The Association between Obstructive Sleep Apnea on Diabetic Kidney Disease: A Systematic Review and Meta-Analysis.

STUDY OBJECTIVE: This systematic review aims to investigate the association between obstructive sleep apnea (OSA) and diabetic kidney disease (DKD). METHODS: MeSH terms and free text searches were performed on MEDLINE, EMBASE, and Cochrane Database of Systematic Reviews from inception to April 2015. Zetoc and OpenGrey databases were queried for grey literature, and lastly, hand searches were carried out. Study selection and quality assessment were conducted by two authors. One author carried out data extraction, which was checked by other authors. The relationships between apneahypopnea index (AHI), oxygen desaturation index (ODI), time spent under 90% oxygen saturation (%TST < 90), and minimum and mean oxygen saturation (O2) on DKD were examined. RESULTS: Two longitudinal and ten cross-sectional studies were included for our narrative synthesis, and seven studies for meta-analysis. Studies that performed multi-variable analysis demonstrated significant associations between OSA (assessed using either apnea-hypopnea index or ODI) and DKD in type 2 diabetes mellitus (T2DM). This was confirmed by meta-analysis (pooled OR 1.73, 95% CI: 1.13-2.64). There was some evidence to suggest that %TST < 90 may have an association with DKD. There was insufficient evidence to conclude on the relationship between minimum and mean oxygen saturation on DKD. There was no evidence available on the associations between OSA and other respiratory parameters in type 1 diabetes mellitus populations. CONCLUSIONS: There is moderate evidence that OSA is associated with DKD in patients with T2DM. Large prospective studies with long-term follow up are needed to assess the possible bi-directional mechanisms between OSA and DKD.

The impact of hypoxemia on nephropathy in extremely obese patients with type 2 diabetes mellitus.

STUDY OBJECTIVES: Diabetes mellitus (DM) is associated with obstructive sleep apnea (OSA) and nephropathy. The hypoxemia associated with OSA may exacerbate renal deterioration in DM nephropathy. We examined the role of hypoxemia in the development of DM nephropathy in severely obese patients. METHODS: This cross-sectional study examined anonymized data from 90 DM patients with extreme obesity attending a weight management service. All patients underwent a routine overnight sleep study. Respiratory parameters measured included apnea-hypopnea index (AHI), mean and minimum oxygen (O2) saturations, and time spent under 90% O2 saturation (%TST < 90%). Chronic kidney disease (CKD+) was defined as estimated glomerular filtration rate (eGFR) ≤ 60 mL/min/1.73 m(2). RESULTS: Twenty (22%) patients were CKD+. These patients were 7 years older (mean age ± SD 57 ± 11 years, p = 0.003) and had greater adiposity (mean body mass index [BMI] ± SD 50.6 ± 8.7 kg/m(2), p = 0.012). No significant differences were found for median AHI and minimum O2 saturation. %TST < 90% was 4 times greater in CKD+ group (p = 0.046). Multivariate regression analysis showed that AHI (ß = -0.17, 95% CI: -0.316 to -0.024) and %TST < 90% (ß = -0.215, 95% CI: -0.406 to -0.023) were negatively correlated with eGFR after adjustment for age, gender, BMI, comorbidities, insulin treatment, and drugs affecting the renin-angiotensin system. No associations were found between mean and minimum O2 saturations, and eGFR. CONCLUSION: Apnea and hypopnea events as well as duration of nocturnal hypoxemia were inversely associated with renal function after adjusting for potential confounders. Given the significant burden of renal disease in diabetes, greater vigilance is required in identifying OSA in DM patients with extreme obesity.

Hypoxemia and glycemic control in type 2 diabetes mellitus with extreme obesity.

CONTEXT: Obstructive sleep apnea (OSA) has been shown to be associated with type 2 diabetes mellitus (DM). Studies on healthy individuals found that OSA is associated with lower insulin sensitivity. We hypothesized that nocturnal hypoxemia from OSA is associated with poorer glycemia in severely obese DM individuals. DESIGN AND SETTING: This was a retrospective observational study of 122 non-DM, 126 non-insulin-treated DM, and 35 insulin-treated DM patients. Data were collected on demographic characteristics, body mass index, and comorbidities. An overnight sleep study was performed in all patients, and OSA was defined as an apnea-hypopnea index of ≥5 events/h. RESULTS: There were more males (P = .003) and a lower proportion of white Europeans (P = .010) among DM patients. The prevalence of OSA was 80.1% in DM and 63.1% in non-DM individuals (P = .001). DM individuals also had lower oxygen saturation (O2) (P = .0106), greater percentage of time spent under 90% oxygen saturation (%TST<90%) (P = .0067), and higher apnea-hypopnea index (P = .0085). Regression analysis showed that %TST<90% and minimum O2 saturations were associated with worse hemoglobin A1c results among DM individuals. Every 10% reduction in minimum O2 was associated with a 0.3% increase in HbA1c, whereas a 10% increase in %TST<90% was associated with a 0.2% increase in hemoglobin A1c after adjusting for a range of potential confounders. CONCLUSION: The high OSA prevalence in DM individuals and a positive relationship between nocturnal hypoxemia and glycemia supports the need to assess correction of hypoxemia as a management strategy for glycemic control.

