Sleep duration, sleep quality and new markers of insulin resistance in obese subjects

Background: Sleep is an essential component of psychophysical well-being. Both insufficient duration and inadequate quality of sleep may increase the risk of diabetes mellitus, cardiovascular events and mortality. The relationship between short sleep duration and glucose disorders appears to be bidirectional. However, the link between duration, quality of sleep and new markers of insulin resistance (IR) in obesity is still unclear. Aim: To evaluate sleep duration and quality in a group of overweight/obese subjects and their association with metabolic variables and IR markers. Materials and methods: Anthropometric parameters, glycemic profile, biomarkers of IR were evaluated in adult patients with BMI >27 kg/m2 without severe OSA (Obstructive Sleep Apnea Syndrome). Sleep duration and quality were assessed using the PSQI (Pittsburgh Sleep Quality Index) questionnaire. IR was estimated using HOMA-IR, TyG index (Triglycerides-Glucose Index) and Tg/HDL ratio (triglycerides/HDL-cholesterol). Results: The 84 subjects included in the analysis (BMI 36.14 kg/m2, waist circumference 110.42 cm) had a mean age of 54,65 years. The mean values of HOMA-IR (4.99±3.88), Tg/HDL (2.8±1.42) and TyG (4.74±0.25) were suggestive of a condition of insulin resistance. Nearly half of the patients (45%) had severe obesity and 84% had diabetes or IFG/IGT. The overall quality (total PSQI 7.63) and duration of sleep (5.76 hours) were not satisfactory and 59.5% of the patients had a total PSQI score >5, indicative of altered sleep quality. When patients were divided according to the sleep quality, subjects with PSQI >5 (poor sleep quality) had higher values of BMI, waist circumference, and waist-to-height ratio, as compared to those with PSQI ≤5. Markers of IR, glycemic and lipid profile were similar in the two groups. Mean PSQI score and the percentage of subjects with poor sleep quality were significantly higher in patients with class II/III obesity, compared to those with BMI<35 Kg/m2 (9.38 vs 6.02 respectively, p<0.001 and 77% vs 43% p 0.04). Conclusions: In this group of overweight/obese patients without severe OSA, we did not observe any association of sleep quality and duration with markers of IR. Sleep duration and quality were inadequate, especially in subjects with more severe degrees of obesity, suggesting an inverse relationship between sleep quality and visceral obesity.