Predictors of improvement and progression of diabetic polyneuropathy following treatment with α-lipoic acid for 4 years in the NATHAN 1 trial

Efficacy and Safety of the Combination of Palmitoylethanolamide, Superoxide Dismutase, Alpha Lipoic Acid, Vitamins B12, B1, B6, E, Mg, Zn and Nicotinamide for 6 Months in People with Diabetic Neuropathy

AIM

To investigate the efficacy of Palmitoylethanolamide (PEA, 300 mg), Superoxide Dismutase (SOD, 70 UI), Alpha Lipoic Acid (ALA, 300 mg), vitamins B6 (1.5 mg), B1 (1.1 mg), B12 (2.5 mcg), E (7.5 mg), nicotinamide (9 mg), and minerals (Mg 30 mg, Zn 2.5 mg) in one tablet in people with Diabetic Neuropathy (DN).

PATIENTS-METHODS

In the present pilot study, 73 people (age 63.0 ± 9.9 years, 37 women) with type 2 Diabetes Mellitus (DMT2) (duration 17.5 ± 7.3 years) and DN were randomly assigned to receive either the combination of ten elements (2 tablets/24 h) in the active group (n = 36) or the placebo (n = 37) for 6 months. We used the Michigan Neuropathy Screening Instrument Questionnaire and Examination (MNSIQ and MNSIE), measured vibration perception threshold (VPT) with biothesiometer, and Cardiovascular Autonomic Reflex Tests (CARTs). Nerve function was assessed by DPN Check [sural nerve conduction velocity (SNCV) and amplitude (SNAP)]. Sudomotor function was assessed with SUDOSCAN, which measures electrochemical skin conductance in hands and feet (ESCH and ESCF). Pain score (PS) was assessed with Pain DETECT questionnaire. Quality of life was assessed by questionnaire.

RESULTS

In the active group, there was a large improvement of pain (PS from 20.9 to 13.9, p < 0.001). There was also a significant improvement of vitamin B12 (B12) levels, MNSIQ, SNCV, VPT, and ESCF (222.1 vs. 576.3 pg/ mL, p < 0.001; 6.1 vs. 5.9, p = 0.017; 28.8 vs. 30.4, p = 0.001; 32.1 vs. 26.7, p = 0.001; and 72.2 vs. 74.8, p < 0.001 respectively). In the placebo group, neither pain (21.6 vs. 21.7, p = 0.870) or any other aforementioned parameters changed significantly, and MNSIE worsened (2.9 vs. 3.4, p < 0.001). As a result, changes from baseline to follow-up in pain, B12 levels, VPT, and MNSIQ differed significantly between the two groups (p < 0.001, 0.025, 0.009, and <0.001, respectively). CARTs, SNAP, ESCH did not significantly change in either of the two groups.

CONCLUSIONS

The combination of the ten elements in one tablet for 6 months at a daily dose of two tablets in people with DN significantly improves pain, vibration perception threshold, and B12 levels.

Expert opinion on screening, diagnosis and management of diabetic peripheral neuropathy: a multidisciplinary approach

The proposed expert opinion aimed to address the current knowledge on conceptual, clinical, and therapeutic aspects of diabetic peripheral neuropathy (DPN) and to provide a guidance document to assist clinicians for the best practice in DPN care. The participating experts consider the suspicion of the disease by clinicians as a key factor in early recognition and diagnosis, emphasizing an improved awareness of the disease by the first-admission or referring physicians. The proposed "screening and diagnostic" algorithm involves the consideration of DPN in a patient with prediabetes or diabetes who presents with neuropathic symptoms and/or signs of neuropathy in the presence of DPN risk factors, with careful consideration of laboratory testing to rule out other causes of distal symmetric peripheral neuropathy and referral for a detailed neurological work-up for a confirmative test of either small or large nerve fiber dysfunction in atypical cases. Although, the first-line interventions for DPN are currently represented by optimized glycemic control (mainly for type 1 diabetes) and multifactorial intervention (mainly for type 2 diabetes), there is a need for individualized pathogenesis-directed treatment approaches for DPN. Alpha-lipoic acid (ALA) seems to be an important first-line pathogenesis-directed agent, given that it is a direct and indirect antioxidant that works with a strategy targeted directly against reactive oxygen species and indirectly in favor of endogenous antioxidant capacity for improving DPN conditions. There is still a gap in existing research in the field, necessitating well-designed, robust, multicenter clinical trials with sensitive endpoints and standardized protocols to facilitate the diagnosis of DPN via a simple and effective algorithm and to track progression of disease and treatment response. Identification of biomarkers/predictors that would allow an individualized approach from a potentially disease-modifying perspective may provide opportunities for novel treatments that would be efficacious in early stages of DPN, and may modify the natural course of the disease. This expert opinion document is expected to increase awareness among physicians about conceptual, clinical, and therapeutic aspects of DPN and to assist them in timely recognition of DPN and translating this information into their clinical practice for best practice in the management of patients with DPN.

Cardiac Autonomic Neuropathy in Prediabetes: A Case-Control Study

Introduction

Early detection and diagnosis of diabetic autonomic neuropathy, especially cardiac autonomic neuropathy (CAN), have gained attention recently because of their elevated cardiovascular mortality risk. Although the connection between type 2 diabetes mellitus and autonomic neuropathy is well established, evidence is emerging that the association might predate the stage of prediabetes.

Objective

The present study was undertaken to compare the prevalence of CAN in prediabetes versus that in normoglycemic controls.

Materials and Methods

The study population was selected by purposive sampling from individuals attending a tertiary care hospital from January 2018 to June 2019. Fifty individuals with prediabetes diagnosed by the American Diabetes Association's glycated haemoglobin criteria and 50 age- and gender-matched healthy controls were recruited. CAN was assessed by standard cardiovascular reflex tests, as described by Ewing and Clarke. Changes in R-R with deep breathing, Valsalva manoeuver, and changes in blood pressure (BP) in response to standing and sustained handgrip were evaluated. Three-time domains [standard deviation of normal-to-normal intervals (SDNN), root mean square of successive RR intervals (rMSSD) and percentage of successive normal to normal R-R (NN) intervals that differ by more than 50 ms (pNN50)] and four frequency domain indices [very low-frequency band (VLF), low-frequency band (LF), high-frequency band (HF), LF/HF ratio) of heart rate variability (HRV)] were examined.

Results

The mean heart rate was 71.37 ± 7.94 and 65.59 ± 8.73 beats/min in patients with prediabetes and controls, respectively (P < 0.05). All three-time-domain indices of HRV were significantly lower in persons with prediabetes compared to controls. The peak frequency of LF, peak power of LF, normalised unit of LF, and LF/HF ratio was significantly lower in subjects with prediabetes than in controls. There was no difference in the traditional cardiovascular autonomic reflex testing.

Conclusion

Our study demonstrates the presence of subclinical autonomic dysfunction in persons with prediabetes. Early detection of CAN in prediabetes can have future implications for cardiovascular risk reduction.

Chemoproteomic target deconvolution reveals Histone Deacetylases as targets of (R)-lipoic acid

Lipoic acid is an essential enzyme cofactor in central metabolic pathways. Due to its claimed antioxidant properties, racemic (R/S)-lipoic acid is used as a food supplement but is also investigated as a pharmaceutical in over 180 clinical trials covering a broad range of diseases. Moreover, (R/S)-lipoic acid is an approved drug for the treatment of diabetic neuropathy. However, its mechanism of action remains elusive. Here, we performed chemoproteomics-aided target deconvolution of lipoic acid and its active close analog lipoamide. We find that histone deacetylases HDAC1, HDAC2, HDAC3, HDAC6, HDAC8, and HDAC10 are molecular targets of the reduced form of lipoic acid and lipoamide. Importantly, only the naturally occurring (R)-enantiomer inhibits HDACs at physiologically relevant concentrations and leads to hyperacetylation of HDAC substrates. The inhibition of HDACs by (R)-lipoic acid and lipoamide explain why both compounds prevent stress granule formation in cells and may also provide a molecular rationale for many other phenotypic effects elicited by lipoic acid.

