Intermittent hypoxia is involved in gut microbial dysbiosis in type 2 diabetes mellitus and obstructive sleep apnea-hypopnea syndrome.

BACKGROUND: Obstructive sleep apnea (OSA)-hypopnea syndrome (OSAHS) has been recognized as a comorbidity of type 2 diabetes mellitus (T2DM); more than half of T2DM patients suffer from OSAHS. Intermittent hypoxia (IH) plays an important role in metabolic diseases, such as obesity and OSAHS, through various mechanisms, including altering the gut microecological composition and function. Therefore, it is important to study the role of gut microbiota in T2DM patients with OSAHS, which has a high incidence and is prone to several complications. AIM: To assess whether IH is involved in altering the fecal microbiome in T2DM patients with OSAHS. METHODS: Seventy-eight participants were enrolled from Henan Province People's Hospital and divided into healthy control (HC, n = 26), T2DM (n = 25), and T2DM + OSA (n = 27) groups based on their conditions. The fecal bacterial DNA of the research participants was extracted and subjected to 16S ribosomal RNA sequencing. The clinical indices, such as insulin resistance index, homocysteine (HCY) concentration, and the concentrations of inflammatory factors in the peripheral blood, were assessed and recorded. RESULTS: Group T2DM + OSA had the highest apnea-hypopnea index (AHI) (2.3 vs 3.7 vs 13.7), oxygen desaturation index (0.65 vs 2.2 vs 9.1), HCY concentration (9.6 µmol/L vs 10.3 µmol/L vs 13.81 µmol/L) and C-reactive protein (CRP) concentrations (0.3 mg/L vs 1.43 mg/L vs 2.11 mg/L), and lowest mean oxygen saturation (97.05% vs 96.6% vs 94.7%) among the three groups. Twelve and fifteen key differences in amplicon sequence variants were identified when comparing group T2DM + OSA with groups T2DM and HC, respectively. We found progressively decreased levels of Faecalibacterium, Eubacterium, and Lachnospiraceae, and an increase in the level of Actinomyces, which strongly correlated with the HCY, CRP, fasting plasma glucose, and hemoglobin A1c concentrations, AHI, mean oxygen saturation, and insulin resistance index in group T2DM + OSA (P < 0.05). CONCLUSION: For T2DM patients with OSAHS, IH may be involved in selective alterations of the gut microbiota, which may affect the pathophysiological development of T2DM and DM-related complications.

Gut microbiota and metabolic syndrome.

Metabolic syndrome (MetS) describes a set of risk factors that can eventually lead to the occurrence of cardiovascular and cerebrovascular disease. A detailed understanding of the MetS mechanism will be helpful in developing effective prevention strategies and appropriate intervention tools. In this article, we discuss the relationship between the clinical symptoms of MetS and differences in the gut microbial community compared with healthy individuals, characterized by the proliferation of potentially harmful bacteria and the inhibition of beneficial ones. Interactions between gut microbiota and host metabolism have been shown to be mediated by a number of factors, including inflammation caused by gut barrier defects, short-chain fatty acids metabolism, and bile acid metabolism. However, although we can clearly establish a causal relationship between gut microbial profiles and MetS in animal experiments, the relationship between them is still controversial in humans. Therefore, we need more clinical studies to augment our understanding of how we can manipulate the gut microbiota and address the role of the gut microbiota in the prevention and treatment of MetS.

Serum Fetuin-A Levels and Thyroid Function inMiddle-aged and Elderly Chinese.

Serum fetuin-A levels are reportedly elevated in hyperthyroidism. However, there are few relevant epidemiologic studies. We conducted a cross-sectional study in Songnan community, China in 2009 to investigate the association between serum fetuin-A concentrations and thyroid function. A total of 2,984 participants aged 40 years and older were analyzed. Multivariable linear regression analysis revealed that serum fetuin-A concentra- tions were positively associated with log (free triiodothyronine) and were inversely associated with log (thyroid peroxidase antibody) after adjustment (both P < 0.05). Compared with the participants in the lowest tertile of free triiodo-thyronine and free thyroxine level, those in the highest tertile had higher fetuin-A concentrations. Additionally, high serum fetuin-A concentrations were related to high thyroid function (odds ratio 1.27, 95% confidence interval 1.01-1.61), after adjustment for conventional risk factors.

Serum calcium level is associated with brachial-ankle pulse wave velocity in middle-aged and elderly Chinese.

OBJECTIVE: To study the relation between serum calcium level and elevated BaPWV in Chinese subjects. METHODS: The relation between serum calcium level and elevated BaPWV was studied in 9 615 subjects. The mean value of left and right BaPWV was analyzed. BaPWV was defined as high when it was ⋝1752.5 cm/s (the upper quartile) either side. RESULTS: The BaPWV and its elevated percentage progressively increased across the quartiles of the serum calcium level (P<0.05). The prevalence of elevated BaPWV was significantly higher in subjects of the second, third and highest quartiles than in those of the lowest quartile (26.9%, 28.4%, and 33.2% vs 23.7%, P=0.0116, P=0.0004, and P<0.0001). Logistic regression analysis revealed that the risk of elevated BaPWV was 1.32- fold higher in subjects of the highest quartile than in those of the lowest quartile (OR=1.32, 95% CI: 1.08-1.60). CONCLUSION: The elevated serum calcium level is related to an elevated BaPWV and a higher risk of arterial stiffness, independent of conventional risk factors, in middle-aged and elderly Chinese subjects.

Elevated resting heart rate is associated with dyslipidemia in middle-aged and elderly Chinese.

OBJECTIVE: To study the relationship between resting heart rate and blood lipid level. METHODS: A total of 9 415 subjects aged ⋝ 40 years were included in the present study. Their resting heart rate was monitored and their serum levels of triglyceride (TG), total cholesterol (TC), low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) were measured to define dyslipidemia according to the 2007 Chinese Guidelines on Prevention and Treatment of Dyslipidemia in Adults. RESULTS: The subjects were divided into group A with their resting heart rate <70 beats/min, group B with their resting heart rate =70-79 beats/min, group C with their resting heart rate =80-89 beats/min, and group D with their resting heart rate ⋝ 90 beats/min. High TG, TC, and LDL-C were presented across the resting heart rate (Ptrend <0.01). Multiple logistic regression analysis revealed that the risk of high TG and TC was higher in subjects with their resting heart rate ⋝ 90 beats/min than in those with their resting heart rate <70 beats/min (OR=1.42; 95% CI: 1.16-1.74 and OR=1.33; 95% CI: 1.09-1.64, respectively). CONCLUSION: Elevated resting heart rate is associated with high TG and TC in middle-aged and elderly Chinese subjects.