The Relationship between Diabetic Neuropathy and Sleep Apnea Syndrome: A Meta-Analysis

A Comprehensive Analysis of Clinical, Biochemical, and Polysomnographic Characteristics in Patients With Type 2 Diabetes Mellitus With and Without Obstructive Sleep Apnea

BACKGROUND

Obstructive sleep apnea (OSA) has been a significant contributor to mortality all across the globe. The most attributing factors to pathogenesis are metabolic syndrome, obesity, diabetes, and so on, but the indicators of its early detection are still elusive.

OBJECTIVE

The study aimed to compare the clinical, biochemical, and polysomnographic characteristics of type 2 diabetes patients with and without OSA.

DESIGN AND METHODS

This cross-sectional study was conducted at the Department of Medicine and Endocrinology Unit of Dayanand Medical College and Hospital, Ludhiana. A total of 584 patients with type 2 diabetes were assessed using the Berlin questionnaire, with 302 fulfilling the criteria for a high risk of OSA. Out of 302 patients who met the criteria for the high-risk category, 110 patients underwent a sleep study.

RESULTS

 Three hundred and two patients satisfying the inclusion and exclusion criteria were enrolled in the study. A total of 110 patients underwent a sleep study, of which 68 (61.8%) had evidence of OSA. The waist-to-hip ratio was considerably higher in the OSA patients than in the non-OSA group (1.09 vs 0.930, p = 0.001). HbA1c >7% was found in 58.8% of OSA patients contrary to 38.1% of non-OSA patients. Fasting plasma glucose levels (>126 mg/dl) were identified in a substantially larger proportion of OSA patients than the non-OSA patients (64.7% vs 45.2%, p = 0.04). Similarly, peripheral neuropathy was found more commonly in the OSA patients than in the non-OSA patients (47% vs. 26.1%, p = 0.02). Prevalence of retinopathy, nephropathy, coronary artery disease, stroke, heart failure, and peripheral vascular disease did not differ significantly between the two groups.

CONCLUSIONS

OSA frequently occurs among individuals diagnosed with type 2 diabetes mellitus. The prompt identification of OSA within this demographic is imperative to pinpoint those at an elevated risk of succumbing to conditions such as peripheral neuropathy, the exacerbation of glycemic control, and the onset of unmanaged hypertension. Moreover, there exists a positive correlation between the waist-to-hip ratio and the prevalence of OSA in persons with type 2 diabetes mellitus, highlighting the critical role of waist-to-hip ratio assessments in this patient population.

Sleep dysregulation in sympathetic-mediated diseases: implications for disease progression

The autonomic nervous system (ANS) plays an important role in the coordination of several physiological functions including sleep/wake process. Significant changes in ANS activity occur during wake-to-sleep transition maintaining the adequate cardiorespiratory regulation and brain activity. Since sleep is a complex homeostatic function, partly regulated by the ANS, it is not surprising that sleep disruption trigger and/or evidence symptoms of ANS impairment. Indeed, several studies suggest a bidirectional relationship between impaired ANS function (i.e. enhanced sympathetic drive), and the emergence/development of sleep disorders. Furthermore, several epidemiological studies described a strong association between sympathetic-mediated diseases and the development and maintenance of sleep disorders resulting in a vicious cycle with adverse outcomes and increased mortality risk. However, which and how the sleep/wake control and ANS circuitry becomes affected during the progression of ANS-related diseases remains poorly understood. Thus, understanding the physiological mechanisms underpinning sleep/wake-dependent sympathetic modulation could provide insights into diseases involving autonomic dysfunction. The purpose of this review is to explore potential neural mechanisms involved in both the onset/maintenance of sympathetic-mediated diseases (Rett syndrome, congenital central hypoventilation syndrome, obstructive sleep apnoea, type 2 diabetes, obesity, heart failure, hypertension, and neurodegenerative diseases) and their plausible contribution to the generation of sleep disorders in order to review evidence that may serve to establish a causal link between sleep disorders and heightened sympathetic activity.