Molecular and Therapeutic Insights of Alpha-Lipoic Acid as a Potential Molecule for Disease Prevention

Alpha-lipoic acid is an organic, sulfate-based compound produced by plants, humans, and animals. As a potent antioxidant and a natural dithiol compound, it performs a crucial role in mitochondrial bioenergetic reactions. A healthy human body, on the other hand, can synthesize enough α-lipoic acid to scavenge reactive oxygen species and increase endogenous antioxidants; however, the amount of α-lipoic acid inside the body decreases significantly with age, resulting in endothelial dysfunction. Molecular orbital energy and spin density analysis indicate that the sulfhydryl (-SH) group of molecules has the greatest electron donating activity, which would be responsible for the antioxidant potential and free radical scavenging activity. α-Lipoic acid acts as a chelating agent for metal ions, a quenching agent for reactive oxygen species, and a reducing agent for the oxidized form of glutathione and vitamins C and E. α-Lipoic acid enantiomers and its reduced form have antioxidant, cognitive, cardiovascular, detoxifying, anti-aging, dietary supplement, anti-cancer, neuroprotective, antimicrobial, and anti-inflammatory properties. α-Lipoic acid has cytotoxic and antiproliferative effects on several cancers, including polycystic ovarian syndrome. It also has usefulness in the context of female and male infertility. Although α-lipoic acid has numerous clinical applications, the majority of them stem from its antioxidant properties; however, its bioavailability in its pure form is low (approximately 30%). However, nanoformulations have shown promise in this regard. The proton affinity and electron donating activity, as a redox-active agent, would be responsible for the antioxidant potential and free radical scavenging activity of the molecule. This review discusses the most recent clinical data on α-lipoic acid in the prevention, management, and treatment of a variety of diseases, including coronavirus disease 2019. Based on current evidence, the preclinical and clinical potential of this molecule is discussed.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s43450-023-00370-1.

Nutraceutical Prevention of Diabetic Complications—Focus on Dicarbonyl and Oxidative Stress

Oxidative and dicarbonyl stress, driven by excess accumulation of glycolytic intermediates in cells that are highly permeable to glucose in the absence of effective insulin activity, appear to be the chief mediators of the complications of diabetes. The most pathogenically significant dicarbonyl stress reflects spontaneous dephosphorylation of glycolytic triose phosphates, giving rise to highly reactive methylglyoxal. This compound can be converted to harmless lactate by the sequential activity of glyoxalase I and II, employing glutathione as a catalyst. The transcription of glyoxalase I, rate-limiting for this process, is promoted by Nrf2, which can be activated by nutraceutical phase 2 inducers such as lipoic acid and sulforaphane. In cells exposed to hyperglycemia, glycine somehow up-regulates Nrf2 activity. Zinc can likewise promote glyoxalase I transcription, via activation of the metal-responsive transcription factor (MTF) that binds to the glyoxalase promoter. Induction of glyoxalase I and metallothionein may explain the protective impact of zinc in rodent models of diabetic complications. With respect to the contribution of oxidative stress to diabetic complications, promoters of mitophagy and mitochondrial biogenesis, UCP2 inducers, inhibitors of NAPDH oxidase, recouplers of eNOS, glutathione precursors, membrane oxidant scavengers, Nrf2 activators, and correction of diabetic thiamine deficiency should help to quell this.

Alpha-lipoic acid treatment improves adverse cardiac remodelling in the diabetic heart - The role of cardiac hydrogen sulfide-synthesizing enzymes

INTRODUCTION

Alpha-lipoic acid (ALA) is a licensed drug for the treatment of diabetic neuropathy. We recently reported that it also improves diabetic cardiomyopathy (DCM) in type 2 diabetes mellitus (T2DM). In this study, we present evidence supporting our hypothesis that the cardioprotective effect of ALA is via upregulation of cardiac hydrogen sulfide (H₂S)-synthesizing enzymes.

METHODS

Following 12 h of overnight fasting, T2DM was induced in 23 out of 30 male Sprague-Dawley rats by intraperitoneal administration of nicotinamide (110 mg/kg) followed by streptozotocin (55 mg/kg) while the rest served as healthy control (HC). T2DM rats then received either oral administration of ALA (60 mg/kg/day; n = 7) or 40 mg/kg/day DL-propargylglycine (PAG, an endogenous H₂S inhibitor; n = 7) intraperitoneally for 6 weeks after which all rats were sacrificed and samples collected for analysis. Untreated T2DM rats served as diabetic control (DCM; n = 9).

RESULTS

T2DM resulted in weight loss, islet destruction, reduced pancreatic β-cell function and hyperglycemia. Histologically, DCM rats showed significant myocardial damage evidenced by myocardial degeneration, cardiomyocyte vacuolation and apoptosis, cardiac fibrosis and inflammation, which positively correlated with elevated levels of cardiac damage markers compared to HC rats (p < 0.001). These pathological alterations worsened significantly in PAG-treated rats (p < 0.05). However, ALA treatment restored normoinsulemia, normoglycemia, prevented DCM, and improved lipid and antioxidant status. Mechanistically, ALA significantly upregulated the expression of cardiac H₂S-synthesizing enzymes and increased plasma H₂S concentration compared to DCM rats (p < 0.001).

CONCLUSION

ALA preserves myocardial integrity in T2DM likely by maintaining the expression of cardiac H₂S-synthezing enzymes and increasing plasma H₂S level.

Activation of renal CSE/H2S pathway by alpha-lipoic acid protects against histological and functional changes in the diabetic kidney

INTRODUCTION

We previously reported that alpha-lipoic acid (ALA) supplementation protects against progression of diabetic kidney disease (DKD). In this study, we aim to investigate whether the mechanism of renal protection by ALA involves renal cystathionine γ-lyase/hydrogen sulfide (CSE/H₂S) system in type 2 diabetes mellitus (T2DM).

METHODS

Thirty-seven male Sprague-Dawley rats underwent 12 h of overnight fasting. To induce T2DM, 30 of these rats received intraperitoneal administration of nicotinamide (110 mg/kg) and streptozotocin (55 mg/kg). T2DM rats then received either oral administration of ALA (60 mg/kg/day) or intraperitoneal administration of 40 mg/kg/day DL-propargylglycine (PAG, a CSE inhibitor) or both for 6 weeks after which rats were sacrificed and samples collected for analysis. Untreated diabetic and non-diabetic rats served as diabetic and healthy controls respectively.

RESULTS

T2DM was characterized by reduced pancreatic β-cell function and hyperglycemia. Histologically, untreated diabetic rats showed significantly damaged pancreatic islets, glomerular and tubular injury, with elevated levels of renal function markers compared to healthy control rats (p < 0.001). These pathological changes worsened significantly following PAG administration (p < 0.05). While some renal protection was observed in ALA+PAG rats, ALA administration in untreated diabetic rats provided superior protection comparable to healthy control rats, with improved antioxidant status, lipid profile and reduced inflammation. Mechanistically, ALA significantly activated renal CSE/H₂S system in diabetic rats, which was markedly suppressed in PAG-treated rats (p < 0.001).

CONCLUSION

Our data suggest that ALA protects against DKD development and progression by activating renal CSE/H₂S pathway. Hence, CSE/H₂S pathway may represent a therapeutic target in the treatment or prevention of DKD in diabetic patients.

Supplementation of conventional anti-diabetic therapy with alpha-lipoic acid prevents early development and progression of diabetic nephropathy

BACKGROUND

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease. Current pharmacological interventions only retard DN progression. Alpha-lipoic acid (ALA) is a potent antioxidant with beneficial effect in other diabetic complications. This study investigates whether ALA supplementation prevents early development and progression of DN.

METHOD

Fifty-eight male Sprague-Dawley rats were randomly assigned to healthy control and diabetic groups and subjected to overnight fasting. Type 2 diabetes mellitus (T2DM) was induced in diabetic group by intraperitoneal administration of nicotinamide (110 mg/kg) and streptozotocin (55 mg/kg). On day 3 after T2DM induction, diabetic rats received oral daily administration of ALA (60 mg/kg), gliclazide (15 mg/kg), ramipril (10 mg/kg) or drug combinations for 6 weeks. Untreated diabetic rats served as diabetic control. Blood, kidneys and pancreas were harvested for biochemical and histological analyses.

RESULT

Induction of T2DM resulted in hypoinsulinemia, hyperglycemia and renal pathology. ALA supplementation maintained β-cell function, normoinsulinemia and normoglycemia in diabetic rats, and prevented renal pathology (PAS, KIM-1, plasma creatinine, total protein, blood urea nitrogen, uric acid and urine albumin/creatinine ratio) and triglycerides level compared to diabetic control (p < 0.001). Additionally, ALA supplementation significantly prevented elevated serum and tissue malondialdehyde, collagen deposition, α-SMA expression, apoptosis and serum IL-1β and IL-6 levels while it markedly increased renal glutathione content and plasma HDL-C compared to diabetic control group (p < 0.001).

