Sleepiness as a marker of glucose deregulation in obstructive sleep apnea.

BACKGROUND: Excessive daytime sleepiness (EDS) is a major but not universally present feature of obstructive sleep apnea syndrome (OSAS). The latter has been associated with glucose dysmetabolism and insulin resistance. The aim of this study was to examine the role of EDS by investigating potential differences between somnolent and non-somnolent OSAS patients in glucose metabolism, insulin resistance, and levels of cardiovascular risk factors. METHODS: Included were 25 newly diagnosed otherwise healthy OSAS patients, reporting EDS (ESS ≥ 11) and 25 age- and BMI-matched, non-somnolent (ESS ≤ 10) OSAS patients, who served as controls. Fasting glucose and insulin levels, as well as homeostatic model assessment of insulin resistance (HOMA(IR)) index, levels of hs-CRP, and lipidemic profile were measured. RESULTS: The two groups did not differ in anthropometric or sleep characteristics. A significant correlation of ESS with glucose (p = 0.004), insulin (p = 0.011), and HOMA(IR) (p = 0.031) was observed. Somnolent patients had higher levels of glucose (p = 0.045), insulin (p = 0.012), and HOMA(IR) (p = 0.027). No difference was detected in other markers between the two groups. CONCLUSIONS: Daytime sleepiness in OSAS patients is associated with hyperglycemia and hyperinsulinemia. These results suggest its potential use as a surrogate marker of insulin resistance in such patients.

Markers of glycemic control and insulin resistance in non-diabetic patients with Obstructive Sleep Apnea Hypopnea Syndrome: does adherence to CPAP treatment improve glycemic control?

BACKGROUND AND AIM: Obstructive Sleep Apnea Hypopnea Syndrome (OSAHS) is associated with glucose dysmetabolism and insulin resistance, therefore the amelioration of breathing disturbances during sleep can allegedly modify the levels of markers of glucose regulation and insulin resistance, such as glycated hemoglobin, fasting glucose, insulin and HOMA(IR). The aim of this study was to explore the association between these parameters and sleep characteristics in non-diabetic OSAHS patients, as well as the effect of 6 months CPAP therapy on these markers, according to adherence to CPAP treatment. METHODS: Euglycemic patients (n=56; mean age+/-SD: 46.07+/-10.67 years) with newly diagnosed OSAHS were included. Glycated hemoglobin, fasting glucose, insulin levels and HOMA(IR) were estimated at baseline and 6 months after CPAP application. According to CPAP adherence, patients were classified as follows: group 1 (mean CPAP use 4 h/night), group 2 (mean CPAP use < 4 h/night) and group 3 (refused CPAP treatment), and comparisons of levels of the examined parameters were performed. RESULTS: At baseline, average SpO(2) during sleep was negatively correlated with insulin levels and HOMA(IR) while minimum SpO(2) during sleep was also negatively correlated with insulin levels. After 6 months, only group 1 patients demonstrated a significant decrease in glycated hemoglobin (p=0.004) accompanied by a decrease in hs-CRP levels (p=0.002). No other statistically significant change was observed. CONCLUSIONS: Nighttime hypoxia can affect fasting insulin levels in non-diabetic OSAHS patients. Good adherence to long-term CPAP treatment can significantly reduce HbA(1C) levels, but has no effect on markers of insulin resistance.

Effect of continuous positive airway pressure treatment on serum cardiovascular risk factors in patients with obstructive sleep apnea-hypopnea syndrome.

BACKGROUND: Serum levels of circulating markers associated with cardiovascular morbidity are elevated in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS). These factors are studied in patients mainly before the application of therapy with continuous positive airway pressure (CPAP), and the effects of CPAP treatment on them have not been thoroughly studied. Therefore, the aim of the study was to examine the effect of compliance to CPAP therapy on these factors. METHODS: Patients with newly diagnosed OSAHS, nonsmokers, without comorbidities or medication use, at baseline and during the follow-up period, were included. Serum cardiovascular risk factors (ie, high-sensitivity C-reactive protein [hs-CRP], homocysteine, total cholesterol, triglycerides, high-density lipoprotein cholesterol [HDL-C], low-density lipoprotein cholesterol, apolipoprotein A-I [ApoA-I], and apolipoprotein B [ApoB]) were measured at baseline and 6 months after CPAP application. Patients were classified into the following three groups according to CPAP use: group 1 (n = 20), good compliance (>or= 4 h use per night); group 2 (n = 19), poor compliance (< 4 h use per night); and group 3 (n = 14), refusal of CPAP treatment. RESULTS: Fifty-three patients (47 male patients and 6 female patients; mean [+/- SD] age, 46.09 +/- 10.87 years) were included in the study. In all groups, body mass index remained stable. In group 1, significant decreases in the levels of hs-CRP (p = 0.03), homocysteine (p = 0.005), total cholesterol (p = 0.021), total cholesterol/HDL-C ratio (p = 0.018), and ApoB/ApoA-I ratio (p = 0.021) was observed. The patients in group 2 showed a decrease in homocysteine levels (p = 0.021) only, while no significant changes were observed in the patients in group 3. CONCLUSIONS: Good compliance to CPAP treatment lowers the serum levels of cardiovascular risk factors, indicating a beneficial effect on the overall cardiovascular risk.