Efficacy and safety of aldose reductase inhibitor for the treatment of diabetic cardiovascular autonomic neuropathy: systematic review and meta-analysis

Evaluating treatment options for cardiovascular autonomic neuropathy in patients with diabetes mellitus: a systematic review

Background

Cardiovascular autonomic neuropathy (CAN) is a debilitating complication of diabetes mellitus. To date, there is no systematic review on all the available drug treatments for CAN in diabetic patients, except for one review focusing on aldose reductase inhibitors.

Objective

To evaluate available drug treatment options for CAN in diabetic patients.

Methods

A systematic review was conducted with a search of CENTRAL, Embase, PubMed and Scopus from database inception till 14th May 2022. Randomised controlled trials (RCTs) of diabetic patients with CAN that investigated the effect of treatment on blood pressure, heart rate variability, heart rate or QT interval were included.

Results

Thirteen RCTs with a total of 724 diabetic patients with CAN were selected. There was a significant improvement in the autonomic indices of diabetic patients with CAN given angiotensin-converting enzyme inhibitor (ACEI) for 24 weeks (p<0.05) to two years (p<0.001), angiotensin-receptor blocker (ARB) for one year (p<0.05), single dose of beta blocker (BB) (p<0.05), omega-3 polyunsaturated fatty acids (PUFAs) for three months (p<0.05), alpha-lipoic acid (ALA) for four months (p < 0.05) to six months (p=0.048), vitamin B12 in combination with ALA, acetyl L‑carnitine (ALC), superoxide dismutase (SOD) for one year (p=0.001)  and near significant improvement in the autonomic indices of diabetic patients with CAN given vitamin E for four months (p = 0.05) compared to the control group. However, there was no significant improvement in the autonomic indices of patients given vitamin B12 monotherapy (p ≥ 0.05).

Conclusion

ACEI, ARB, BB, ALA, omega-3 PUFAs, vitamin E, vitamin B12 in combination with ALA, ALC and SOD could be effective treatment options for CAN, while vitamin B12 monotherapy might be unlikely to be recommended for the treatment of CAN due to its lack of efficacy.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13340-023-00629-x.

Diabetes-Induced Cardiac Autonomic Neuropathy: Impact on Heart Function and Prognosis

Cardiovascular autonomic neuropathy (CAN) is a severe complication of the advance stage of diabetes. More than 50% of diabetic patients diagnosed with peripheral neuropathy will have CAN, with clinical manifestations including tachycardia, severe orthostatic hypotension, syncope, and physical exercise intolerance. Since the prevalence of diabetes is increasing, a concomitant increase in CAN is expected and will reduce quality of life and increase mortality. Autonomic dysfunction is associated with reduced baroreflex sensitivity and impairment of sympathetic and parasympathetic modulation. Various autonomic function tests are used to diagnose CAN, a condition without adequate treatment. It is important to consider the control of glucose level and blood pressure as key factors for preventing CAN progression. However, altered biomarkers of inflammatory and endothelial function, increased purinergic receptor expression, and exacerbated oxidative stress lead to possible targets for the treatment of CAN. The present review describes the molecular alterations seen in CAN, diagnosis, and possible alternative treatments.

Management of diabetic neuropathy

Diabetic neuropathy is a neurodegenerative disorder that may alter both the somatic and autonomic peripheral nervous systems in the context of diabetes mellitus (DM). It is a prevalent and burdensome chronic complication of DM, that requires timely management. Optimized glycemic control (mainly for type 1 DM), multifactorial intervention (mainly for type 2 DM), with lifestyle intervention/physical exercise, and weight loss represent the basis of management for diabetic distal symmetrical polyneuropathy, and should be implemented early in the disease course. Despite better understanding of the pathogenetic mechanisms of diabetic peripheral neuropathy, there is still a stringent need for more pathogenetic-based agents that would significantly modify the natural history of the disease. The paper reviews the available drugs and current recommendations for the management of distal symmetrical polyneuropathy, including pain management, and for diabetic autonomic neuropathy. Evaluation of drug combinations that would perhaps be more efficient in slowing the progression of the disease or even reversing it, and that would provide a better pain management is still needed.

