Effect of CPAP on insulin resistance and HbA1c in men with obstructive sleep apnoea and type 2 diabetes
ABSTRACT The effects of continuous positive airway pressure (CPAP) for obstructive sleep apnoea (OSA) on insulin resistance are not clear. Trials have found conflicting results and no appropriate control groups have been used.
Forty-two men with known type 2 diabetes and newly diagnosed OSA (>10 dips/h in oxygen saturation of >4%) were randomised to receive therapeutic (n = 20) or placebo CPAP (n = 22) for 3 months. Baseline tests were performed and repeated after 3 months. The study was double blind.
Results are expressed as mean (SD). CPAP improved the Epworth sleepiness score significantly more in the therapeutic group than in the placebo group (-6.6 (4.5) vs -2.6 (4.9), p = 0.01). The maintenance of wakefulness test improved significantly in the therapeutic group but not in the placebo group (+10.6 (13.9) vs -4.7 (11.8) min, p = 0.001). Glycaemic control and insulin resistance did not significantly change in either the therapeutic or placebo groups: HbA1c (-0.02 (1.5) vs +0.1 (0.7), p = 0.7, 95% CI -0.6% to +0.9%), euglycaemic clamp (M/I: +1.7 (14.1) vs -5.7 (14.8), p = 0.2, 95% CI -1.8 to +0.3 l/kg/min(1000)), HOMA-%S (-1.5 (2.3) vs -1.1 (1.8), p = 0.2, 95% CI -0.3% to +0.08%) and adiponectin (-1.1 (1.2) vs -1.1 (1.3), p = 0.2, 95% CI -0.7 to +0.6 microg/ml). Body mass index, bioimpedance and anthropometric measurements were unchanged. Hours of CPAP use per night were 3.6 (2.8) in the treatment group and 3.3 (3.0) in the placebo group (p = 0.8). There was no correlation between CPAP use and the measures of glycaemic control or insulin resistance.
Therapeutic CPAP does not significantly improve measures of glycaemic control or insulin resistance in men with type 2 diabetes and OSA.
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ABSTRACT: 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. 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. 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. 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). 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.02/2015; 25:15005. DOI:10.1038/npjpcrm.2015.5
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ABSTRACT: OSA is a common chronic disorder that is associated with significant morbidity and mortality including cardiovascular, metabolic, and neurocognitive disease and increased cancer-related deaths. OSA is characterized by recurrent episodes of apneas and hypopneas associated with repetitive episodes of intermittent hypoxemia, intrathoracic pressure changes, and arousals. Intermittent hypoxemia (IH) is now being recognized as a potential major factor contributing to the pathogenesis of OSA-related comorbidities. OSA-related high-frequency IH is characterized by cycles of hypoxemia with reoxygenation that is distinctly different than sustained low-frequency hypoxia and contributes to ischemia-reperfusion injury. Data from both animal and human studies support mechanistic links between IH and its adverse impact at the tissue level. IH promotes oxidative stress by increased production of reactive oxygen species and angiogenesis, increased sympathetic activation with BP elevation, and systemic and vascular inflammation with endothelial dysfunction that contributes to diverse multiorgan chronic morbidity and mortality affecting cardiovascular disease, metabolic dysfunction, cognitive decline, and progression of cancer. Data from observational studies in large population groups also support the role for hypoxia in the pathogenesis of OSA comorbidity. Treatment with CPAP to reverse OSA-related symptoms and comorbidities has been shown to provide variable benefit in some but not all patient groups. Early treatment with CPAP makes intuitive sense to promote maximal functional recovery and minimize residual injury. More studies are needed to determine the interacting effects of IH and obesity, differential effects of both short-term and long-term hypoxemia, and the effect of CPAP treatment.Chest 01/2015; 147(1):266-74. DOI:10.1378/chest.14-0500 · 7.13 Impact Factor
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ABSTRACT: We sought to conduct an updated meta-analysis of randomized controlled trials (RCTs) on the effect of continuous positive airway pressure (CPAP) on insulin resistance, as measured by homeostasis model assessment of insulin resistance (HOMA-IR), visceral abdominal fat (VAF), and adiponectin. Additionally, we performed a separate meta-analysis and meta-regression of studies on the association of insulin resistance and obstructive sleep apnea (OSA). All included studies were searched from PubMed (from conception to March 15, 2014). Data were pooled across all included RCTs as the mean difference in HOMA-IR and VAF, and as the standardized mean difference in the case of adiponectin analysis. From the included case-control studies, data on the difference of HOMA-IR between cases and controls were pooled across all studies, as the standardized mean difference (SMD). There was a significant difference in HOMA-IR (-0.43 [95% CIs: -0.75 to -0.11], p = 0.008) between CPAP treated and non CPAP treated participants. However, there was no significant difference in VAF or adiponectin; (-47.93 [95% CI: -112.58 to 16.72], p = 0.14) and (-0.06 [95% CI: -0.28 to 0.15], p = 0.56), respectively. Meta-analysis of 16 case-control studies showed a pooled SMD in HOMA-IR of 0.51 (95% CI: 0.28 to 0.75), p ≤ 0.001, between cases and controls. The results of our meta-analyses show that CPAP has a favorable effect on insulin resistance. This effect is not associated with any significant changes in total adiponectin levels or amount of VAF. Our findings also confirm a significant association between OSA and insulin resistance. © 2015 American Academy of Sleep Medicine.Journal of clinical sleep medicine: JCSM: official publication of the American Academy of Sleep Medicine 12/2014; DOI:10.5664/jcsm.4610 · 2.83 Impact Factor