Does Obstructive Sleep Apnoea Syndrome Influence the Development and Treatment of Diabetic Foot? A Brief Narrative Review

Both obstructive sleep apnoea syndrome (OSAS) and diabetes mellitus (DM) are common conditions that often coexist and share many similar risk factors. Diabetic foot is a common complication of DM, which may lead to lower-limb amputation. OSAS is considered a risk factor for type 2 DM (T2DM). There is also evidence that OSAS may be linked with the development, as well as the healing of diabetic foot. Multiple mechanisms triggered by sleep fragmentation and intermittent hypoxaemia in OSAS could contribute to the development of diabetic foot ulcers (DFUs). More interestingly, emerging evidence implies a favourable impact of continuous positive airway pressure (CPAP) treatment on DFU healing. Healing DFUs and minimising recurrence rates remains a challenge for health care professionals. In this context, management of OSAS might prove a useful therapeutic adjunct for DFUS. However, data is still limited and randomised controlled trials are needed to further explore this interesting potential.

Advances in the study of OSA and diabetic foot

Diabetic foot is one of the most serious and painful chronic complications of diabetic patients, especially elderly diabetic patients. It has a high rate of death, disability and amputation. Obstructive sleep apnea (OSA) is a treatable chronic sleep disorder. Existing evidence suggests that OSA may promote the development and delay the healing of diabetic foot, and continuous positive airway pressure therapy may promote the healing of ulcers. Therefore, in the multidisciplinary diagnosis and treatment of diabetes, cooperation with sleep medicine should be strengthened, and the basic and clinical research on diabetic foot combined with OSA should be strengthened, so as to reduce the amputation rate, improve the cure rate and reduce the incidence of cardiovascular events.

Possible Preventative/Rehabilitative Role of Gliflozins in OSA and T2DM. A Systematic Literature Review-Based Hypothesis

Obstructive sleep apnoea (OSA) is characterized by frequent apnoea episodes during sleep due to upper airway obstruction. The present review summarizes current knowledge on inter-relationships between OSA and type 2 diabetes mellitus (T2DM) and suggests the former as a possible target for sodium-glucose co-transporter-2 inhibitors (SGLT-2i). Based on pathophysiological mechanisms underlying OSA onset and renal SGLT-2 effects, we suggest that SGLT-2i indications might expand beyond current ones, including glucose, lipids, uric acid, blood pressure, and body weight control as well as chronic heart failure and kidney disease prevention.

Deterioration of Sleep Quality According to Glycemic Status

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a progressive disease with multiple complications. The present study aimed to determine the effects of glycemic status on sleep quality in individuals with T2DM, prediabetes, and normal glucose tolerance (NGT).

METHODS

A total of 90 participants were categorized into three groups, T2DM (n=30), prediabetes (n=30), and NGT (n=30). Objective sleep quality was measured with the actigraph wrist-worn device over 3 nights and subjective sleep quality was evaluated with a questionnaire.

RESULTS

The duration of diabetes in the T2DM group was 2.23 years and the glycosylated hemoglobin (HbA1c) levels in the T2DM, prediabetes, and NGT groups were 7.83%, 5.80%, and 5.31%, respectively. Sleep efficiency decreased across the T2DM, prediabetes, and NGT groups (86.25%, 87.99%, and 90.22%, respectively; P=0.047). Additionally, HbA1c levels revealed a significant negative correlation with sleep efficiency (r=-0.348, P=0.001). The sleep quality questionnaire results were similar among the three groups.

CONCLUSION

Although the participants in the present study were not necessarily conscious of their sleep disturbances, deterioration in sleep quality progressed according to glycemic status.

Impact of sleep apnoea-hypopnoea syndrome on diabetic neuropathy. A systematic review

INTRODUCTION

Diabetes mellitus and sleep apnoea-hypopnoea syndrome appear to be related, but it is not well defined whether there is an increased risk of peripheral neuropathy in patients with both diseases. For this reason, we conducted a systematic review.

METHODS

Bibliographic search in 3 electronic databases using a predefined strategy and the PRISMA methodology. Only original studies (any type of design) published from 2000 onwards in English, French, Portuguese or Spanish were included. A study quality scale was established.

RESULTS

Twelve articles were selected, of which six studied type 2 diabetic patients. The overall prevalence of sleep apnoea-hypopnoea syndrome was 43.7% (1,559/3,564 patients). Diabetic neuropathy was more frequent in patients with sleep apnoea-hypopnoea syndrome in nine studies, although significantly only in four (60% vs 27%, P<.001; 64.5% vs 36%, P=.03; 37% vs 23.4%, P<.02; 66.6% vs 0%, P=.007). In one study, diabetic neuropathy was more frequent in patients without sleep apnoea-hypopnoea syndrome (although not statistically significant) and in 2 no comparison was made between patients with/without sleep apnoea/hypopnoea syndrome.