Diabetic neuropathy: A narrative review of risk factors, classification, screening and current pathogenic treatment options (Review)

Diabetic neuropathy (DN) is a frequent complication of diabetes mellitus (DM) with severe consequences as it progresses and influences all human body systems. This review discusses the risk factors for DN, the main characteristics of the clinical forms of DN, the screening methods and the current therapeutic options. Distal symmetric DN is the primary clinical form, and DM patients should be screened for this complication. The most important treatment of DN remains good glucose control, generally defined as HbA1c ≤7%. Symptomatic treatment improves life quality in diabetic patients. Pharmacological agents such as alpha (α)-lipoic acid and benfotiamine have been validated in several studies since they act on specific pathways such as increased oxidative stress (α-lipoic acid exerts antioxidant effects) and the excessive production of advanced glycosylation products (benfotiamine may inhibit their production via the normalization of glucose). Timely diagnosis of DN is significant to avoid several complications, including lower limb amputations and cardiac arrhythmias.

Current concepts in the management of diabetic polyneuropathy

Diabetic sensorimotor polyneuropathy (DSPN) is encountered in approximately one-third of people with diabetes. This, in turn, might markedly impoverish their quality of life, mainly owing to neuropathic pain and foot ulcerations. Painful DSPN might be as frequent as 25% in diabetes patients. Symptoms as a result of DSPN typically comprise pain, paresthesia and numbness in the distal lower limbs. Asymptomatic DSPN might reach 50% among patients with this condition. Unfortunately, DSPN is still not adequately diagnosed and treated. Its management has three priorities: (i) lifestyle improvement, near-normoglycemia and multifactorial cardiovascular risk intervention; (ii) pathogenesis-oriented pharmacotherapy; and (iii) symptomatic alleviation of pain. Intensive diabetes therapy showed evidence for favorable effects on the incidence and deterioration of DSPN in type 1 diabetes, but not type 2 diabetes. Among pathogenesis-oriented treatments, α-lipoic acid, actovegin, benfotiamine and epalrestat are currently authorized to treat DSPN in several countries. Symptomatic therapy uses analgesics, notably antidepressants, opioids and anticonvulsants, reducing pain by ≥50% in approximately 50% of individuals, but might be limited, particularly by central nervous system-related adverse events. Local treatment with the capsaicin 8% patch might offer an alternative. In addition to pain relief, therapy should improve sleep, mobility and quality of life. In conclusion, multimodal treatment of DSPN should consider the individual risk profile, pathogenetic treatment and pain management using pharmacotherapy (combinations, if required), as well as non-pharmacological options.

[Causes, spectrum, and treatment of the diabetic neuropathy]

BACKGROUND

Half of all diabetics are affected by a diabetic neuropathy. Microangiopathy, dysfunctional Schwann cell interactions, accumulation of toxic metabolites, and inflammatory processes all contribute to nerve damage.

OBJECTIVE

Overview and perspectives of the pathophysiology as well as the current and future treatment implications.

METHODS

Literature search (1990-2020).

RESULTS

Clinically predominant are sensory and autonomic symptoms; however, muscle weakness can occur as well. Complications such as unrecognized myocardial infarctions and the diabetic foot syndrome are potentially life-threatening and can cause major disability. The pathophysiology of neuropathies in type 1 and type 2 diabetes mellitus differs due to additional risk factors of the metabolic syndrome. To reduce the risk of neuropathy, an intensive insulin therapy is superior compared to the conventional insulin therapy. Oral antidiabetic drugs should be chosen based on individual risk profiles. Metformin can cause an iatrogenic vitamin B12 deficiency. In the treatment of neuropathic pain, the calcium channel blocker pregabalin has the highest recommendation level. The tricyclic antidepressant amitriptyline is considered to be equally effective, but it is contraindicated in autonomic dysregulation and cognitive impairment. Alternatively, the serotonin-norepinephrine reuptake inhibitor duloxetine is approved for the symptomatic treatment of diabetic neuropathies. Controversially discussed medications include alpha-lipoic acid, epalrestat, and L‑serine.

