Disorders of glucose metabolism and insulin resistance in patients with obstructive sleep apnoea syndrome

Abstract

Objective: Insulin resistance (IR) and disorders of glucose metabolism (DGM) are risk factors for cardiovascular diseases. There are different reasons for development of DGM in patients with obstructive sleep apnoea syndrome (OSAS) and this association is controversial. We investigated the frequency of DGM and IR in patients with OSAS and determining factors for these disorders.

Method: One hundred and twelve untreated patients with OSAS and 19 non-apnoeic snoring subjects upon polysomnography were included in this study. Oral glucose tolerance test (OGTT) was performed in all subjects who had fasting blood glucose < 125 mg/dl. IR method was analysed using homeostasis assessment model (HOMA-IR). Diabetes mellitus (DM), impaired glucose tolerance (IGT) and impaired fasting glucose (IFG) were defined according to values of OGTT. DGM was defined as having one of the diagnoses of DM, IGT or IFG. Subjective sleepiness of all subjects was assessed with Epworth Sleepiness Scale (ESS). Excessive daytime sleepiness (EDS) was described as ESS score ≥ 10.

Results: Fasting glucose and the rate of DGM in patients with OSAS were higher than in non-apnoeic snoring subjects. DGM were shown in % 15.7 of non-apnoeic snoring subjects, 29.6% of mild sleep apnoea, 50% of moderate sleep apnoea and 61.8% of severe sleep apnoea. The rate of DGM in patients with moderate and severe OSAS was higher than in non-apnoeic snoring subjects and in patients with severe OSAS higher than in patients with mild OSAS. DGM are associated with body mass index (BMI), severity of OSAS, arousal index and EDS. In addition, IR is associated with apnoea hypopnoea index, BMI, arousal index and ESS score.

Conclusion: Obstructive sleep apnoea syndrome is associated with high frequency of DGM. In addition, the progression of disease from simple snoring and mild OSAS to severe OSAS increases the rate of DGM. Thus, DGM especially in patients with severe OSAS should be examined in regular periods.