Associations between Sleep-Disordered Breathing and Metabolic Risk Factors beyond Obesity

Sex differences among sleep disordered breathing, obesity, and metabolic comorbidities; the Nagahama study

BACKGROUND

Although sex differences in the prevalence of sleep disordered breathing (SDB) is recognized, whether a sex difference exists among obese individuals with SDB with or without comorbidities has not been well investigated. This study aimed to explore the relationships of sex differences among SDB, obesity, and metabolic comorbidities.

METHODS

This study evaluated 7713 community participants with nocturnal oximetry ≥2 nights. SDB was assessed by the 3% oxygen desaturation index corrected for sleep duration obtained by wrist actigraphy (Acti-ODI3%), and moderate-to-severe SDB was defined as Acti-ODI3% levels ≥15/h. Obesity was defined as body mass index ≥25 kg/m2.

RESULTS

The prevalence of moderate-to-severe SDB was 21.6%/0% among those with obesity/without obesity in women under 40 years old. The adjusted odds ratios for moderate-to-severe SDB in those with both diabetes/metabolic syndrome and obesity compared to others were 86.4 (95%CI 24.2-308.8)/40.4 (95%CI 15.0-108.8) in pre-menopausal women. The association among SDB, obesity, and metabolic comorbidities showed significant interactions between pre-menopausal women and men or post-menopausal women.

CONCLUSIONS

Sex differences exist among the prevalence of SDB and the relationships among SDB, obesity, and metabolic comorbidities. Especially, pre-menopausal women are more vulnerable to the consequences of obesity. SDB prevalence may be impacted by the coexistence of obesity and diabetes or metabolic syndrome in pre-menopausal women.

Home-Based Aerobic Interval Training Combined with Resistance Training Improved Daytime Dysfunction in Adults with Obesity and Sleep-Disordered Breathing

Introduction  There have been many barriers to exercising at a gym due to the coronavirus disease 2019 (COVID-19) pandemic worldwide. Home-based aerobic interval training (AIT) combined with resistance training (RT) may be helpful for obese adults with sleep-disordered breathing (SDB) to overcome those barriers and improve their subjective sleep disorders. Thus, the present study aimed to examine the effects of home-based AIT combined with RT on subjective sleep disorders in obese adults with SDB. Material and Methods  This study has a one-group pretest-posttest design. Twenty-one adults with obesity and SDB were assigned to perform 8 weeks of AIT combined with RT. Subjective sleep disorder variables including the Pittsburgh Sleep Quality Index (PSQI), Berlin Questionnaire, and Epworth Sleepiness Scale were defined as primary outcomes. Anthropometric variables, physical fitness components, and blood biomarkers were assigned as secondary outcomes. All outcome measurements were examined at baseline and after 8 weeks of training. Results  Daytime dysfunction of PSQI was significantly improved after 8 weeks of the exercise program ( p  < 0.05). Upper and lower chest expansion and estimated maximum oxygen consumption were significantly increased after 8 weeks of the exercise program (all p  < 0.05). None of the blood biomarkers changed after 8 weeks of training. Conclusion  This study suggests that home-based AIT combined with RT effectively alleviates daytime dysfunction and seems to be more helpful in improving global PSQI in adults with obesity. Future studies with a larger sample size, under a controlled trial are recommended to prove the benefits of the exercise program.

Obesity and Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is characterized by upper airway collapse during sleep. Chronic intermittent hypoxia, sleep fragmentation, and inflammatory activation are the main pathophysiological mechanisms of OSA. OSA is highly prevalent in obese patients and may contribute to cardiometabolic risk by exerting detrimental effects on adipose tissue metabolism and potentiating the adipose tissue dysfunction typically found in obesity. This chapter will provide an update on: (a) the epidemiological studies linking obesity and OSA; (b) the studies exploring the effects of intermittent hypoxia and sleep fragmentation on the adipose tissue; (c) the effects of OSA treatment with continuous positive airway pressure (CPAP) on metabolic derangements; and (d) current research on new anti-diabetic drugs that could be useful in the treatment of obese OSA patients.

