Obstructive Sleep Apnea Increases Visceral Fat Deposition but Not Total Body Fat Percentage

Abstract

Obstructive Sleep Apnea (OSA) is a prevalent sleep disorder in which obesity is a risk factor. Despite this relationship, OSA increases the risk for developing diabetes mellitus (DM) independent of total body adiposity. The mechanisms linking OSA and DM are complex and not well understood. Visceral fat is a well-established risk factor for DM due to its increased metabolic properties, and may be a contributing factor in the link between OSA and DM. PURPOSE: To examine the differences in total body and visceral fat in OSA vs. non-OSA controls. METHODS: Ten OSA and 21 control subjects were grouped by an at-home, sleep-screening device. All OSA subjects were classified as having moderate-severe OSA. Total body and visceral fat was assessed by DEXA. Physical activity was measured in each subject by hip-worn accelerometry. RESULTS: OSA subjects were significantly older (39.5 + 14.0 vs. 28.1 + 11.5 years; P = 0.02) and had a higher BMI (32.96 + 7.13 vs. 28.5 + 3.2; P = 0.02) than controls. There was no difference between groups in mean steps per day. Total percent body fat did not differ between groups before or after adjustment for age and BMI (35.31 + 7.4 vs. 34.51 + 8.7 for OSA and control subjects, respectively). Visceral fat percentage was significantly higher in OSA before adjusting for age and BMI (5.2 + 3.2 lbs vs. 1.8 + 1.6 lbs; P = 0.014). This difference remained significant after adjustment (P < 0.01). Further, the apnea-hypopnea index (AHI), the measure to quantify OSA severity, was highly correlated with visceral fat (r = 0.74; P < 0.01). CONCLUSION: Results suggest that, despite no difference in total body adiposity, visceral fat is increased in those with OSA. Visceral fat has been associated with decreased insulin sensitivity and glucose intolerance. This may be one of the many contributory mechanisms involved in the increased risk and prevalence of DM in OSA.