CONCLUSION

ALA supplementation prevents early development and progression of DN by exerting anti-hyperglycemic, antioxidant, anti-inflammatory, anti-fibrotic and anti-apoptotic effects. Our findings provide additional option for clinical treatment of DN in T2DM patients.

Combination Therapy of Alpha-Lipoic Acid, Gliclazide and Ramipril Protects Against Development of Diabetic Cardiomyopathy via Inhibition of TGF-β/Smad Pathway

Background: Diabetic cardiomyopathy (DCM) is a major long-term complication of diabetes mellitus, accounting for over 20% of annual mortality rate of diabetic patients globally. Although several existing anti-diabetic drugs have improved glycemic status in diabetic patients, prevalence of DCM is still high. This study investigates cardiac effect of alpha-lipoic acid (ALA) supplementation of anti-diabetic therapy in experimental DCM. Methods: Following 12 h of overnight fasting, 44 male Sprague Dawley rats were randomly assigned to two groups of healthy control (n = 7) and diabetic (n = 37) groups, and fasting blood glucose was measured. Type 2 diabetes mellitus (T2DM) was induced in diabetic group by intraperitoneal (i.p.) administration of nicotinamide (110 mg/kg) and streptozotocin (55 mg/kg). After confirmation of T2DM on day 3, diabetic rats received monotherapies with ALA (60 mg/kg; n = 7), gliclazide (15 mg/kg; n = 7), ramipril (10 mg/kg; n = 7) or combination of the three drugs (n = 7) for 6 weeks while untreated diabetic rats received distilled water and were used as diabetic control (n = 9). Rats were then sacrificed, and blood, pancreas and heart tissues were harvested for analyses using standard methods. Results: T2DM induction caused pancreatic islet destruction, hyperglycemia, weight loss, high relative heart weight, and development of DCM, which was characterized by myocardial degeneration and vacuolation, cardiac fibrosis, elevated cardiac damage markers (plasma and cardiac creatine kinase-myocardial band, brain natriuretic peptide and cardiac troponin I). Triple combination therapy of ALA, gliclazide and ramipril preserved islet structure, maintained body weight and blood glucose level, and prevented DCM development compared to diabetic control (p < 0.001). In addition, the combination therapy markedly reduced plasma levels of inflammatory markers (IL-1β, IL-6 and TNF-α), plasma and cardiac tissue malondialdehyde, triglycerides and total cholesterol while significantly increasing cardiac glutathione and superoxide dismutase activity and high-density lipoprotein-cholesterol compared to diabetic control (p < 0.001). Mechanistically, induction of T2DM upregulated cardiac expression of TGF-β1, phosphorylated Smad2 and Smad3 proteins, which were downregulated following triple combination therapy (p < 0.001). Conclusion: Triple combination therapy of ALA, gliclazide and ramipril prevented DCM development by inhibiting TGF-β1/Smad pathway. Our findings can be extrapolated to the human heart, which would provide effective additional pharmacological therapy against DCM in T2DM patients.

Prevention of Peripheral Distal Polyneuropathy in Patients with Diabetes: A Systematic Review

Background: Diabetic peripheral neuropathy (DPN) is the most frequent chronic complication and is that which generates the highest disability and mortality in diabetes mellitus (DM). As it is currently the only microvascular complication of DM without a specific treatment, prevention is essential. The aim of this study was to determine the most effective preventive strategy to avoid or delay the appearance and/or development of DPN in patients with DM. Methods: A systematic search was carried out in the main health science databases (PubMed, Scopus, CINAHL, PEDro and The Cochrane Library) from 1 January 2010 to 31 August 2020. The study selection was conducted by two independent reviewers and data extraction was performed by the author. The eligibility criteria included randomized clinical trials (RCTs) and cohort studies from RCTs. Results: Eleven studies were selected that included 23,595 participants with DM. The interventions evaluated were intensive or standard glycemic control, the use of drugs to achieve glycemic control, and the promotion of a healthy lifestyle and exercise. Intensive glucose control achieved a significant reduction in the development of DPN in TIDM patients, and lifestyle modifications and exercise achieved it moderately in TIIDM patients. Conclusions: The main preventive strategy for DPN is intensive glycemic control with a target HbA1c < 6% in patients with TIDM and standard control of 7.0−7.9 in patients with TIIDM, incorporating lifestyle modifications.

Alpha-Lipoic Acid Inhibits Spontaneous Diabetes and Autoimmune Recurrence in Non-Obese Diabetic Mice by Enhancing Differentiation of Regulatory T Cells and Showed Potential for Use in Cell Therapies for the Treatment of Type 1 Diabetes

Type 1 diabetes (T1D) is caused by the destruction of β cells in pancreatic islets by autoimmune T cells. Islet transplantation has been established as an effective treatment for T1D. However, the survival of islet grafts is often disrupted by recurrent autoimmunity. Alpha-lipoic acid (ALA) has been reported to have immunomodulatory effects and, therefore, may have therapeutic potential in the treatment of T1D. In this study, we investigated the therapeutic potential of ALA in autoimmunity inhibition. We treated non-obese diabetic (NOD) mice with spontaneous diabetes and islet-transplantation mice with ALA. The onset of diabetes was decreased and survival of the islet grafts was extended. The populations of Th1 cells decreased, and regulatory T cells (Tregs) increased in ALA-treated mice. The in vitro Treg differentiation was significantly increased by treatment with ALA. The adoptive transfer of ALA-differentiated Tregs into NOD recipients improved the outcome of the islet grafts. Our results showed that in vivo ALA treatment suppressed spontaneous diabetes and autoimmune recurrence in NOD mice by inhibiting the Th1 immune response and inducing the differentiation of Tregs. Our study also demonstrated the therapeutic potential of ALA in Treg-based cell therapies and islet transplantation used in the treatment of T1D.

Evaluation of the analgesic effect of ɑ-lipoic acid in treating pain disorders: A systematic review and meta-analysis of randomized controlled trials

Neuropathic pain is the most prevalent form of chronic pain caused by a disease of the nervous system, such as diabetic polyneuropathy. ɑ-Lipoic acid (ALA) is an antioxidant that has been widely studied for the treatment of pain symptoms in diverse conditions. Therefore, this study aimed to investigate the efficacy of ALA in the treatment of different types of pain through a systematic review and meta-analysis of randomized clinical trials. The study protocol was registered in the International Prospective Registry of Systematic Reviews (CRD42021261971). A search of the databases resulted in 1154 articles, 16 of which were included in the review (9 studies with diabetic polyneuropathy and 7 studies with other painful conditions). Most of the included studies had a low risk of bias. ALA showed efficacy for the treatment of headache, carpal tunnel syndrome and burning mouth syndrome. Meta-analysis was conducted only with the studies using diabetic polyneuropathy. Compared to placebo, ALA treatment decreased the total symptom score (TSS). The subgroup meta-analysis indicated a decrease of stabbing pain, burning, paraesthesia, and numbness in ALA-treated patients compared to placebo. In addition, both routes of administration, intravenous and oral, demonstrated the efficacy to reduce TSS. Therefore, ALA should be used to treat diabetic polyneuropathy pain symptoms. However, the standardization of treatment time and the dose may advance for the approval of ALA for clinical use in diabetic polyneuroneuropathy.

Mechanics Insights of Alpha-Lipoic Acid against Cardiovascular Diseases during COVID-19 Infection

Coronavirus disease 2019 (COVID-19) was first reported in Wuhan, China, in late December 2019. Since then, COVID-19 has spread rapidly worldwide and was declared a global pandemic on 20 March 2020. Cardiovascular complications are rapidly emerging as a major peril in COVID-19 in addition to respiratory disease. The mechanisms underlying the excessive effect of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection on patients with cardiovascular comorbidities remain only partly understood. SARS-CoV-2 infection is caused by binding of the viral surface spike (S) protein to the human angiotensin-converting enzyme 2 (ACE2), followed by the activation of the S protein by transmembrane protease serine 2 (TMPRSS2). ACE2 is expressed in the lung (mainly in type II alveolar cells), heart, blood vessels, small intestine, etc., and appears to be the predominant portal to the cellular entry of the virus. Based on current information, most people infected with SARS-CoV-2 virus have a good prognosis, while a few patients reach critical condition, especially the elderly and those with chronic underlying diseases. The "cytokine storm" observed in patients with severe COVID-19 contributes to the destruction of the endothelium, leading to "acute respiratory distress syndrome" (ARDS), multiorgan failure, and death. At the origin of the general proinflammatory state may be the SARS-CoV-2-mediated redox status in endothelial cells via the upregulation of ACE/Ang II/AT1 receptors pathway or the increased mitochondrial reactive oxygen species (mtROS) production. Furthermore, this vicious circle between oxidative stress (OS) and inflammation induces endothelial dysfunction, endothelial senescence, high risk of thrombosis and coagulopathy. The microvascular dysfunction and the formation of microthrombi in a way differentiate the SARS-CoV-2 infection from the other respiratory diseases and bring it closer to cardiovascular diseases like myocardial infarction and stroke. Due the role played by OS in the evolution of viral infection and in the development of COVID-19 complications, the use of antioxidants as adjuvant therapy seems appropriate in this new pathology. Alpha-lipoic acid (ALA) could be a promising candidate that, through its wide tissue distribution and versatile antioxidant properties, interferes with several signaling pathways. Thus, ALA improves endothelial function by restoring the endothelial nitric oxide synthase activity and presents an anti-inflammatory effect dependent or independent of its antioxidant properties. By improving mitochondrial function, it can sustain the tissues' homeostasis in critical situation and by enhancing the reduced glutathione it could indirectly strengthen the immune system. This complex analysis could open a new therapeutic perspective for ALA in COVID-19 infection.

