Insuline resistance and insuline sensibility in patients with obstructive sleep apnea

Abstract

Obstructive sleep apnea (OSA), also referred to as obstructive sleep apnea-hypopnea (OSAH), is a sleep disorder that involves cessation or significant decrease in airflow in the presence of breathing effort. It is the most common type of sleep disordered breathing (SDB) and is characterized by recurrent episodes of upper airway collapse during sleep. These episodes are associated with recurrent oxyhemoglobin desaturations and arousals from sleep. Despite being a common disease, OSAS is underrecognized by most primary care physicians; an estimated 80% of Americans with OSAS are not diagnosed. Apnea may occur hundreds of times nightly, 1-2 times per minute, in patients with severe OSA, and it is often accompanied by wide swings in heart rate, a precipitous decrease in oxygen saturation, and brief electroencephalographic (EEG) arousals concomitant with loud breathing sounds as a bolus of air is exhaled when the airway reopens. The cardinal symptoms of sleep apnea include the "3 S s": S noring, S leepiness, and S ignificant-other report of sleep apnea episodes. Recent studies suggest that OSA increases the risk of developing insulin resistance and type 2 diabetes. The aim of the present study was to assess whether obstructive sleep apnea is a risk factor for insulin resistance, using surrogate estimates of insulin-mediated glucose uptake. We studied a population of 174 (122 males) subjects evaluated in our Sleep Lab for the suspect of OSA. All subjects underwent a standard nocturnal polysomnography (Compumedics S-Series). The HOMA index, an index of insulin resistance and the QUICKI index, an index of insulin sensitivity, were calculated from the values of fasting glucose and insulin obtained in the morning. The percentage of patients with iper-trigliceridemia was significantly higher in patients with OSAS than in controls (P <00.5) . Insulin resistance (HOMA > 2.4) was higher in OSAS patients than in controls (P < 00.5), as well as BMI values were higher in patients with OSAS than in controls (P < 00.5) . The results showed that the risk factors for insulin resistance (HOMA > 2:45 ) were predominantly the BMI (OR 2.4, 95 % CI 1.3-4.6 , P <0.001) , OSA (OR 4.0, 95 % CI 1.6 -9.7 , P <0.001) and hypertension (OR 2.3 , 95% CI 1.2-4.3 , P<0.001). Revealed no correlation with sex , age, hypercholesterolemia and ipertrigligeridemia . We did a multiple regression in which the OSAS (OR 2.7, 95 % CI 1.2-3.70 , P <0.05) and BMI (OR 2.3, 95% CI 0.29-2.70 , P <0.05), but not hypertension (OR 1.8, 95% CI 0.8-6.0, P <0.8) were independent risk factors for insulin resistance. From the correlation between insulin levels and OSAS we got a positive relationship between insulin and AHI (r = 0:32, P <0.001) and insulin levels and BMI (r = 0:43, P <0.001).