Continuous positive airway pressure and type 2 diabetes mellitus

Positive airway pressure (PAP) treatment reduces glycated hemoglobin (HbA1c) levels in obstructive sleep apnea patients with concomitant weight loss: Longitudinal data from the ESADA

Patients with obstructive sleep apnea (OSA) are at increased risk of developing metabolic disease such as diabetes. The effects of positive airway pressure on glycemic control are contradictory. We therefore evaluated the change in glycated hemoglobin (HbA1c) in a large cohort of OSA patients after long-term treatment with positive airway pressure. HbA1c levels were assessed in a subsample of the European Sleep Apnea Database [n=1608] at baseline and at long-term follow up with positive airway pressure therapy (mean 378.9±423.0 days). In a regression analysis, treatment response was controlled for important confounders. Overall, HbA1c decreased from 5.98±1.01% to 5.93±0.98% (p=0.001). Patient subgroups with a more pronounced HbA1c response included patients with diabetes (-0.15±1.02, p=0.019), those with severe OSA baseline (-0.10±0.68, p=0.005), those with morbid obesity (-0.20±0.81, p<0.001). The strongest HbA1c reduction was observed in patients with a concomitant weight reduction >5 kilos (-0.38±0.99, p<0.001). In robust regression analysis, severe OSA (p=0.038) and morbid obesity (p=0.005) at baseline, and weight reduction >5 kilos (p<0.001) during follow up were independently associated with a reduction of HbA1c following PAP treatment. In contrast, PAP treatment alone without weight reduction was not associated with significant Hb1Ac reduction. In conclusion, positive airway pressure therapy is associated with HbA1c reduction in patients with severe OSA, in morbidly obese patients. and most obviously in those with significant weight lost during the follow-up. Our study underlines the importance to combine positive airway pressure use with adjustments in lifestyle to substantially modify metabolic complications in OSA.

HMGB1/TLR4 promotes apoptosis and reduces autophagy of hippocampal neurons in diabetes combined with OSA

AIMS

Obstructive sleep apnea (OSA) combined with type 2 diabetes (T2DM) may lead to cognitive dysfunction. We previously reported that cognitive impairment is exacerbated in KKAy mice exposed to intermittent hypoxia (IH), during which the DNA binding protein HMGB1 mediates hippocampal neuronal apoptosis by maintaining microglia-associated neuroinflammation, but the underlying mechanism remains largely unknown.

MATERIALS AND METHODS

We performed immunofluorescence, Western blotting, and immunohistochemistry experiments in mouse hippocampal tissues and HT22 cells. KKAy type 2 diabetes model mice and normal C57BL/6J mice were exposed to IH or intermittent normoxia. HT22 cells were cultured in high glucose medium and exposed to IH or intermittent normoxia. We transfected HMGB1 siRNA into HT22 cells and then treated them with high glucose combined with intermittent hypoxia.

KEY FINDINGS

In conclusion, IH aggravated apoptosis and autophagy defects in T2DM mice, and increased the protein expression of HMGB1 and TLR4. This was also confirmed in HG + IH-treated hippocampal HT22 cells. HMGB1 siRNA can significantly reduce the protein expression of HMGB1 and TLR4, reverse neuronal apoptosis and enhance autophagy.

SIGNIFICANCE

We believe that HMGB1 is a key factor in the regulation of hippocampal neuronal apoptosis and autophagy defects in T2DM combined with OSA. Targeting HMGB1/TLR4 signaling as a novel approach may delay or prevent the increased apoptosis and decreased autophagy induced by T2DM combined with OSA, and may ultimately improve cognitive dysfunction.

Metabolic Consequences of Obstructive Sleep Apnea Especially Pertaining to Diabetes Mellitus and Insulin Sensitivity

Obstructive sleep apnea (OSA) and diabetes has been known to be closely related to each other and both diseases impact highly on the public health. There are many evidence of reports that OSA is associated with diabetes with a bidirectional correlation. A possible causal mechanism of OSA to diabetes is intermittent hypoxemia and diabetes to OSA is microvascular complication. However, OSA and diabetes have a high prevalence rate in public and shares the common overlap characteristic and risk factors such as age, obesity, and metabolic syndrome that make it difficult to establish the exact pathophysiologic mechanism between them. In addition, studies demonstrating that treatment of OSA may help prevent diabetes or improve glycemic control have not shown convincing result but have become a great field of interest research. This review outlines the bidirectional correlation between OSA and diabetes and explore the pathophysiologic mechanisms by approaching their basic etiologies.