Double-blind, randomized, placebo-controlled crossover trial of alpha-lipoic acid for the treatment of fibromyalgia pain: the IMPALA trial

ABSTRACT

Fibromyalgia is a common and challenging chronic pain disorder with few, if any, highly effective and well-tolerated treatments. Alpha-lipoic acid (ALA) is a nonsedating antioxidant with evidence of efficacy in the treatment of symptomatic diabetic neuropathy that has not been evaluated in the setting of fibromyalgia treatment. Thus, we conducted a single-centre, proof-of-concept, randomized, placebo-controlled, crossover trial of ALA for the treatment of fibromyalgia. Twenty-seven participants were recruited, and 24 participants completed both treatment periods of the trial. The median maximal tolerated dose of ALA in this trial was 1663 mg/day. Treatment-emergent adverse events with ALA were infrequent and not statistically different from placebo. For the primary outcome of pain intensity, and for several other validated secondary outcomes, there were no statistically significant differences between placebo and ALA. A post hoc exploratory subgroup analysis showed a significant interaction between gender and treatment with a significant favourable placebo-ALA difference in pain for men, but not for women. Overall, the results of this trial do not provide any evidence to suggest promise for ALA as an effective treatment for fibromyalgia, which is predominantly prevalent in women. This negative clinical trial represents an important step in a collective strategy to identify new, better tolerated and more effective treatments for fibromyalgia.

The Role of Alpha-lipoic Acid Supplementation in the Prevention of Diabetes Complications: A Comprehensive Review of Clinical Trials

Alpha-lipoic acid (ALA) is a substantial antioxidant in the prevention of diabetes and diabetes complications. It can regenerate other antioxidants like vitamin E, vitamin C, Coenzyme Q10 and glutathione and is often known as a universal antioxidant. Antioxidants play a role in diabetes treatment due to hyperglycemia-induced stimulation of the polyol pathway and formation of advanced glycation end products (AGE) and reactive oxygen species (ROS). Clinical trials examining alpha-lipoic acid supplementation on diabetic neuropathy, nephropathy, cardiomyopathy and erectile dysfunction display positive results, particularly in pain amelioration in neuropathy, asymmetric dimethylarginine reductions in nephropathy and improved oscillatory potential and contrast sensitivity in retinopathy. In diabetic cardiomyopathy (DCM), ALA offers protection through inhibition of NF-kB activation, reduction of fas-ligand and decrease in matrix metalloproteinase-2. This comprehensive review summarises and provides an understanding of the importance of alpha- lipoic acid supplementation to prevent diabetes complications.

Alpha-lipoic acid: A possible pharmacological agent for treating dry eye disease and retinopathy in diabetes

Alpha-lipoic acid (ALA) is a naturally occurring dithiol micronutrient which acts as a cofactor for mitochondrial enzyme activity. Due to its potential antioxidant activity, it is considered as "universal antioxidant". Previous studies reported the pharmacological benefits of ALA such as glycaemic control, improved insulin sensitivity and alleviation of diabetic complications such as neuropathy and cardiovascular diseases. Dry eye disease and retinopathy are prevalent in diabetic patients. Experimental studies demonstrated the beneficial effects of ALA in dry eye and diabetic retinopathy. ALA can prevent the dry eye by down regulating the expression of matrix metalloproteinase-9 in the corneal epithelial cells and activating the antioxidant status of the ocular surface. Furthermore, its direct antioxidant effect can also prevent oxidative stress-induced corneal surface erosion and lachrymal gland damage. ALA prevents diabetic retinopathy through inhibition of O-linked β-N-acetylglucosamine transferase and nuclear factor-kappa B activity and alleviation of oxidative stress. It can activate the nuclear factor erythroid-2-related factor 2 and AMP-activated protein kinase in retinal ganglion cells. Clinical trials conducted in pre-retinopathic diabetic patients showed ALA with genistein and vitamins could protect the retinal cells and decline the inflammatory effect in diabetic patients. However, studies are scant to explore its beneficial effects in dry eye disease and diabetic retinopathy. Therefore, this review article discusses an update on the role of ALA in dry eye disease and diabetic retinopathy, two ocular diseases prevalent in diabetic patients.

Efficacy and Safety of the Combination of Superoxide Dismutase, Alpha Lipoic Acid, Vitamin B12, and Carnitine for 12 Months in Patients with Diabetic Neuropathy

Aim: To investigate the efficacy of Superoxide Dismutase, Alpha Lipoic Acid, Acetyl L-Carnitine, and Vitamin B12 (B12) in one tablet in Diabetic Neuropathy (DN). Patients–methods: In this prospective, double-blind, placebo-controlled study, 85 patients with Diabetes Mellitus Type 2 (DMT2) were randomly assigned, either to receive the combination of four elements (active group, n = 43), or placebo (n = 42) for 12 months. We used the Michigan Neuropathy Screening Instrument Questionnaire and Examination (MNSIQ and MNSIE), measured the vibration perception threshold (BIO), and Cardiovascular Autonomic Reflex Tests (CARTs). Nerve function was assessed by DPN Check [sural nerve conduction velocity (SNCV) and amplitude (SNAP)]. Pain (PS) and quality of life (QL) questionnaires were administered. Results: At follow-up, BIO, MNSIQ, QL, PAIN, and SNCV, SNAP, and B12 levels had significantly improved inactive group (p < 0.001, p < 0.001, p < 0.001, p < 0.001, p = 0.027, p = 0.031, and p < 0.001 respectively), whereas the inplacebo group MCR (mean circular resultant) and PAIN deteriorated (p < 0.001, p < 0.001). The changes in MNSIQ, QL, SNCV, BIO, and PAIN differed significantly between groups (p < 0.001, p < 0.001, p = 0.031, p < 0.001, and p < 0.001 respectively). Conclusions: The combination of the four elements in one tablet for 12 months in patients with DMT2 improved all indices of peripheral neuropathy, including SNAP and SNCV, pain, and Quality of Life perception, except CARTs and MNSIE.

An updated systematic review and dose-response meta-analysis of the effects of α-lipoic acid supplementation on glycemic markers in adults

This systematic review and dose-response meta-analysis was conducted to summarize data from available clinical trials on the effects of α-lipoic acid (ALA) supplementation on glycemic markers including glucose, hemoglobin A_1c (HbA_1c), insulin, homeostatic model assessment of insulin resistance (HOMA-IR), HOMA-β, and quantitative insulin check index in adults. A comprehensive literature search was conducted in the electronic databases of PubMed, Web of Science, ProQuest, Embase and SCOPUS from inception to February 2020. Among all of the eligible studies, 28 articles were selected. The weighted mean differences (WMD) and 95% confidence intervals (CI) were calculated to evaluate the pooled effect size. Between-study heterogeneity was evaluated using Cochran's Q test and I². Subgroup analysis was done to evaluate the potential sources of heterogeneity. The dose-response relationship was evaluated using fractional polynomial modeling. Twenty eight eligible studies with a total sample size of 1,016 participants were included in the current meta-analysis. The findings of the meta-analysis showed that ALA supplementation significantly reduced insulin (WMD: -0.64; CI: -1.287 to 0.004, P = .04), HOMA-IR (WMD: -0.48; 95% CI: -0.79 to -0.16; P = .002). No change in glucose or HbA1C was reported. Moreover, the effect of ALA on insulin was duration-dependent (P_{non-linearity} = 0.04). No evidence of departure from linearity was observed between dose and duration of the ALA supplementation on other markers. The subgrouping revealed that ALA dosage and duration of ALA supplementation, health status of participants, geographic locations and the studies' quality are possible sources of heterogeneity. In summary, ALA supplementation improves serum insulin and insulin resistance in a two-class and duration dependent non-linear analysis.