CONCLUSION

The diabetic neuropathy is frequent and causes severe complications. A good understanding of the underlying pathophysiology can contribute to the development of novel treatment strategies in the future.

Phthalazinone-Assisted C-H Amidation Using Dioxazolones Under Rh(III) Catalysis

The preparation of phthalazinone derivatives is pivotal for their utilization as pharmaceutical agents and other entities. Herein, we report the phthalazinone-assisted carbon-nitrogen bond forming reaction using dioxazolones as robust amidation sources under Rh(III) catalysis. The broad functional group tolerance and complete site-selectivity are observed. Notably, a series of transformations of synthesized compounds into biologically relevant N-heterocycles demonstrates the applicability of the developed methodology.

Antibacterial properties of 5-substituted derivatives of rhodanine-3-carboxyalkyl acids. Part II

Two series of rhodanine-3-acetic and rhodanine-3-propionic acids derivatives having benzylidene and cinnamylidene substituents with additional electron donating and withdrawing groups at the C-5 position, were synthesised. The structures of the obtained derivatives were confirmed by spectroscopic methods and their lipophilicity was screened. The crystal structures were determined for selected compounds. The antibacterial activity of the derivatives was depended on the type of carboxyalkyl group in the N-3 position and on the type of the substituent in the C-5 position. The derivatives of rhodanine-3-propionic acid demonstrated the highest activity against Gram-positive bacteria. However, none of tested derivatives showed activity against Gram-negative bacteria and yeast. We believe that the presence of the N,N-diethylamine group in the aromatic system and the number of carbon atoms in the carboxyalkyl group is more significant for the biological activity than the fact that the benzylidene or cinnamylidene substituent was present at the C-5 position.

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.

Compensatory mechanisms for methylglyoxal detoxification in experimental & clinical diabetes

OBJECTIVES

The deficit of Glyoxalase I (Glo1) and the subsequent increase in methylglyoxal (MG) has been reported to be one the five mechanisms by which hyperglycemia causes diabetic late complications. Aldo-keto reductases (AKR) have been shown to metabolize MG; however, the relative contribution of this superfamily to the detoxification of MG in vivo, particularly within the diabetic state, remains unknown.

METHODS

CRISPR/Cas9-mediated genome editing was used to generate a Glo1 knock-out (Glo1-/-) mouse line. Streptozotocin was then applied to investigate metabolic changes under hyperglycemic conditions.

RESULTS

Glo1-/- mice were viable and showed no elevated MG or MG-H1 levels under hyperglycemic conditions. It was subsequently found that the enzymatic efficiency of various oxidoreductases in the liver and kidney towards MG were increased in the Glo1-/- mice. The functional relevance of this was supported by the altered distribution of alternative detoxification products. Furthermore, it was shown that MG-dependent AKR activity is a potentially clinical relevant pathway in human patients suffering from diabetes.

CONCLUSIONS

These data suggest that in the absence of GLO1, AKR can effectively compensate to prevent the accumulation of MG. The combination of metabolic, enzymatic, and genetic factors, therefore, may provide a better means of identifying patients who are at risk for the development of late complications caused by elevated levels of MG.

Curcumin, Cardiometabolic Health and Dementia

Current research indicates curcumin [diferuloylmethane; a polyphenolic compound isolated from the rhizomes of the dietary spice turmeric (Curcuma longa)] exerts a beneficial effect on health which may be partly attributable to its anti-oxidative and anti-inflammatory properties. The aim of this review is to examine potential mechanisms of the actions of curcumin in both animal and human studies. Curcumin modulates relevant molecular target pathways to improve glucose and lipid metabolism, suppress inflammation, stimulate antioxidant enzymes, facilitate insulin signalling and reduce gut permeability. Curcumin also inhibits Aβ and tau accumulation in animal models and enhances mitochondria and synaptic function. In conclusion, in high-dose animal studies and in vitro, curcumin exerts a potential beneficial effect on cardiometabolic disease. However, human studies are relatively unconvincing. More intervention studies should be conducted with the new curcumin formulation with improved oral bioavailability.

