Glucose Tolerance in Patients with Narcolepsy

Study Objectives: Obesity is a common feature of narcolepsy. In addition, an increased occurrence of non-insulin dependent diabetes has been reported. So far, it is not known whether glucose metabolism in narcolepsy is disturbed due to, or independently of obesity. Design: Case-control study. Setting: Sleep medicine clinic at a research institute. Patients: We studied 17 patients with narcolepsy/cataplexy compared to 17 healthy controls matched for age, sex, and body mass index (BMI). Interventions: A 75-g oral glucose tolerance test was performed. Measurements: Glucose tolerance was determined by computing plasma glucose curve following oral glucose challenge for 240 minutes; insulin sensitivity and insulin secretion by homeostasis model assessment and minimal model analysis. Results: Standard outcome measures and indices of the oral glucose tolerance test did not differ between the patient group and the group of control subjects. Conclusions: In this study, no clinically relevant pathologic findings in the glucose metabolism of narcoleptic patients compared to weight matched controls were found. Thus, narcolepsy is unlikely to be a risk factor per se for impaired glucose tolerance or diabetes.