The potential association between obstructive sleep apnea and diabetic retinopathy in severe obesity-the role of hypoxemia.

BACKGROUND: Obstructive sleep apnea (OSA) is common in obese patients with type 2 diabetes mellitus (DM) and may contribute to diabetic microvascular complications. METHODS: To investigate the association between OSA, hypoxemia during sleep, and diabetic retinal complications in severe obesity. This was a prospective observational study of 93 obese patients mean (SD) age: 52(10) years; mean (SD) body mass index (BMI): 47.3(8.3) kg/m(2)) with DM undergoing retinal screening and respiratory monitoring during sleep. OSA was defined as apnea-hypopnea index (AHI) of ≥15 events/hour, resulting in two groups (OSA+ vs. OSA-). RESULTS: Forty-six patients were OSA+: median (95% CI) AHI = 37(23-74)/hour and 47 were OSA-ve (AHI = 7(4-11)/hour). Both groups were similar for ethnicity, BMI, cardiovascular co-morbidities, diabetes duration, HbA1c, and insulin treatment (p>0.05). The OSA+ group was significantly more hypoxemic. There was no significant difference between OSA+ and OSA- groups for the presence of retinopathy (39% vs. 38%). More OSA+ subjects had maculopathy (22% vs. 13%), but this did not reach statistical significance. Logistic regression analyses showed that AHI was not significantly associated with the presence of retinopathy or maculopathy (p>0.05). Whilst minimum oxygen saturation was not significantly associated with retinopathy, it was an independent predictor for the presence of maculopathy OR = 0.79 (95% CI: 0.65-0.95; p<0.05), after adjustment. CONCLUSIONS: The presence of OSA, as determined by AHI, was not associated with diabetic retinal complications. In contrast, severity of hypoxemia during sleep (minimum oxygen saturations) may be an important factor. The importance of hypoxia in the development of retinal complications in patients with OSA remains unclear and further studies assessing the pathogenesis of hypoxemia in patients with OSA and diabetic retinal disease are warranted.

The prevalence and severity of obstructive sleep apnea in severe obesity: the impact of ethnicity.

STUDY OBJECTIVES: The South Asian population is at increased risk of cardiovascular disease. We compared the prevalence and severity of obstructive sleep apnea (OSA) in South Asians and white Europeans with severe obesity. METHODS: Data from consecutive patients attending a specialist weight management service were analyzed. Self-reported age, gender, and ethnicity were recorded. Objective measurements of blood pressure, body mass index (BMI), and apneahypopnea index (AHI) were also acquired. RESULTS: A total of 308 patients (72.7% women; 13% South Asian) were included, with mean age and BMI of 46 ± 12 y and 49 ± 8 kg/m2, respectively. South Asians had significantly increased prevalence of OSA compared to white Europeans (85% vs. 66% [p = 0.017]) and were more likely to have severe OSA (42.5% vs. 21.6% [p = 0.015]). South Asians had significantly higher median AHI (24 events/h: interquartile range [IQR] 9.3-57.6 vs. 9 events/h: IQR 3.4-26.6; p < 0.01), significantly lower minimum oxygen saturation (76%: IQR 64% to 84% vs. 83%: IQR 77% to 87%; p < 0.01), and spent a significantly greater amount of time < 90% oxygen saturation (8.4%: IQR 1.0% to 24.3% vs. 2.4%: IQR 0.2% to 16.0%; p = 0.03). South Asian ethnicity, independent of demographics, BMI, and comorbidities, was associated with ß = 1.84 (95% CI: 1.27-2.65) increase in AHI+1 compared to white Europeans. Furthermore, we confirmed other independent OSA risk factors including increasing age, BMI, and male gender (all p < 0.001). CONCLUSIONS: Severely obese South Asians had significantly greater prevalence and severity of OSA than white Europeans. OSA may contribute to increased cardiovascular risk in South Asians compared to white Europeans with severe obesity. Mechanisms mediating the observed associations between these ethnicities require further investigation.

Secondary aorto-enteric fistula: a case report and review of literature.

Aorto-enteric fistula (AEF) is an uncommon but potentially fatal condition that is important to identify early because early diagnosis and aggressive management can reduce mortality. We report the case of a 73-year-old man with a history of aorto-bifemoral bypass grafting who was admitted for investigation of tiredness and lethargy. He passed melaena on the day of admission with an associated drop in haemoglobin. Initial upper gastrointestinal endoscopy revealed no significant abnormality. Later in the admission he again passed melaena, this time in large amounts. A repeat endoscopy identified a defect in the duodenal mucosa with visible Dacron graft. The patient went on to suffer another large bleed from which he could not be resuscitated. Our report highlights a fatal manifestation of aorto-enteric fistula, and reviews the associated literature.