CONCLUSIONS

The observed results suggest a relationship between diabetes mellitus and sleep apnoea-hypopnoea syndrome in the occurrence of diabetic neuropathy.

The association between sleep and diabetes outcomes - A systematic review

AIM

This study aimed to systematically review the prevalence of diagnosed sleep disorders in people with diabetes and to determine the association between sleep disorders and blood glucose levels and diabetes outcomes.

METHODS

We conducted a literature search in the following databases: MEDLINE (Pubmed), EMBASE, CINAHL, PsychInfo and Web of Science Citation Index. Meta-analysis (random-effects models) was conducted to estimate the prevalence of sleep disorders in people with diabetes.

RESULTS

Forty-one articles measured the prevalence of sleep disorders in adults with diabetes. The estimated pooled prevalence of sleep disorders in diabetes was estimated to be 52% (95% CI 42-63%). The highest pooled prevalence was observed for unspecified sleep apnea (69%; 95% CI: 59-78%), followed by obstructive sleep apnea (60%; 95% CI 39-80%), and restless leg syndrome (27%; 95% CI 20-34%). Eleven studies examined the association between sleep disorders and diabetes control and complications. The presence of comorbid sleep disorders was associated with increased diabetes outcomes.

CONCLUSIONS

Diagnosed sleep disorders are highly prevalent in people with diabetes. Sleep disorders are associated with diabetes outcomes, though there was considerable heterogeneity across studies.

Sleep duration is a significant predictor of cardiac autonomic neuropathy in type 2 diabetes mellitus

AIM

To investigate the association between sleep quality outcomes and measures of cardiac autonomic function and to assess the predictive ability of sleep quality outcomes for cardiac autonomic neuropathy (CAN) in type 2 diabetes mellitus (T2DM).

METHODS

Fifty patients with T2DM (age, 51.3±7.01years; glycemic control, 8.4±1.65%) completed the study. Patients were diagnosed for CAN using the standard clinical autonomic test battery and were also assessed for heart rate variability (HRV) under resting conditions. Sleep quality was examined using the Pittsburg Sleep Quality Index (PSQI).

RESULTS

Sleep duration, sleep onset latency, sleep efficiency, daytime dysfunction and global PSQI score showed significant correlations with measures of cardiac autonomic control (p<0.05). At an optimal cut-off of≤5.83h (area under the curve: 0.76, p=0.0003; sensitivity: 50%; specificity: 94.4%), sleep duration predicted occurrence of CAN (odds ratio, confidence interval: 0.18, 0.04-0.70; p=0.01) in T2DM after adjusting for various clinical confounders.

CONCLUSION

Findings of the present study suggest that subjective sleep outcomes such as sleep duration, sleep onset latency, sleep efficiency, daytime dysfunction and overall sleep quality are associated with the indices of cardiac autonomic function in T2DM. Moreover, short sleep duration may be considered a predictor in the occurrence of CAN in these patients. Considering the role of sleep in the pathophysiology of CAN, sleep should be routinely examined in patients with T2DM and appropriate therapeutic interventions should be implemented particularly in case of reduced sleep duration.

The correlation between obstructive sleep apnea and diabetic neuropathy: A meta-analysis

BACKGROUND

The aim of this study was to explore the correlation between obstructive sleep apnea (OSA) and diabetic neuropathy.

MATERIALS AND METHODS

After working out searching strategy, literatures were screened from the electronic databases: PubMed, Embase, and the Cochrane library. R 3.12 was utilized to perform meta-analysis, and odds ratio (OR) and its 95% confidence interval (CI) were used to present effect size. Heterogeneity was assessed by χ²-based Q test and I² statistics. Publication bias was estimated by Egger's test and sensitivity was evaluated by leave one out methods.