Is there cardiac autonomic neuropathy in prediabetes?

Although there is considerably more data showing an association between type 2 diabetes mellitus (T2DM) and autonomic neuropathy, accumulating evidence indicates that cardiovascular autonomic neuropathy (CAN) is common in persons with impaired glucose tolerance (IGT). Furthermore, CAN may occur early after a metabolic insult and obesity, especially among mean, and seems to play an important role in the early pathogenesis of CAN. Autonomic symptoms are common in subjects with IGT. In addition to defects in CAN, in subjects with IGT, there is impaired sudomotor function and abnormalities of endothelial peripheral vasoreactivity. At the present time, the only interventions that may be effective in preventing or reversing IGT associated autonomic neuropathy are lifestyle improvement. These include a tailored diet and exercise program. Other approaches that may be beneficial include modulation of oxidative stress and improvement of metabolic regulation in subjects with IGT. Interventions are most likely to be effective early in the course of disease and therefore it is extremely important to have early diagnosis of IGT and autonomic neuropathy.

Management of Neuropathic Pain in Polyneuropathy

PURPOSE OF REVIEW

Many polyneuropathies cause significant neuropathic pain, resulting in substantial morbidity and reduced quality of life. Appropriate management is crucial for maintaining quality of life for patients with painful polyneuropathies. The US Food and Drug Administration (FDA) has only approved one new drug for painful diabetic neuropathy in the past decade, a topical capsaicin patch that was initially approved for the treatment of postherpetic neuralgia in 2009. Gabapentinoids and serotonin norepinephrine reuptake inhibitors (SNRIs) continue to have an advantage in safety profiles and efficacy. Other antiepileptic medications remain second-line agents because of fewer studies documenting efficacy.

RECENT FINDINGS

This article reviews recent literature on complementary and pharmacologic therapies for the management of painful polyneuropathies. Exercise has emerged as an important therapeutic tool and may also improve the underlying polyneuropathy in the setting of obesity, metabolic syndrome, and diabetes.

SUMMARY

The approach to management of painful polyneuropathies is multifactorial, using both pharmacologic and nonpharmacologic measures to improve pain severity and patient quality of life.

Treatment of Diabetic Cardiovascular Autonomic, Peripheral and Painful Neuropathy. Focus on the Treatment of Cardiovascular Autonomic Neuropathy with ACE Inhibitors

Neuropathies of the peripheral and autonomic nervous systems affect up to half of all people with diabetes mellitus, and are major risk factors for foot ulceration, amputation and cardiovascular dysfunction. Peripheral neuropathies manifest with either painful or painless symptoms, but many patients experience both. Once diagnosed appropriately, painful diabetic neuropathy management presents a unique challenge for physicians and should be considered as a syndrome, clinically distinct from diabetic peripheral neuropathy. The aetiology is multifactorial: metabolic changes in diabetes may directly affect neural tissue and neurodegenerative changes are precipitated by compromised nerve vascular supply. Metabolic changes include the elevated polyol pathway activity, the increased oxidative stress, the formation of advanced glycation and lipoxidation end products, and various pro-inflammatory changes. These mechanisms work in combination and interact in a mutually facilitatory fashion. This review focuses on the current therapies for the management of peripheral and cardiovascular autonomic neuropathy and of painful neuropathy as a distinct entity, based on the current knowledge of diabetic neuropathy. Moreover, the role of ACE inhibition has been explored in the treatment of Cardiovascular Autonomic Neuropathy.

Assessment of the efficacy of α-lipoic acid in treatment of diabetes mellitus patients with erectile dysfunction: A protocol for systematic review and meta-analysis

BACKGROUND

Diabetes mellitus with erectile dysfunction (DMED) is one of the most common causes of disability in diabetic population, and its pathogenesis is related to a variety of factors. Because its pathogenesis is complex and the existing treatment methods have limitations, DMED is difficult to treat in clinical. Recently, some studies have shown that α-lipoic acid (ALA) is associated with DMED, but there is no systematic review and meta-analysis on the relationship between ALA and DMED.

METHODS

We will search each database from the built-in until July 2020. The English literature mainly searches Cochrane Library, PubMed, EMBASE, and Web of Science, while the Chinese literature comes from CNKI, CBM, VIP, and Wangfang database. Simultaneously we will retrieve clinical registration tests and grey literatures. This study only screen the clinical randomized controlled trials (RCTs) about ALA for DMED to assess its efficacy. The 2 researchers worked independently on literature selection, data extraction, and quality assessment. The dichotomous data is represented by relative risk (RR), and the continuous is expressed by mean difference (MD) or standard mean difference (SMD), eventually the data is synthesized using a fixed effect model (FEM) or a random effect model (REM) depending on whether or not heterogeneity exists. Erectile dysfunction (ED) will be diagnosed by the International Index of Erectile Function 5 (IIEF-5) score. Finally, meta-analysis was conducted by RevMan software version 5.3.

RESULTS

This study will synthesize and provide high quality to evaluate the effectiveness of ALA supplementation for the treatment of DMED.

CONCLUSION

This systematic review aims to provide new options for ALA supplementation treatment of DMED in terms of its efficacy and safety.

PROSPERO REGISTRATION NUMBER

INPLASY202070130.

Classical Therapies Versus Combined Therapies in Diabetic Neuropathy

The aim of our study was to evaluate the classical therapies represented by adequate glycemic control and lifestyle changes versus classical therapies combined with new antioxidant therapies in patients with diabetic neuropathy. We conducted an observational, prospective study, between October 2017 and December 2019, which included a number of 188 patients suffering from diabetic neuropathy. In order to evaluate the response to the therapeutic protocol, we used the MNSI (Michigan neuropathy screening instrument). Responder group was defined as a decrease in MNSI (<7) from baseline to one year. According to this 34.04% (n=64) of patients were responders to classical therapy while a higher number of patients responded to combined therapy (n=73, representing 38.83%). In the group of responders, the subgroups that predicted the prevention of MNSI increase (decrease in the impact of diabetic neuropathy) in the group treated with combined therapy compared to classical therapy, related to clinicopathological features, after one year included: gender female (p=0.0415), body mass index <30kg/m2 (p=0.0335), absence of cardiovascular disease (p=0.0006) and absence of dyslipidemia (p=0.0288). In conclusion, we demonstrated an increased response to combined therapy after one year of treatment. Thus, combined therapy is an alternative for reducing side effects and for increasing efficiency.

Diabetic Peripheral Neuropathy Is Associated With Higher Systolic Blood Pressure in Adults With Type 2 Diabetes With and Without Hypertension in the Chinese Han Population

OBJECTIVES

Our aim in this study was to investigate the association between diabetic peripheral neuropathy (DPN) and above-normal blood pressure in nonhypertensive adult patients with type 2 diabetes mellitus (T2DM). We also compared achievement of clinical targets for DPN and non-DPN with T2DM.

METHODS

A retrospective survey was administered to 3,810 patients with T2DM. Cases were grouped according to the Toronto Clinical Scoring System as follows: non-DPN, mild DPN, moderate DPN and severe DPN. A total of 1,835 patients (hypertensive, 1,247; nonhypertensive, 588) also underwent nerve conduction velocity testing, and then was divided into quartile groups.

RESULTS

Irrespective of hypertension, systolic blood pressure (SBP) and glycated hemoglobin levels in the DPN group were higher than those in the non-DPN group (p<0.001). In hypertensive patients, blood pressure goal achievement was lower in the DPN group compared with the non-DPN group (31.1% vs 40.5%, p<0.05). Compared with the nerve conduction velocity Q1 (<P25%) group, optimal SBP of the Q2 (P25% to P50%), Q3 (P50% to P75%) and Q4 (>P75%) groups decreased by 62.2%, 68.2% and 78.0%, respectively. In the nonhypertensive patients, detection of optimal SBP was lower in the DPN group than in the non-DPN group (p<0.05). After adjusting for age, sex and diabetes duration (model 2), a 3-point higher DPN score on the Toronto Clinical Scoring System was associated with an SBP level of 4.2 mmHg higher (95% confidence interval, 0.01 to 0.17; p<0.01) in nonhypertensive patients with diabetes.

CONCLUSIONS

DPN is associated with difficulty in hypertension management in T2DM. It is also associated with elevated systolic blood hypertension, even in nonhypertensive patients with diabetes. Elevated SBP in nonhypertensive T2DM may be also worthy of further attention.