Circadian Melatonin Secretion In Obese Adolescents With Or Without Obstructive Sleep Apnea

Objective — To compare melatonin levels in saliva during a 24-hr day in order to identify the specificities of circadian melatonin secretion in obese adolescents with or without obstructive sleep apnea (OSA). Material and Methods — We examined 18 obese adolescents with OSA, 12 obese adolescents without OSA, and 15 healthy adolescents with a normal body weight, from whom saliva was sampled four time during the 24-hr day. Polysomnography was used to diagnose OSA. Saliva samples (n=180) were subjected to enzyme-linked immunosorbent assay. Results — Obese adolescents with OSA had higher evening melatonin levels than obese adolescents without OSA. For example, this indicator in OSA patients was 5.3 times higher than in participants without OSA, who had the lowest evening melatonin level among all groups. In both obese groups, nighttime melatonin levels were significantly lower than in the control group. A positive correlation was detected between the levels of morning and afternoon melatonin and body mass index only in obese adolescents without OSA (r=0.58; p=0.03 and r=0.68; p=0.01, respectively). It was found that evening melatonin correlated with minimum blood oxygen saturation (SaO2) in the entire sample of adolescents with OSA (r=-0.69; p=0.008), and it also correlated with time with SaO2 <90% in the group with clinical manifestations of OSA (r=0.76; p=0.003). Nighttime melatonin levels negatively correlated with the minimum SaO2 value solely in the group with clinical manifestations of OSA (r=-0.58; p=0.035). Conclusion — The circadian melatonin secretion in obese adolescents differed, depending on the presence or absence of OSA, and correlated with the level of oxygen desaturation in OSA patients, to a greater extent – in the presence of clinical manifestations.

Sleep disordered breathing and metabolic comorbidities across sex and menopausal status in East Asians: the Nagahama Study

It is well known that the prevalence of sleep disordered breathing (SDB) is increased in patients with obesity or metabolic comorbidities. However, the way in which the prevalence of SDB increases in relation to comorbidities according to the severity of obesity remains unclear.

This cross-sectional study evaluated 7713 community participants using nocturnal oximetry ≥2 nights. SDB was assessed by the 3% oxygen desaturation index corrected for sleep duration obtained by wrist actigraphy (acti-ODI3%). SDB severity was defined by acti-ODI3%. Obesity was defined as body mass index ≥25 kg·m−2.

The prevalence of SDB was 41.0% (95% CI 39.9–42.1%), 46.9% (45.8–48.0%), 10.1% (9.5–10.8%) and 2.0% (1.7–2.3%) in normal, mild, moderate and severe SDB, respectively, with notable sex differences evident (males>post-menopausal females>premenopausal females). Comorbidities such as hypertension, diabetes and metabolic syndrome were independently associated with the prevalence of moderate-to-severe SDB, and coincidence of any one of these with obesity was associated with a higher probability of moderate-to-severe SDB (hypertension OR 8.2, 95% CI 6.6–10.2; diabetes OR 7.8, 95% CI 5.6–10.9; metabolic syndrome OR 6.7, 95% CI 5.2–8.6). Dyslipidaemia in addition to obesity was not additively associated with the prevalence of moderate-to-severe SDB. The number of antihypertensive drugs was associated with SDB (p for trend <0.001). Proportion of a high cumulative percentage of sleep time with oxygen saturation measured by pulse oximetry <90% increased, even among moderate-to-severe SDB with increases in obesity.

Metabolic comorbidities contribute to SDB regardless of the degree of obesity. We should recognise the extremely high prevalence of moderate-to-severe SDB in patients with obesity and metabolic comorbidities.

Association between dyslipidemia and plasma levels of branched-chain amino acids in the Japanese population without diabetes mellitus

BACKGROUND

Branched-chain amino acids (BCAAs) play a key role in energy homeostasis.

OBJECTIVE

We aimed to investigate the association between plasma BCAA levels and dyslipidemia in the Japanese population without diabetes mellitus.

METHODS

This cross-sectional study included 4952 participants without diabetes mellitus, enrolled in the Tsuruoka Metabolomic Cohort Study. Plasma BCAA levels were measured by capillary electrophoresis-mass spectrometry. Correlations between lipid and BCAA profiles were evaluated by sex-stratified multiple linear regression analyses, after adjusting for confounders. Logistic regression was used to identify associations between BCAAs and metabolic dyslipidemia (MD) defined as triglyceride levels ≥150 mg/dL, high-density lipoprotein cholesterol levels ≤40 mg/dL for men and ≤50 mg/dL for women, or low-density lipoprotein cholesterol (LDL-C) levels ≥140 mg/dL.

RESULTS

In both sexes, the levels of individual BCAAs and the total BCAA levels correlated positively with triglyceride levels and negatively with high-density lipoprotein cholesterol levels. Valine, leucine, and total BCAA levels were weakly and positively correlated with LDL-C levels. Increased BCAA levels showed positive associations with MD. However, associations between BCAAs and elevated LDL-C levels were unclear. Furthermore, the associations between BCAA levels and MD regardless of fasting blood sugar (FBS) levels (high or low). Although valine, leucine, and total BCAA levels were weakly associated with elevated LDL-C levels in the high-FBS group, no such association was observed in the low-FBS group.

CONCLUSIONS

BCAAs might be associated with MD independently of the FBS level and might play an important role in lipid metabolism and dyslipidemia.