RESULTS

According to the criteria, a total of 11 studies with 1842 patients were enrolled in this study. With a significant heterogeneity (Q=31.83, I²=68.60%), the random effects model was utilized to assess the effect size of pooled data. A remarkable correlation was identified OSA and diabetic neuropathy (OR=1.84, 95% CI: 1.18-2.87) without publication bias (t=1.68, P=0.13). Meanwhile, the result of leave one out performed a well sensitivity. Moreover, the subgroup analyses presented that OSA was significantly correlated with type 1 diabetic neuropathy (OR=1.97, 95% CI: 1.19-3.25), but no remarkable correlation was identified between OSA and type 1 (OR=1.84, 95% CI: 0.86-3.93) or 1+2 (OR=1.30, 95% CI: 0.43-3.92) diabetic neuropathy.

CONCLUSION

OSA was significantly correlated with neuropathy in type 1 diabetes, but not in type 2 and type 1+2 diabetes.

The Relationship between Diabetes-Related Complications and Obstructive Sleep Apnea in Type 2 Diabetes

This study explored the relationship between obstructive sleep apnea (OSA) and the presence of any diabetes-related complications in type 2 diabetes and whether this was mediated by hypertension. Secondly, the relationship between OSA severity and estimated glomerular filtration rate (eGFR) was investigated. A total of 131 patients participated. OSA was diagnosed using a home monitor, and severity was measured by apnea-hypopnea index (AHI) and oxygen desaturation index (ODI). OSA was found in 75.6% of the participants, 40.5% with moderate-to-severe degree. Any diabetes-related complications (retinopathy, neuropathy, nephropathy, or coronary artery disease) were present in 55.5%, and 70.2% of the participants had hypertension. Mediation analysis indicated that, compared to those with mild or no OSA, those with moderate-to-severe OSA were 3.05 times more likely to have any diabetes-related complications and that this relationship was mediated by the presence of hypertension. After adjusting for confounders, ODI (B = -0.036, p = 0.041), but not AHI, was significantly associated with lower eGFR. In conclusion, moderate-to-severe OSA was related to the presence of any diabetes-related complications in type 2 diabetes, and the relationship was mediated by hypertension. The severity of intermittent hypoxia was associated with lower eGFR. Whether OSA treatment will delay or reduce diabetes-related complications should be investigated.

Interactions between and Shared Molecular Mechanisms of Diabetic Peripheral Neuropathy and Obstructive Sleep Apnea in Type 2 Diabetes Patients

Type 2 diabetes (T2D) accounts for about 90% of all diabetes patients and incurs a heavy global public health burden. Up to 50% of T2D patients will eventually develop neuropathy as T2D progresses. Diabetic peripheral neuropathy (DPN) is a common diabetic complication and one of the main causes of increased morbidity and mortality of T2D patients. Obstructive sleep apnea (OSA) affects over 15% of the general population and is associated with a higher prevalence of T2D. Growing evidence also indicates that OSA is highly prevalent in T2D patients probably due to diabetic peripheral neuropathy. However, the interrelations among diabetic peripheral neuropathy, OSA, and T2D hitherto have not been clearly elucidated. Numerous molecular mechanisms have been documented that underlie diabetic peripheral neuropathy and OSA, including oxidative stress, inflammation, endothelin-1, vascular endothelial growth factor (VEGF), accumulation of advanced glycation end products, protein kinase C (PKC) signaling, poly ADP ribose polymerase (PARP), nitrosative stress, plasminogen activator inhibitor-1, and vitamin D deficiency. In this review, we seek to illuminate the relationships among T2D, diabetic peripheral neuropathy, and OSA and how they interact with one another. In addition, we summarize and explain the shared molecular mechanisms involved in diabetic peripheral neuropathy and OSA for further mechanistic investigations and novel therapeutic strategies for attenuating and preventing the development and progression of diabetic peripheral neuropathy and OSA in T2D.

Risk Factors and Comorbidities in Diabetic Neuropathy: An Update 2015

Distal symmetric sensorimotor polyneuropathy (DSPN) is the most common neurological manifestation in diabetes. Major risk factors of DSPN include diabetes duration, hyperglycemia, and age, followed by prediabetes, hypertension, dyslipidemia, and obesity. Height, smoking, insulin resistance, hypoinsulinemia, and others represent an additional risk. Importantly, hyperglycemia, hypertension, dyslipidemia, obesity, and smoking are modifiable. Stringent glycemic control has been shown to be effective in type 1, but not to the same extent in type 2 diabetes. Antilipidemic treatment, especially with fenofibrate, and multi-factorial intervention have produced encouraging results, but more experience is necessary. The major comorbidities of DSPN are depression, autonomic neuropathy, peripheral arterial disease, cardiovascular disease, nephropathy, retinopathy, and medial arterial calcification. Knowledge of risk factors and comorbidities has the potential to enrich the therapeutic strategy in clinical practice as part of the overall medical care for patients with neuropathy. This article provides an updated overview of DSPN risk factors and comorbidities.