Risk and Relevance of Insulin Pump Therapy in the Aetiology of Ketoacidosis in People with Type 1 Diabetes

OBJECTIVE

The aim of this systematic data analysis was to determine the prevalence of diabetic ketoacidosis (DKA) as well as hypoglycemic and hyperglycemic disorders during insulin pump therapy (CSII) in patients with type 1 diabetes. The main focus was to investigate whether CSII patients have more DKA than the general type 1 diabetes population.

SUBJECTS AND METHODS

This retrospective study with patients who were treated in our treatment center from 2003 to 2016 includes data from 229 patients (52.4% male, 47.6% female, 37.2±16.3 years; DKA: 93, hypoglycemia: 66, hyperglycemia: 70).

RESULTS

Intensified insulin therapy was the most common treatment regimen in the study cohort (73.4%), followed by CSII (24%). However, 32.3% of the patients with DKA were on CSII. This number of DKA cases among the insulin pump users in our study cohort was higher than the prevalence reported in a previously published study by Reichel et al. (2013; p<0.05) and in a customer database (p<0.005). Most common causes of DKA in our study cohort were patient errors (43.3%) or insulin resistance induced by an underlying infection (29.8%). Device malfunction caused 13.5% of all DKA cases with an overwhelming majority on insulin pump treatment (93%). Overall, patient errors caused more DKA cases than device malfunctions.

CONCLUSIONS

Our findings suggest that despite development of more sophisticated insulin pump devices, DKA is still more frequent with CSII than with other kinds of insulin treatment.

Targeting Select Cellular Stress Pathways to Prevent Hyperglycemia-Related Complications: Shifting the Paradigm

Despite the advances made in preventing complications of diabetes, there is still substantial residual risk. Hence the need for developing new therapeutic agents that target the various facets of the pathogenesis of complications in people with diabetes. Traditionally four general biochemical pathways had been recognized as major contributors to glucotoxicity. These include the polyol pathway, the protein kinase C (PKC) pathway, glycosylation pathway, and oxidative stress. The latter has been proposed as a common impetus of the other pathways of glucotoxicity. More recently, the cross talk between oxidative stress and other recognized cellular stresses such as endoplasmic reticulum (ER), inflammatory, and mitochondrial stresses has emerged as an important additional mechanism of glucotoxicity. The observation that targeting oxidative stress with antioxidants has been associated with unfavorable clinical outcomes and the recognition that in cell cultures antioxidants may aggravate ER stress, suggests that selective targeting of individual cellular stresses may not be sufficient for preventing glucotoxicity. Future efforts should focus on developing therapeutic agents that can ameliorate cellular stress globally by simultaneously targeting the oxidative, ER, mitochondrial, and inflammatory stresses.

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.

Loss of Glyoxalase 1 Induces Compensatory Mechanism to Achieve Dicarbonyl Detoxification in Mammalian Schwann Cells

The glyoxalase system is a highly specific enzyme system existing in all mammalian cells that is responsible for the detoxification of dicarbonyl species, primarily methylglyoxal (MG). It has been implicated to play an essential role in preventing the increased formation of advanced glycation end products under certain pathological conditions. We have established the first glyoxalase 1 knock-out model (GLO1^-/-) in mammalian Schwann cells using the CRISPR/Cas9 technique to investigate compensatory mechanisms. Neither elevated concentrations of MG nor associated protein modifications were observed in GLO1^-/- cells. Alternative detoxification of MG in GLO1^-/- is achieved by increased catalytic efficiency of aldose reductase toward hemithioacetal (product of glutathione and MG), which is most likely caused by S-nitrosylation of aldose reductase. The hemithioacetal is mainly converted into lactaldehyde, which is paralleled by a loss of reduced glutathione. Inhibition of aldose reductase in GLO1^-/- cells is associated with an increased sensitivity against MG, elevated intracellular MG levels, associated modifications, as well as increased oxidative stress. Our data suggest that aldose reductase can compensate for the loss of GLO1. This might be of clinical importance within the context of neuronal diseases caused by an impaired glyoxalase system and elevated levels of dicarbonyl species, such as MG.

