Study Objectives: There are reports suggesting that obstructive sleep apnea (OSA) may itself cause weight gain. However, recent reports showed increases in body mass index (BMI) following continuous positive airway pressure (CPAP) treatments. When considering weight changes, changes in humoral factors that have signifi cant effects on appetite such as acyl (AG) and desacyl ghrelin (DAG), leptin, insulin, and glucose and their interactions, examples of which are AG/DAG and AG/insulin, are important. The aim of this study was to test the hypothesis that some appetite-related factors had a specifi c profi le before and after CPAP treatment. Methods: Metabolic parameters were measured crosssectionally while fasting and 30, 60, 90, and 120 min following breakfast in no or mild OSA (apnea-hypopnea index < 15, n = 15) and moderate-to-severe OSA (apnea-hypopnea index ≥ 15, n = 39) participants in a single institute. There were no differences in age, sex, BMI, or visceral fat accumulation between the two groups. Twenty-one patients with moderate-to-severe OSA who received CPAP treatment also prospectively underwent the same testing following 3 months of CPAP treatment. Results: Although fasting and postprandial glucose, insulin, and leptin levels did not differ between no or mild OSA and moderateto-severe OSA participants, AG and DAG, including AG/DAG and AG/insulin, under fasting and postprandial conditions were signifi cantly increased in the moderate-to-severe OSA patients (p < 0.01). After 3 months of CPAP treatment in 21 of the moderate-to-severe OSA participants, AG/DAG did not change signifi cantly, but other ghrelin-related parameters including AG/ insulin signifi cantly decreased compared with values before treatment but remained higher than in no or mild OSA. 1,2 Obesity is considered a major risk factor for OSA, and reports suggest that OSA may itself cause weight gain.3-5 When considering weight changes, humoral factors such as ghrelin, leptin, insulin, and glucose, which have signifi cant effects on appetite, are important.
6-8Most data on the associations between OSA and some humoral factors have been acquired in the fasting state.9-12 However, it is important to investigate not only fasting data but postprandial data because these humoral secretions are signifi cantly affected by food intake. [13][14][15] Ghrelin exists in 3 forms: acyl ghrelin (AG), desacyl ghrelin (DAG), and the fragmented form. Recent data showed that interactions between AG and DAG as well as between AG and insulin are important in the energy balance and insulin resistance in patients with conditions such as obesity,
BRIEF SUMMARYCurrent Knowledge/Study Rationale: It is said that there is a reciprocal interaction between obesity and obstructive sleep apnea (OSA). A few studies have shown that the treatment of OSA with continuous positive airway pressure (CPAP) is associated with a signifi cant reduction in body mass index (BMI), while other studies have found a signifi cant increase in BMI following CPAP treatment. It is important to ...