Insights on the Use of α-Lipoic Acid for Therapeutic Purposes

α-lipoic acid (ALA, thioctic acid) is an organosulfur component produced from plants, animals, and humans. It has various properties, among them great antioxidant potential and is widely used as a racemic drug for diabetic polyneuropathy-associated pain and paresthesia. Naturally, ALA is located in mitochondria, where it is used as a cofactor for pyruvate dehydrogenase (PDH) and α-ketoglutarate dehydrogenase complexes. Despite its various potentials, ALA therapeutic efficacy is relatively low due to its pharmacokinetic profile. Data suggests that ALA has a short half-life and bioavailability (about 30%) triggered by its hepatic degradation, reduced solubility as well as instability in the stomach. However, the use of various innovative formulations has greatly improved ALA bioavailability. The R enantiomer of ALA shows better pharmacokinetic parameters, including increased bioavailability as compared to its S enantiomer. Indeed, the use of amphiphilic matrices has capability to improve ALA bioavailability and intestinal absorption. Also, ALA's liquid formulations are associated with greater plasma concentration and bioavailability as compared to its solidified dosage form. Thus, improved formulations can increase both ALA absorption and bioavailability, leading to a raise in therapeutic efficacy. Interestingly, ALA bioavailability will be dependent on age, while no difference has been found for gender. The present review aims to provide an updated on studies from preclinical to clinical trials assessing ALA's usages in diabetic patients with neuropathy, obesity, central nervous system-related diseases and abnormalities in pregnancy.

Development of measures of polyneuropathy impairment in hATTR amyloidosis: From NIS to mNIS + 7

Hereditary transthyretin-mediated amyloidosis (hATTR amyloidosis) is a rare, life-threatening disease, caused by point mutations in the transthyretin gene. It is a heterogeneous, multisystem disease with rapidly progressing polyneuropathy (including sensory, motor, and autonomic impairments) and cardiac dysfunction. Measures used to assess polyneuropathy in other diseases have been tested as endpoints in hATTR amyloidosis clinical trials (i.e. Neuropathy Impairment Score [NIS], NIS-lower limb, and NIS + 7), yet the unique nature of the polyneuropathy in this disease has necessitated modifications to these scales. In particular, the heterogeneous impairment and the aggressive disease course have been key drivers in developing scales that better capture the disease burden and progression of polyneuropathy in hATTR amyloidosis. The modified NIS + 7 (mNIS + 7) scale was specifically designed to assess polyneuropathy impairment in patients with hATTR amyloidosis, and has been the primary endpoint in two recent, phase III studies in this disease. The mNIS + 7 uses highly standardized, quantitative, and referenced assessments to quantify decreased muscle weakness, muscle stretch reflexes, sensory loss, and autonomic impairment. Physicians using this scale in clinical trials should be specifically trained and monitored to minimize variability. This article discusses the different scales that have been/are being used to assess polyneuropathy in patients with hATTR amyloidosis, their correlation with other disease assessments, and reflects on how and why scales have evolved to the latest iteration of mNIS + 7.

Physical activity and dietary interventions in diabetic neuropathy: a systematic review

PURPOSE

Diabetic neuropathy is a common and disabling disorder, and there are currently no proven effective disease-modifying treatments. Physical activity and dietary interventions in patients with diabetes and diabetic neuropathy have multiple beneficial effects and are generally low risk, which makes lifestyle interventions an attractive treatment option. We reviewed the literature on the effects of physical activity and dietary interventions on length-dependent peripheral neuropathy and cardiac autonomic neuropathy in diabetes.

METHODS

The electronic database PubMed was systematically searched for original human and mouse model studies examining the effect of either dietary or physical activity interventions in subjects with diabetes, prediabetes, or metabolic syndrome.

RESULTS

Twenty studies are included in this review. Fourteen studies were human studies and six were in mice. Studies were generally small with few controlled trials, and there are no widely agreed upon outcome measures.

CONCLUSIONS

Recent research indicates that dietary interventions are effective in modifying diabetic neuropathy in animal models, and there are promising data that they may also ameliorate diabetic neuropathy in humans. It has been known for some time that lifestyle interventions can prevent the development of diabetic neuropathy in type 2 diabetes mellitus subjects. However, there is emerging evidence that lifestyle interventions are effective in individuals with established diabetic neuropathy. In addition to the observed clinical value of lifestyle interventions, there is emerging evidence of effects on biochemical pathways that improve muscle function and affect other organ systems, including the peripheral nerve. However, data from randomized controlled trials are needed.

Hypertension Contributes to Neuropathy in Patients With Type 1 Diabetes

BACKGROUND

Diabetic peripheral neuropathy (DPN) can lead to foot ulceration and amputation. There are currently no disease-modifying therapies for DPN. The aim of this study was to determine if hypertension contributes to DPN in patients with type 1 diabetes mellitus (T1DM).

METHODS

Subjects with T1DM (n = 70) and controls (n = 78) underwent a comprehensive assessment of DPN.

RESULTS

Hypertension was present in 40 of 70 T1DM subjects and 20 of 78 controls. Hypertension was associated with abnormal nerve conduction parameters (P = 0.03 to <0.001), increased vibration perception threshold (P = 0.01) and reduced corneal nerve fiber density and length (P = 0.02) in subjects with T1DM. However, after adjusting for confounding factors only tibial compound motor action potential and nerve conduction velocity were associated with hypertension (P = 0.03) and systolic blood pressure (P < 0.01 to <0.0001). Hypertension had no effect on neuropathy in subjects without diabetes.

CONCLUSIONS

This study shows that hypertension is associated with impaired nerve conduction in T1DM. It supports previous small trials showing that angiotensin-converting enzyme inhibitors improve nerve conduction and advocates the need for larger clinical trials with blood pressure lowering agents in DPN.

The Effect of 600 mg Alpha-lipoic Acid Supplementation on Oxidative Stress, Inflammation, and RAGE in Older Adults with Type 2 Diabetes Mellitus

Alpha-lipoic acid (ALA) has been used as a dietary supplement at different doses in patients with diabetes mellitus type 2 (T2DM) due to its antioxidant, anti-inflammatory, and hypoglycemic effects. However, the reports on the effects of ALA are controversial. For this reason, the purpose of the present study was to determine the effect of 600 mg/day of ALA on the markers of oxidative stress (OxS) and inflammation and RAGE in older adults with T2DM. A quasiexperimental study was carried out with a sample of 135 sedentary subjects (98 women and 37 men) with a mean age of 64 ± 1 years, who all had T2DM. The sample was divided into three groups: (i) experimental group (EG) with 50 subjects, (ii) placebo group (PG) with 50 subjects, and control group (CG) with 35 subjects. We obtained the following measurements in all subjects (pre- and posttreatment): glycosylated hemoglobin (HbA1c), receptor for advanced glycation end products (RAGE), 8-isoprostane, superoxide dismutase (SOD), glutathione peroxidase (GPx), total antioxidant status (TAS), and inflammatory (CRP, TNF-α, IL-6, IL-8, and IL-10) markers. Regarding the effect of ALA on HbA1c, a decrease was observed in the EG (baseline 8.9 ± 0.2 vs. posttreatment 8.6 ± 0.3) and the PG (baseline 8.8 ± 0.2 vs. posttreatment 8.4 ± 0.3) compared to the CG (baseline 8.8 ± 0.3 vs. six months 9.1 ± 0.3) although the difference was not statistically significant (p < 0.05). There was a statistically significant decrease (p < 0.05) in the blood concentration of 8-isoprostane in the EG and PG with respect to the CG (EG: baseline 100 ± 3 vs. posttreatment 57 ± 3, PG: baseline 106 ± 7 vs. posttreatment 77 ± 5, and CG: baseline 94 ± 10 vs. six months 107 ± 11 pg/mL). Likewise, a statistically significant decrease (p < 0.05) in the concentration of the RAGE was found in the EG (baseline 1636 ± 88 vs. posttreatment 1144 ± 68) and the PG (baseline 1506 ± 97 vs. posttreatment 1016 ± 82) compared to CG (baseline 1407 ± 112 vs. six months 1506 ± 128). A statistically significant decrease was also observed in all markers of inflammation and in the activity of SOD and GPx in the CG with respect to the EG and PG. Our findings suggest that the administration of ALA at a dose of 600 mg/day for six months has a similar effect to that of placebo on oxidative stress, inflammation, and RAGE in older adults with T2DM. Therefore, higher doses of ALA should be tried to have this effect. This trial is registered with trial registration number ISRCTN13159380.