Effects of aldose reductase inhibitor on microneurographically assessed peripheral sympathetic nerve activity in rats

Autonomic neuropathy, one of the serious complications of diabetes, decreases quality of life. Aldose reductase inhibitor (ARI) blocks sorbitol production, and results in prevention of damage of nerve fibers. Beneficial effects of ARI have usually been confirmed through nerve conduction velocity tests in motor and sensory nerves. On the other hand, few reports have dealt with the effects of ARI on the small fiber activity such as sympathetic nerve one. In the present study, we administered eparlestat, ARI orally for 3weeks, to streptozotocin-induced diabetic (STZ+ARI) rats, and then recorded peripheral sympathetic nervous signal detected with microneurographic technique. Action potentials (APs) and bursts of APs were detected from the recorded signal, and their rates and incidences (=rates/heart rate) were compared with those in non-diabetic control (normal) and ARI-untreated streptozotocin-induced diabetic (STZ) rats. While streptozotocin and/or epalrestat did not influence burst parameters in all the three groups, AP parameters in the STZ+ARI and normal groups were higher than those in the STZ group. However, response of AP parameters to the intravenous glucose administration (IVGA) was not large in the STZ+ARI group, similar to that of the STZ group and different from that of the normal group in which AP parameters increased after IVGA. The results suggest that epalrestat may prevent sympathetic nerve activity (SNA) from reduction under hyperglycemic and insulin-depleted conditions, that enhancement of SNA was not induced after IVGA under that condition, and that AP parameters might be useful to assess the degree of neuropathy.

Treating Diabetic Neuropathy: Present Strategies and Emerging Solutions

Diabetic peripheral neuropathies (DPN) are a heterogeneous group of disorders caused by neuronal dysfunction in patients with diabetes. They have differing clinical courses, distributions, fiber involvement (large or small), and pathophysiology. These complications are associated with increased morbidity, distress, and healthcare costs. Approximately 50% of patients with diabetes develop peripheral neuropathy, and the projected rise in the global burden of diabetes is spurring an increase in neuropathy. Distal symmetrical polyneuropathy (DSPN) with painful diabetic neuropathy, occurring in around 20% of diabetes patients, and diabetic autonomic neuropathy (DAN) are the most common manifestations of DPN. Optimal glucose control represents the only broadly accepted therapeutic option though evidence of its benefit in type 2 diabetes is unclear. A number of symptomatic treatments are recommended in clinical guidelines for the management of painful DPN, including antidepressants such as amitriptyline and duloxetine, the γ-aminobutyric acid analogues gabapentin and pregabalin, opioids, and topical agents such as capsaicin. However, monotherapy is frequently not effective in achieving complete resolution of pain in DPN. There is a growing need for head-to-head studies of different single-drug and combination pharmacotherapies. Due to the ubiquity of autonomic innervation in the body, DAN causes a plethora of symptoms and signs affecting cardiovascular, urogenital, gastrointestinal, pupillomotor, thermoregulatory, and sudomotor systems. The current treatment of DAN is largely symptomatic, and does not correct the underlying autonomic nerve deficit. A number of novel potential candidates, including erythropoietin analogues, angiotensin II receptor type 2 antagonists, and sodium channel blockers are currently being evaluated in phase II clinical trials.

