Metabolic and cardiovascular risk factors in narcolepsy

Narcolepsy might be a particular interesting clinical model to investigate the interaction of sleep and metabolism, because this rare sleep disorder involves central deficiency of orexins, known to be essential in sleep regulation and regulation of food intake and body weight. Moreover, obesity is a well-known feature of narcolepsy and reports suggest an increased incidence of type-II-diabetes. 82 patients of the German Narcolepsy Society were included. Blood glucose, HbA1c, cholesterol, LDL, HDL, triglyceride, uric acid, lipoprotein A and homocysteine levels were assessed in the morning. Anthropometric data were collected. To date, narcolepsy was confirmed in 62 patients (41F: 42±16y, BMI 29.3±7kg/m2; 21M: 49±16y, BMI 30.4±5kg/m2). Abnormal HDL levels were found in 16 patients (25.8%; mean±SD 58±17mg/dl). Parameter for homocysteine (10.4±3.3µmol/l), triglyceride (148±141mg/dl) and glucose (94±16mg/dl) in 14 patients (22.6%), LPA in 12 patients (19.4%, 21.6±32mg/dl), uric acid in 11 patients (17.7%, 5.1±1.4mg/dl), LDL in 9 patients (14.5%, 122±35mg/dl), cholesterol (199±40mg/dl) and HbA1c (5.4±0.5mg/dl) in 5 patients (8.1%) were also found to be abnormal. 21 patients (33.9%, 9F,12M) met the criteria for the metabolic syndrome as defined by the IDF. Our results suggest a high prevalence of individual metabolic abnormalities and the metabolic syndrome in narcoleptic patients. To clarify the clinical relevance, a comparison with a large non-narcoleptic population is planned.