Effects of continuous positive airway pressure therapy on glycaemic control, insulin sensitivity and body mass index in patients with obstructive sleep apnoea and type 2 diabetes: a systematic review and meta-analysis

Background:

Evidence suggests that 15–30% of individuals with obstructive sleep apnoea (OSA) have type 2 diabetes mellitus (T2DM), and that OSA is an independent risk factor for T2DM. There is considerable interest in ascertaining whether OSA treatment improves glycaemic control and insulin sensitivity in patients with OSA and T2DM.

Aims:

To assess the effects of continuous positive airway pressure (CPAP) therapy on glycosylated haemoglobin (HbA1c) level, insulin sensitivity and body mass index (BMI) in patients with OSA and T2DM.

Methods:

MEDLINE, EMBASE and the Cochrane Library were searched to identify prospective studies involving patients with OSA and T2DM who had received CPAP, and data on primary outcome (change in HbA1c) and/or secondary outcomes (changes in insulin sensitivity and BMI) were reported. All relevant studies published before 31 January 2014 were included.

Results:

Six studies were included in the systematic review and meta-analysis. The numbers of patients ranged from 9 to 44 (total=128), and mean age ranged from 50.7 to 66.1 years. For the change in HbA1c (six studies, 128 patients), the combined standardised paired difference revealed no significant effect of CPAP (−0.071, 95% confidence interval (CI)=−0.245, 0.103; P=0.421). Similarly, there was no significant effect of CPAP on the change in BMI (−0.102, 95% CI=−0.296, 0.092; P=0.302; five studies, 103 patients). In contrast, there was a significant effect of CPAP on the change (improvement) in insulin sensitivity (0.330, 95% CI=0.001, 0.658; P=0.049; three studies, 39 patients).

Conclusion:

The limited available evidence from randomised controlled trials and prospective observational studies suggests that CPAP does not decrease HbA1c level or BMI in patients with OSA and T2DM but may improve insulin sensitivity.

Biomarkers to improve diagnosis and monitoring of obstructive sleep apnea syndrome: current status and future perspectives

Obstructive sleep apnea syndrome (OSAS) is characterized by recurrent episodes of upper airway collapse associated with oxygen desaturation and sleep disruption. It is proposed that these periodic changes lead to molecular variations that can be detected by assessing serum biomarkers. Studies have identified inflammatory, oxidative, and metabolic perturbations attributable to sleep-disordered breathing. Given that OSAS is associated with increased cardiovascular and cerebrovascular morbidity, the ideal biomarker should enable timely recognition with the possibility of intervention. There is accumulating data on the utility of serum biomarkers for the evaluation of disease severity, prognosis, and response to treatment. However, current knowledge is limited by data collection techniques, disease complexity, and potential confounding factors. The current paper reviews the literature on the use of serum biomarkers in OSAS. It is concluded that the ideal serum biomarker still needs to be discovered, while caution is needed in the interpretation of hitherto available results.

Effect of continuous positive airway pressure on type 2 diabetes mellitus and glucose metabolism

BACKGROUND

Obstructive sleep apnea (OSA) is a prevalent condition that is associated with significant comorbidities, including obesity, hypertension, cardiovascular disease, and insulin resistance. Continuous positive airway pressure (CPAP) is an effective treatment for OSA. The effect of CPAP on glucose metabolism in patients with OSA has been controversial. This study evaluates the impact of CPAP on patients with OSA and type 2 diabetes mellitus (T2DM) or prediabetes.

MATERIALS AND METHODS

PubMed, Ovid Medline, and EMBASE were searched for original English language studies performed on or after 2003. Subjects were aged > 18 years, were diagnosed with OSA via polysomnography, and had either T2DM or prediabetes according to laboratory evaluation.

RESULTS

Of the 22 articles that met the selection criteria, 17 studies (77%) showed that a prolonged use of CPAP produced significant changes in glucose metabolism of patients who had T2DM and prediabetes. These changes were observed in studies measuring glycosylated hemoglobin (HbA1c), postprandial or nocturnal glucose, and insulin sensitivity or resistance. Of the 17 studies, 4 showed improvement in HbA1c levels or increased insulin sensitivity only after long-term use of CPAP for ≥ 3 months.

CONCLUSION

This literature review shows that CPAP improves not only hypoxia while restoring normal breathing during sleep, but also glucose metabolism in patients with OSA and T2DM or prediabetes. A few studies have shown that patients can experience even better results with long-term CPAP treatment (≥ 3 months of daily use) for > 4 hours a night. Therefore, this improvement in glucose metabolism with the use of CPAP may contribute to T2DM prevention and decrease further progression of the disease. However, additional studies are needed to confirm these findings.