Update on the Impact, Diagnosis and Management of Cardiovascular Autonomic Neuropathy in Diabetes: What Is Defined, What Is New, and What Is Unmet

The burden of diabetic cardiovascular autonomic neuropathy (CAN) is expected to increase due to the diabetes epidemic and its early and widespread appearance. CAN has a definite prognostic role for mortality and cardiovascular morbidity. Putative mechanisms for this are tachycardia, QT interval prolongation, orthostatic hypotension, reverse dipping, and impaired heart rate variability, while emerging mechanisms like inflammation support the pervasiveness of autonomic dysfunction. Efforts to overcome CAN under-diagnosis are on the table: by promoting screening for symptoms and signs; by simplifying cardiovascular reflex tests; and by selecting the candidates for screening. CAN assessment allows for treatment of its manifestations, cardiovascular risk stratification, and tailoring therapeutic targets. Risk factors for CAN are mainly glycaemic control in type 1 diabetes mellitus (T1DM) and, in addition, hypertension, dyslipidaemia, and obesity in type 2 diabetes mellitus (T2DM), while preliminary data regard glycaemic variability, vitamin B12 and D changes, oxidative stress, inflammation, and genetic biomarkers. Glycaemic control prevents CAN in T1DM, whereas multifactorial intervention might be effective in T2DM. Lifestyle intervention improves autonomic function mostly in pre-diabetes. While there is no conclusive evidence for a disease-modifying therapy, treatment of CAN manifestations is available. The modulation of autonomic function by SGLT2i represents a promising research field with possible clinical relevance.

Emerging Biomarkers, Tools, and Treatments for Diabetic Polyneuropathy

Diabetic neuropathy, with its major clinical sequels, notably neuropathic pain, foot ulcers, and autonomic dysfunction, is associated with substantial morbidity, increased risk of mortality, and reduced quality of life. Despite its major clinical impact, diabetic neuropathy remains underdiagnosed and undertreated. Moreover, the evidence supporting a benefit for causal treatment is weak at least in patients with type 2 diabetes, and current pharmacotherapy is largely limited to symptomatic treatment options. Thus, a better understanding of the underlying pathophysiology is mandatory for translation into new diagnostic and treatment approaches. Improved knowledge about pathogenic pathways implicated in the development of diabetic neuropathy could lead to novel diagnostic techniques that have the potential of improving the early detection of neuropathy in diabetes and prediabetes to eventually embark on new treatment strategies. In this review, we first provide an overview on the current clinical aspects and illustrate the pathogenetic concepts of (pre)diabetic neuropathy. We then describe the biomarkers emerging from these concepts and novel diagnostic tools and appraise their utility in the early detection and prediction of predominantly distal sensorimotor polyneuropathy. Finally, we discuss the evidence for and limitations of the current and novel therapy options with particular emphasis on lifestyle modification and pathogenesis-derived treatment approaches. Altogether, recent years have brought forth a multitude of emerging biomarkers reflecting different pathogenic pathways such as oxidative stress and inflammation and diagnostic tools for an early detection and prediction of (pre)diabetic neuropathy. Ultimately, these insights should culminate in improving our therapeutic armamentarium against this common and debilitating or even life-threatening condition.

Ranirestat Improved Nerve Conduction Velocities, Sensory Perception, and Intraepidermal Nerve Fiber Density in Rats with Overt Diabetic Polyneuropathy

Distal sensory-motor polyneuropathy is one of the most frequent diabetic complications. However, few therapies address the etiology of neurodegeneration in the peripheral nervous systems of diabetic patients. Several metabolic mechanisms have been proposed as etiologies of this polyneuropathy. In this study, we revisited one of those mechanisms, the polyol pathway, and investigated the curative effects of a novel strong aldose reductase inhibitor, ranirestat, in streptozotocin-induced diabetic rats with preexisting polyneuropathy. Twelve weeks after the onset of diabetes, rats which had an established polyneuropathy were treated once daily with a placebo, ranirestat, or epalrestat, over 6 weeks. Before and after the treatment, nerve conduction velocities and thermal perception threshold of hindlimbs were examined. After the treatment, intraepidermal fiber density was evaluated. As an ex vivo assay, murine dorsal root ganglion cells were dispersed and cultured with or without 1 μmol/l ranirestat for 48 hours. After the culture, neurite outgrowth was quantified using immunological staining. Sensory nerve conduction velocity increased in diabetic rats treated with ranirestat (43.3 ± 3.6 m/s) compared with rats treated with placebo (39.8 ± 2.3). Motor nerve conduction velocity also increased in the ranirestat group (45.6 ± 3.9) compared with the placebo group (38.9 ± 3.5). The foot withdrawal latency to noxious heating was improved in the ranirestat group (17.7 ± 0.6 seconds) compared with the placebo group (20.6 ± 0.6). The decrease in the intraepidermal fiber density was significant in the diabetic placebo group (21.6 ± 1.7/mm) but not significant in the diabetic ranirestat group (26.2 ± 1.2) compared with the nondiabetic placebo group (30.3 ± 1.5). Neurite outgrowth was promoted in the neurons supplemented with ranirestat (control 1446 ± 147 μm/neuron, ranirestat 2175 ± 149). Ranirestat improved the peripheral nervous dysfunctions in rats with advanced diabetic polyneuropathy. Ranirestat could have potential for regeneration in the peripheral nervous system of diabetic rats.

Epigenetic Treatment of Neurodegenerative Ophthalmic Disorders: An Eye Toward the Future

Eye disease is one of the primary medical conditions that requires attention and therapeutic intervention in ageing populations worldwide. Further, the global burden of diabetes and obesity, along with heart disease, all lead to secondary manifestations of ophthalmic distress. Therefore, there is increased interest in developing innovative new approaches that target various mechanisms and sequelae driving conditions that result in adverse vision. The research challenge is even greater given that the terrain of eye diseases is difficult to landscape into a single therapeutic theme. This report addresses the burden of eye disease due to mitochondrial dysfunction, including antioxidant, autophagic, epigenetic, mitophagic, and other cellular processes that modulate the biomedical end result. In this light, we single out lipoic acid as a potent known natural activator of these pathways, along with alternative and potentially more effective conjugates, which together harness the necessary potency, specificity, and biodistribution parameters required for improved therapeutic outcomes.

The Quest for more Research on Painful Diabetic Neuropathy

A 62-year-old diabetologist diagnosed himself to have diabetes type-2, with an HbA1c of 9.5. Five months after lifestyle intervention and a multi-drug approach, HbA1c was 6.3, systolic blood pressure was below 135mmHg and BMI reduced to 27. But he suffered from severe painful diabetic neuropathy. Therefore he decided to visit his friend, a famous neuroscientist at an even more famous university. He asked him several plain questions: 1. What is the natural course of painful diabetic neuropathy? 2. Why do I have, despite almost normalizing HbA1c, more problems than before? 3. Are you sure my problems are due to diabetes or should we do a nerve biopsy? 4. Are there imaging techniques helpful for the diagnosis of this diabetic complication, starting in the distal nerve endings of the foot and slowly moving ahead? 5. Can you suggest any drug, specific and effective, for relieving painful diabetic neuropathy? This review will use the experts' answers to the questions of the diabetologist, not only to give a summary of the current knowledge, but even more to highlight areas of research needed for improving the fate of patients with painful diabetic neuropathy. Based on the unknowns, which exceed the knowns in diabetic neuropathy, a quest for more public support of research is made.

Predictors of response to treatment with actovegin for 6 months in patients with type 2 diabetes and symptomatic polyneuropathy

AIMS

To evaluate two definitions of response and the predictive value of baseline covariates for response to actovegin treatment in type 2 diabetic patients with symptomatic diabetic sensorimotor polyneuropathy (DSPN).

METHODS

Response to 6-months treatment with actovegin or placebo was defined as a clinically meaningful decline from baseline to 6months in (1) both Neuropathy Impairment Score of Lower Limbs (NIS-LL) ≥2 points and Total Symptom Score (TSS) >50% and (2) NIS-LL ≥2 points only. Nineteen baseline covariates were evaluated using separate logistic regression models and either both NIS-LL and TSS or NIS-LL response definitions.

RESULTS

Intention-to-treat analysis included 567 patients. Actovegin treatment compared to placebo was associated with better odds of response (OR [95% CI] of 1.73 [1.21-2.48] for definition 1 and 1.94 [1.33-2.84] for definition 2). Significant interaction with actovegin treatment was noted only for baseline use of angiotensin receptor blockers (ARBs)/angiotensinogen converting enzyme inhibitors (ACEIs), resulting in a reduced treatment response (P=0.03).

