Plasma insulin and lipid levels in untreated obstructive sleep apnoea and snoring; their comparison with matched controls and response to treatment

Abstract

Obstructive sleep apnoea (OSA), and snoring are associated with coronary heart disease. To assess whether OSA or snoring may contribute to this by raising fasting lipid or insulin levels, venous fasting total cholesterol, triglyceride, very-low-density lipoprotein, low-density lipoprotein, high-density lipoprotein, and insulin were measured in 15 untreated OSA patients and 18 snorers. Each of these subjects was individually 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 patients were then treated with nasal continuous positive airway pressure. In 10 of these subjects lipid and insulin levels were repeated after more than three months treatment. Lipid and insulin levels were also remeasured in the controls matched to these 10 subjects. The end points were compared with paired t-tests. There was no difference in any of the end points when the untreated OSA patients and the snorers were compared to their matched controls (P > 0.25 for all comparisons), and none of the indices changed when OSA was corrected with nasal continuous positive airway pressure (P > 0.25 for all comparisons). Patients with obstructive sleep apnoea or snoring do not have significant fasting hyperlipidaemia or hyperinsulinaemia when compared to carefully matched controls. These factors are therefore unlikely to be the cause of the excess cardiovascular mortality experienced by this patient group.

Sleep, sleep-disordered breathing and metabolic consequences

“…Similar data have been obtained in samples of OSA patients (tables 3 and 4) [64][65][66][67][68][69][70][71][72][73][74][75][76][77][78][79][80], with a large prevalence of positive [63,[64][65][66][67][68][69][70][71][72][73][74][75][76][77][78][79] rather than negative [78][79][80] studies. In clinical populations, OSA patients characterised by full-PSG were significantly more likely to have impaired glucose tolerance (IGT) and diabetes than subjects free of OSA syndrome (OSAS) [71].…”

Sleep Apnea and Daytime Sleepiness and Fatigue: Relation to Visceral Obesity, Insulin Resistance, and Hypercytokinemia

“…In contrast, two other controlled studies suggested that the relation between sleep apnea and plasma insulin levels (4) or insulin resistance (5) reflected the known effects of obesity. However, in one of these studies the apneics were otherwise healthy normotensive individuals (5), whereas in the second one they were lean and less symptomatic than our patients (4).…”

“…Studies of the potential independent role of sleep apnea in the development of insulin resistance and/or vice versa have been inconsistent and inconclusive. Recent studies suggested that the effects of sleep apnea on insulin dynamics and effects could be accounted for completely by obesity (4,5).…”

Sleep Apnea and its Association with the Stress System, Inflammation, Insulin Resistance and Visceral Obesity

“…In contrast, two other controlled studies suggested that the relation between sleep apnea and plasma insulin levels (63) or insulin resistance (64) reflected the known effects of obesity. However, in one of these studies, the apneics were otherwise healthy normotensive individuals (64), whereas in the second one, the apneics were lean and less symptomatic (63). The weak correlations between sleep apnea and insulin levels in clinical samples and the absence of insulin resistance in otherwise asymptomatic apneics reported in some studies may be due to the possibility that sleep apnea is a heterogeneous disorder in terms of its association with insulin resistance and/or that sleep apnea without symptoms has a weak association with insulin resistance.…”