BACKGROUND: Mild obstructive sleep apnea (OSA) is a highly prevalent disorder in adults. However, it is not clear whether mild OSA has significant metabolic complications. This study examined the prevalence of metabolic syndrome (MS) in patients with mild OSA compared to control group. METHODS: Adults (18-65 years of age) of both genders with a body mass index (BMI) ≤35 kg/m were included. The mild OSA group comprised of patients with an apnea-hypopnea index (AHI) score of ≥5 but ≤15 events/hr of sleep, independent of other symptoms. The control group (CG) comprised individuals with an AHI of <5 events/hr of sleep and an Epworth Sleepiness Scale score of <10. The following were used for both groups: two questionnaires on sleepiness, the maintenance of wakefulness test, and full-night polysomnography. Anthropometric measurements and fasting blood samples were obtained, including fasting glucose and insulin, total cholesterol and its subfractions [low-density lipoprotein, very low-density lipoprotein, and low-density lipoprotein cholesterol (HDL-c)], triglycerides (TG), and the TG/HDL-c ratio. In addition, the quantitative insulin sensitivity check index and homeostasis model assessment indices were calculated. RESULTS: Thirty-two percent of mild OSA patients had MS, 43.5% of mild OSA patients had hypertension, 14% showed dyslipidemia, and 56% had prediabetes. The OSA group showed increased TG (CG: 90.0 ± 51.9 vs. OSA: 140.3 ± 78.2 mg/dL, P = 0.004), and TG/HDL-c (CG: 1.9 ± 1.4 vs. OSA: 3.1 ± 2.0, P = 0.05), independent of adjustments. Independent of obesity (BMI <30 kg/m), there was a negative correlation between total cholesterol and TG with mean oxygen saturation, independent of obesity (BMI <30 kg/m). CONCLUSIONS: Our findings showed dysregulation in lipid profiles after adjustments for confounders in the mild OSA group, and there was a correlation between these parameters and sleep hypoxemia. The TG/HDL-c ratio in particular was high, suggesting that it might be investigated as a marker of a detrimental metabolic profile in these patients.