The Relationship between Metformin and Obstructive Sleep Apnea

OBJECTIVES

This study aimed to assess if metformin had any associations with the prevalence of obstructive sleep apnea in an adult type 2 diabetes population in the Midwest.

HYPOTHESIS

Use of metformin is associated with decreased prevalence of obstructive sleep apnea in a adult type 2 diabetes population.

METHODS

A retrospective secondary database analysis was carried out with metformin use by patients with type 2 diabetes as the primary variable of interest and obstructive sleep apnea status as the primary outcome. A sample population of 9,853 type 2 diabetes patients with one year of follow-up was used. Other variables that were analyzed included age, gender, race, hypertension, Congestive Heart Failure, Hemoglobin A1c (HbA1c), and Body Mass Index. A p-value of <0.01 was considered significant.

RESULTS

Metformin usage was not significantly associated with obstructive sleep apnea prevalence (Odds Ratio: 1.17, Confidence Interval: 1.00-1.36, p = 0.049), but trended in the direction where metformin usage was associated with having obstructive sleep apnea. Lower HbA1c was found to be significantly associated with lower prevalence of obstructive sleep apnea (p <0.001). The rest of the variables followed previously published associations.

CONCLUSIONS

Metformin therapy may improve sleep quality, but it may not be through methods that reduce the likelihood of developing obstructive sleep apnea. Future studies that can prove causation about this association should be considered.

Sleep apnea-hypopnea syndrome and type 2 diabetes. A reciprocal relationship?

Epidemiological data suggest that sleep apnea-hypopnea syndrome (SAHS) is independently associated with the development of insulin resistance and glucose intolerance. Moreover, despite significant methodological limitations, some studies report a high prevalence of SAHS in patients with type 2 diabetes mellitus (DM2). A recent meta-analysis shows that moderate-severe SAHS is associated with an increased risk of DM2 (relative risk=1.63 [1.09 to 2.45]), compared to the absence of apneas and hypopneas. Common alterations in various pathogenic pathways add biological plausibility to this relationship. Intermittent hypoxia and sleep fragmentation, caused by successive apnea-hypopnea episodes, induce several intermediate disorders, such as activation of the sympathetic nervous system, oxidative stress, systemic inflammation, alterations in appetite-regulating hormones and activation of the hypothalamic-pituitary-adrenal axis which, in turn, favor the development of insulin resistance, its progression to glucose intolerance and, ultimately, to DM2. Concomitant SAHS seems to increase DM2 severity, since it worsens glycemic control and enhances the effects of atherosclerosis on the development of macrovascular complications. Furthermore, SAHS may be associated with the development of microvascular complications: retinopathy, nephropathy or diabetic neuropathy in particular. Data are still scant, but it seems that DM2 may also worsen SAHS progression, by increasing the collapsibility of the upper airway and the development of central apneas and hypopneas.

Autonomic neuropathy in diabetes mellitus

Diabetic autonomic neuropathy (DAN) is a serious and common complication of diabetes, often overlooked and misdiagnosed. It is a systemic-wide disorder that may be asymptomatic in the early stages. The most studied and clinically important form of DAN is cardiovascular autonomic neuropathy defined as the impairment of autonomic control of the cardiovascular system in patients with diabetes after exclusion of other causes. The reported prevalence of DAN varies widely depending on inconsistent definition, different diagnostic method, different patient cohorts studied. The pathogenesis is still unclear and probably multifactorial. Once DAN becomes clinically evident, no form of therapy has been identified, which can effectively stop or reverse it. Prevention strategies are based on strict glycemic control with intensive insulin treatment, multifactorial intervention, and lifestyle modification including control of hypertension, dyslipidemia, stop smoking, weight loss, and adequate physical exercise. The present review summarizes the latest knowledge regarding clinical presentation, epidemiology, pathogenesis, and management of DAN, with some mention to childhood and adolescent population.