Impact of Obstructive Sleep Apnoea on Type 2 Diabetes and Vice Versa

Exploring the Shared Genetic Architecture Between Obstructive Sleep Apnea and Body Mass Index

Purpose

The reciprocal comorbidity of obstructive sleep apnea (OSA) and body mass index (BMI) has been observed, yet the shared genetic architecture between them remains unclear. This study aimed to explore the genetic overlaps between them.

Methods

Summary statistics were acquired from the genome-wide association studies (GWASs) on OSA (Ncase = 41,704; Ncontrol = 335,573) and BMI (Noverall = 461,460). A comprehensive genome-wide cross-trait analysis was performed to quantify global and local genetic correlation, infer the bidirectional causal relationships, detect independent pleiotropic loci, and investigate potential comorbid genes.

Results

A positive significant global genetic correlation between OSA and BMI was observed (r g = 0.52, P = 2.85e-122), which was supported by three local signal. The Mendelian randomization analysis confirmed bidirectional causal associations. In the meta-analysis of cross-traits GWAS, a total of 151 single-nucleotide polymorphisms were found to be pleiotropic between OSA and BMI. Additionally, we discovered that the genetic association between OSA and BMI is concentrated in 12 brain regions. Finally, a total 134 expression-tissue pairs were observed to have a significant impact on both OSA and BMI within the specified brain regions.

Conclusion

Our comprehensive genome-wide cross-trait analysis indicates a shared genetic architecture between OSA and BMI, offering new perspectives on the possible mechanisms involved.

Childhood Obesity and Respiratory Diseases: Which Link?

Prevalence of childhood obesity is progressively increasing, reaching worldwide levels of 5.6% in girls and of 7.8% in boys. Several evidences showed that obesity is a major preventable risk factor and disease modifier of some respiratory conditions such as asthma and Obstructive Sleep Apnea Syndrome (OSAS). Co-occurrence of asthma and obesity may be due to common pathogenetic factors including exposure to air pollutants and tobacco smoking, Western diet, and low Vitamin D levels. Lung growth and dysanapsis phenomenon in asthmatic obese children play a role in impaired respiratory function which appears to be different than in adults. Genes involved in both asthma and obesity have been identified, though a gene-by-environment interaction has not been properly investigated yet. The identification of modifiable environmental factors influencing gene expression through epigenetic mechanisms may change the natural history of both diseases. Another important pediatric respiratory condition associated with obesity is Sleep-Disordered Breathing (SDB), especially Obstructive Sleep Apnea Syndrome (OSAS). OSAS and obesity are linked by a bidirectional causality, where the effects of one affect the other. The factors most involved in the association between OSAS and obesity are oxidative stress, systemic inflammation, and gut microbiota. In OSAS pathogenesis, obesity's role appears to be mainly due to mechanical factors leading to an increase of respiratory work at night-time. However, a causal link between obesity-related inflammatory state and OSAS pathogenesis still needs to be properly confirmed. To prevent obesity and its complications, family education and precocious lifestyle changes are critical. A healthy diet may lead to an improved quality of life in obese children suffering from respiratory diseases. The present review aimed to investigate the links between obesity, asthma and OSAS, focusing on the available evidence and looking for future research fields.

The Interlinked Rising Epidemic of Insufficient Sleep and Diabetes Mellitus

For healthy existence, humans need to spend one-third of their time sleeping. Any qualitative or quantitative disturbances in sleep would result in an increased prevalence of obesity, metabolic disorders, diabetes, cardiovascular diseases, and hypertension. The paper aims to highlight the growing global problem of insufficient sleep and its significant impact on the rising incidence of diabetes mellitus. An extensive literature search was done in all major databases for "insufficient sleep" and "Diabetes Mellitus" for this review. Shorter (<6 h) and longer (>9 h) durations of sleep have been adversely related to insulin resistance. Though the relation between insufficient sleep and diabetes mellitus is more or less understood, little is known about how oversleeping or hypersomnia (10⁻12 h) increases the risk of diabetes. The relationship between sleep disturbances and diabetes is dual-sided, as chronic sleep disturbances would elevate the risk of developing insulin resistance, while diabetes would worsen the quality of sleep. Both the qualitative and quantitative disturbances in sleep significantly increase the risk of developing diabetes, which is supported by numerous community-based and hospital-based epidemiological studies discussed in this review. Obstructive sleep apnea is one of the most common sleep disorders and is characterized by chronic intermittent hypoxia and increased sympathetic activity, thus leading to a higher prevalence of diabetes. Sleep therapy may serve as a low-cost method for fighting against the rising epidemic of diabetes.

Sleep disturbances in diabetic peripheral neuropathy patients: a clinical and polysomnographic study

Background

Disordered sleep breathing is a common complication of diabetic peripheral neuropathy (DPN) manifested by excessive daytime sleepiness, morning headache, morning dizziness, cognitive decline, and mood changes.

Methods

This study was performed on 30 non-obese type 2 diabetic patients; 20 with clinically evident DPN and 10 without. Ten age-, sex-, and body mass index-matched healthy control subjects were also included. Patients and control were subjected to history taking, neurological examination, glycated hemoglobin, and clinical assessment of the sensori-motor manifestations by the neuropathy symptom score and neuropathy disability score. The autonomic nervous system was evaluated clinically by the systolic blood pressure response to standing and heart rate response to each of standing, Valsalva, and deep breath. Finally, sleep was assessed by one-night polysomnogram (PSG) followed by multiple sleep latency test in the next day.

Results

The study showed significant increase in sleep apnea syndromes in diabetic peripheral neuropathy patients compared to diabetic neuropathy free patients and healthy control (p < 0.0001). The sleep apnea was mainly obstructive and to a little extent mixed (obstructive/central) sleep apnea. The severity of sleep PSG abnormalities was positively correlated with the severities of sensory, motor, and autonomic manifestations.

Conclusions

Non-obese type 2 diabetic patients complicated by peripheral neuropathy especially those having dysautonomia are at increased risk of developing sleep disordered breathing resulting in their excessive daytime sleepiness, decreased productivity, and poor glycemic control.

New Insight into the Role of Obstructive Sleep Apnea in Cardiometabolic Diseases

Humans spend almost one third of their life sleeping, thus sleep deprivation or poor sleep quality will have consequences upon the quality of life. Obstructive sleep apnea (OSA) is the most common sleep disorder that represents a respiratory cessation for at least ten seconds, which appears repeatable during sleep and it is accompanied by decreased oxygen saturation. The diagnosis of OSA is possible by filling in the STOP, STOP BANG, BERLIN questionnaires and performing the polysomnography, an accessible and more accurate method but yet very expensive. The prevalence of OSA is continuously increasing, but because of the nonspecific symptoms, the percentage of un-diagnosed cases is further increased. Data from 11 epidemiological studies published between 1993 and 2014 indicated an OSA prevalence of 22% in men and 17% in women. It has been suggested that there is a bidirectional causal relationship between OSA and obesity, and numerous studies have shown association of OSA with insulin resistance, diabetes mellitus, diabetic micro- and macrovascular complications and atrial fibrillation.