Glucose and arterial blood pressure variability in obstructive sleep apnea syndrome

INTRODUCTION: Current evidence supports an association between Obstructive Sleep Apnea Syndrome (OSAS), insulin resistance, type 2 diabetes mellitus (DM) and cardiovascular disorders. The relationship is complex and still remains poorly understood. AIM: The aim of this study was to examine the potential correlation of sleep characteristics with glucose and arterial pressure values variability in non -diabetic, non-hypertensive patients with OSAS. SUBJECTS AND METHODS: We examined 22 subjects, 11 men and 11 women (mean age 54 +/- 14,5 years), recently diagnosed with OSAS (Apnea -Hypopnea Index (AHI) >= 5 apneas/hypopneas per hour of sleep) by full night polysomnography (PSG). Fasting and postprandial after a 2 hour oral glucose tolerance test (OGTT) glucose and insulin levels were measured, and homeostatic model assessment of insulin resistance (HOMA(IR)) index profile as well as Matsuda insulin sensitivity index (ISI) were calculated. A 24 hour glucose monitoring with subcutaneous measurements every 5 minutes and a 24-hour arterial blood pressure (ABP) monitoring (Holter monitoring) were evaluated. RESULTS: AHI, a widely accepted marker of the severity of OSAS, was correlated with HOMA and Matsuda index (p = 0.016 and p = 0.022, respectively), Standard Deviation (SD) of glucose measurements (p = 0.05) and mean diastolic blood pressure (p = 0.007). Percentage of sleep time with saturation of hemoglobin with oxygen, as measured by pulse oximetry, (SpO(2) ) < 90% was also correlated with HOMA and Matsuda index (p = 0.014 and p = 0.012, respectively), coefficient of variation (CV) of glucose measurements (p = 0.009) and SD of 24-hour systolic blood pressure. Moreover, minimum SpO(2) was correlated with glucose levels (p = 0.018), Matsuda index (p = 0.30) and SD of 24-hour diastolic and systolic blood pressure (p = 0.005 and p = 0.022, respectively). CONCLUSIONS: Glucose and arterial pressure variability were associated with markers of OSAS severity (AHI, % sleep time with SpO(2) < 90%, min SpO(2)), among nondiabetic patients. Thus, glucose and arterial pressure variability in OSAS may be an additional marker of cardiovascular risk as well as of future diabetes in these subjects. Nevertheless, the clinical significance of our observations remains to be confirmed by prospective studies.