PLASMA-INSULIN AND LIPID-LEVELS IN UNTREATED OBSTRUCTIVE SLEEP-APNEA AND SNORING - THEIR COMPARISON WITH MATCHED CONTROLS AND RESPONSE TO TREATMENT

Obstructive sleep apnoea (OSA), and snoring are associated with corona ry heart disease. To assess whether OSA or snoring may contribute to t his by raising fasting lipid or insulin levels, venous fasting total c holesterol, triglyceride, very-low-density lipoprotein, low-density li poprotein, high-density lipoprotein, and insulin were measured in 15 u ntreated OSA patients and 18 snorers. Each of these subjects was indiv idually matched to a control of the same sex, age +/- 10%, body index +/- 15%, smoking and drinking habits. This produced study groups which did not differ significantly by any of these criteria. Fasting venous blood samples were collected at 06.30 hours following polysomnography , and analysed blind of the subjects respiratory status. The OSA patie nts were then treated with nasal continuous positive airway pressure. In 10 of these subjects lipid and insulin levels were repeated after m ore than three months treatment. Lipid and insulin levels were also re measured in the controls matched to these 10 subjects. The end points were compared with paired t-tests. There was no difference in any of t he end points when the untreated OSA patients and the snorers were com pared to their matched controls (P > 0.25 for all comparisons), and no ne of the indices changed when OSA was corrected with nasal continuous positive airway pressure (P > 0.25 for all comparisons). Patients wit h obstructive sleep apnoea or snoring do not have significant fasting hyperlipidaemia or hyperinsulinaemia when compared to carefully matche d controls. These factors are therefore unlikely to be the cause of th e excess cardiovascular mortality experienced by this patient group.