CONCLUSIONS

Actovegin treatment was associated with a clinically meaningful response in neuropathic symptoms and/or impairments in patients with symptomatic DSPN. Since only one predictor of response to actovegin treatment was identified, this drug seems an appropriate therapy for the majority of patients with DSPN.

Neurological outcomes of antidiabetic therapy: What the neurologist should know

Considering the causative or contributory effects of diabetes mellitus on common neurological diseases such as polyneuropathy, stroke and dementia, modern antidiabetic drugs may be expected to reduce incidence or progression of these conditions. Nevertheless, most observed benefits have been small, except in the context of therapy for diabetes mellitus type I and new-onset polyneuropathy. Recently, semaglutide, a GLP-1 analog, has been shown to significantly reduce stroke incidence in a randomized controlled trial. Beneficial effects of antidiabetic drugs on stroke severity or outcome have been controversial, though. The level of risk conferred by diabetes mellitus, the complex pathophysiology of neurological diseases, issues of trial design, side-effects of antidiabetic drugs as well as co-medication might be interacting factors that determine the performance of antidiabetic therapy with respect to neurological outcomes. It might be speculated that early treatment of prediabetes might prevent cerebral arteriosclerosis, cognitive decline or polyneuropathy more effectively, but this remains to be demonstrated.

Prevalence and Treatment of Neuropathic Pain in Kidney and Liver Transplant Recipients

OBJECTIVES

Neurologic complications are common after kidney and liver transplant. Neurologic complications affect mortality and morbidity in transplant recipients, and neuropathic pain is an important symptom affecting a patient's quality of life. The aim of the present study was to provide readers with our experience regarding causes and treatment of neuropathic pain in patients undergoing kidney and liver transplant at our transplantation center.

MATERIALS AND METHODS

The medical data of 553 kidney transplant recipients and 258 liver transplant recipients who received transplant procedures at the Baskent University Transplantation Center between 2008 and May 2016 were retrospectively reviewed. Fifty-one patients who were examined by an expert neurologist and diagnosed with neuropathic pain on the basis of clinical, neurologic examination, and laboratory findings were included for analyses.

RESULTS

Among 811 transplant recipients, 51 patients (6.2%) were diagnosed with neuropathic pain. Of these, 22 were female and 38 were male patients, and 42 were kidney transplant recipients and 9 were liver transplant recipients. Causes of neuropathic pain included uremia, diabetes mellitus, ischemic peripheral arterial disease, inflammatory neuropathy, vasculitis, discopathy, postherpetic neuralgia, carpal tunnel syndrome, and multiple myeloma. Patients with symptoms too mild to affect daily life activities were treated conservatively. Plasmapheresis, gabapentin, pregabalin, alpha-lipoic acid, and duloxetine were administered as treatment modalities and medications.

CONCLUSIONS

Neuropathic pain was lower in our transplant recipients than in the general population. Treatment medications were effective for transplant recipients at lower doses for the management of neuropathic pain impairing quality of life than doses for the general population.

Cardiac autonomic neuropathy in patients with diabetes mellitus: current perspectives

Cardiac autonomic neuropathy (CAN) is a common and often-underdiagnosed complication of diabetes mellitus (DM). CAN is associated with increased mortality, cardiovascular disease, chronic kidney disease, and morbidity in patients with DM, but despite these significant consequences CAN often remains undiagnosed for a prolonged period. This is commonly due to the disease being asymptomatic until the later stages, as well as a lack of easily available screening strategies. In this article, we review the latest developments in the epidemiology, pathogenesis, diagnosis, consequences, and treatments of CAN in patients with DM.

Efficacy of Administration of an Angiotensin Converting Enzyme Inhibitor for Two Years on Autonomic and Peripheral Neuropathy in Patients with Diabetes Mellitus

Aim. To evaluate the effect of quinapril on diabetic cardiovascular autonomic neuropathy (CAN) and peripheral neuropathy (DPN). Patients and Methods. Sixty-three consecutive patients with diabetes mellitus [43% males, 27 with type 1 DM, mean age 52 years (range 22-65)], definite DCAN [abnormal results in 2 cardiovascular autonomic reflex tests (CARTs)], and DPN were randomized to quinapril 20 mg/day (group A, n = 31) or placebo (group B, n = 32) for 2 years. Patients with hypertension or coronary heart disease were excluded. To detect DPN and DCAN, the Michigan Neuropathy Screening Instrument Questionnaire and Examination (MNSIQ and MNSIE), measurement of vibration perception threshold with biothesiometer (BIO), and CARTs [R-R variation during deep breathing [assessed by expiration/inspiration ratio (E/I), mean circular resultant (MCR), and standard deviation (SD)], Valsalva maneuver (Vals), 30 : 15 ratio, and orthostatic hypotension (OH)] were used. Results. In group A, E/I, MCR, and SD increased (p for all comparisons < 0.05). Other indices (Vals, 30 : 15, OH, MNSIQ, MNSIE, and BIO) did not change. In group B, all CART indices deteriorated, except Vals, which did not change. MNSIQ, MNSIE, and BIO did not change. Conclusions. Treatment with quinapril improves DCAN (mainly parasympathetic dysfunction). Improved autonomic balance may improve the long-term outcome of diabetic patients.

Targeting the Diabetic Chaperome to Improve Peripheral Neuropathy

The chaperome constitutes a broad family of molecular chaperones and co-chaperones that facilitate the folding, refolding, and degradation of the proteome. Heat shock protein 90 (Hsp90) promotes the folding of numerous oncoproteins to aid survival of malignant phenotypes, and small molecule inhibitors of the Hsp90 chaperone complex offer a viable approach to treat certain cancers. One therapeutic attribute of this approach is the selectivity of these molecules to target high affinity oncogenic Hsp90 complexes present in tumor cells, which are absent in nontransformed cells. This selectivity has given rise to the idea that disease may contribute to forming a stress chaperome that is functionally distinct in its ability to interact with small molecule Hsp90 modulators. Consistent with this premise, modulating Hsp90 improves clinically relevant endpoints of diabetic peripheral neuropathy but has little impact in nondiabetic nerve. The concept of targeting the "diabetic chaperome" to treat diabetes and its complications is discussed.

Bariatric Surgery Restores Cardiac and Sudomotor Autonomic C-Fiber Dysfunction towards Normal in Obese Subjects with Type 2 Diabetes

OBJECTIVE

The aim was to evaluate the impact of bariatric surgery on cardiac and sudomotor autonomic C-fiber function in obese subjects with and without Type 2 diabetes mellitus (T2DM), using sudorimetry and heart rate variability (HRV) analysis.

METHOD

Patients were evaluated at baseline, 4, 12 and 24 weeks after vertical sleeve gastrectomy or Roux-en-Y gastric bypass. All subjects were assessed using SudoscanTM to measure electrochemical skin conductance (ESC) of hands and feet, time and frequency domain analysis of HRV, Neurologic Impairment Scores of lower legs (NIS-LL), quantitative sensory tests (QST) and sural nerve conduction studies.

RESULTS

Seventy subjects completed up to 24-weeks of follow-up (24 non-T2DM, 29 pre-DM and 17 T2DM). ESC of feet improved significantly towards normal in T2DM subjects (Baseline = 56.71±3.98 vs 12-weeks = 62.69±3.71 vs 24-weeks = 70.13±2.88, p<0.005). HRV improved significantly in T2DM subjects (Baseline sdNN (sample difference of the beat to beat (NN) variability) = 32.53±4.28 vs 12-weeks = 44.94±4.18 vs 24-weeks = 49.71±5.19, p<0,001 and baseline rmsSD (root mean square of the difference of successive R-R intervals) = 23.88±4.67 vs 12-weeks = 38.06±5.39 vs 24-weeks = 43.0±6.25, p<0.0005). Basal heart rate (HR) improved significantly in all groups, as did weight, body mass index (BMI), percent body fat, waist circumference and high-density lipoprotein (HDL). Glycated hemoglobin (HbA1C), insulin and HOMA2-IR (homeostatic model assessment) levels improved significantly in pre-DM and T2DM subjects. On multiple linear regression analysis, feet ESC improvement was independently associated with A1C, insulin and HOMA2-IR levels at baseline, and improvement in A1C at 24 weeks, after adjusting for age, gender and ethnicity. Sudomotor function improvement was not associated with baseline weight, BMI, % body fat or lipid levels. Improvement in basal HR was also independently associated with A1C, insulin and HOMA2-IR levels at baseline.

CONCLUSION

This study shows that bariatric surgery can restore both cardiac and sudomotor autonomic C-fiber dysfunction in subjects with diabetes, potentially impacting morbidity and mortality.