The aldo-keto reductases (AKRs): Overview

The aldo-keto reductase (AKR) protein superfamily contains >190 members that fall into 16 families and are found in all phyla. These enzymes reduce carbonyl substrates such as: sugar aldehydes; keto-steroids, keto-prostaglandins, retinals, quinones, and lipid peroxidation by-products. Exceptions include the reduction of steroid double bonds catalyzed by AKR1D enzymes (5β-reductases); and the oxidation of proximate carcinogen trans-dihydrodiol polycyclic aromatic hydrocarbons; while the β-subunits of potassium gated ion channels (AKR6 family) control Kv channel opening. AKRs are usually 37kDa monomers, have an (α/β)8-barrel motif, display large loops at the back of the barrel which govern substrate specificity, and have a conserved cofactor binding domain. AKRs catalyze an ordered bi bi kinetic mechanism in which NAD(P)H cofactor binds first and leaves last. In enzymes that favor NADPH, the rate of release of NADP(+) is governed by a slow isomerization step which places an upper limit on kcat. AKRs retain a conserved catalytic tetrad consisting of Tyr55, Asp50, Lys84, and His117 (AKR1C9 numbering). There is conservation of the catalytic mechanism with short-chain dehydrogenases/reductases (SDRs) even though they show different protein folds. There are 15 human AKRs of these AKR1B1, AKR1C1-1C3, AKR1D1, and AKR1B10 have been implicated in diabetic complications, steroid hormone dependent malignancies, bile acid deficiency and defects in retinoic acid signaling, respectively. Inhibitor programs exist world-wide to target each of these enzymes to treat the aforementioned disorders. Inherited mutations in AKR1C and AKR1D1 enzymes are implicated in defects in the development of male genitalia and bile acid deficiency, respectively, and occur in evolutionarily conserved amino acids. The human AKRs have a large number of nsSNPs and splice variants, but in many instances functional genomics is lacking. AKRs and their variants are now poised to be interrogated using modern genomic and informatics approaches to determine their association with human health and disease.

Identifying Common Genetic Risk Factors of Diabetic Neuropathies

Type 2 diabetes mellitus (T2DM) is a global public health problem of epidemic proportions, with 60-70% of affected individuals suffering from associated neurovascular complications that act on multiple organ systems. The most common and clinically significant neuropathies of T2DM include uremic neuropathy, peripheral neuropathy, and cardiac autonomic neuropathy. These conditions seriously impact an individual's quality of life and significantly increase the risk of morbidity and mortality. Although advances in gene sequencing technologies have identified several genetic variants that may regulate the development and progression of T2DM, little is known about whether or not the variants are involved in disease progression and how these genetic variants are associated with diabetic neuropathy specifically. Significant missing heritability data and complex disease etiologies remain to be explained. This article is the first to provide a review of the genetic risk variants implicated in the diabetic neuropathies and to highlight potential commonalities. We thereby aim to contribute to the creation of a genetic-metabolic model that will help to elucidate the cause of diabetic neuropathies, evaluate a patient's risk profile, and ultimately facilitate preventative and targeted treatment for the individual.

Diabetes and cardiac autonomic neuropathy: Clinical manifestations, cardiovascular consequences, diagnosis and treatment

Cardiac autonomic neuropathy (CAN) is a frequent chronic complication of diabetes mellitus with potentially life-threatening outcomes. CAN is caused by the impairment of the autonomic nerve fibers regulating heart rate, cardiac output, myocardial contractility, cardiac electrophysiology and blood vessel constriction and dilatation. It causes a wide range of cardiac disorders, including resting tachycardia, arrhythmias, intraoperative cardiovascular instability, asymptomatic myocardial ischemia and infarction and increased rate of mortality after myocardial infarction. Etiological factors associated with autonomic neuropathy include insufficient glycemic control, a longer period since the onset of diabetes, increased age, female sex and greater body mass index. The most commonly used methods for the diagnosis of CAN are based upon the assessment of heart rate variability (the physiological variation in the time interval between heartbeats), as it is one of the first findings in both clinically asymptomatic and symptomatic patients. Clinical symptoms associated with CAN generally occur late in the disease process and include early fatigue and exhaustion during exercise, orthostatic hypotension, dizziness, presyncope and syncope. Treatment is based on early diagnosis, life style changes, optimization of glycemic control and management of cardiovascular risk factors. Medical therapies, including aldose reductase inhibitors, angiotensin-converting enzyme inhibitors, prostoglandin analogs and alpha-lipoic acid, have been found to be effective in randomized controlled trials. The following article includes the epidemiology, clinical findings and cardiovascular consequences, diagnosis, and approaches to prevention and treatment of CAN.

The inhibitory activity of aldose reductase in vitro by constituents of Garcinia mangostana Linn

We investigated aldose reductase inhibition of Garcinia mangostana Linn. from Indonesia. Dichloromethane extract of the root bark of this tree was found to demonstrate an IC50 value of 11.98 µg/ml for human aldose reductase in vitro. From the dichloromethane fraction, prenylated xanthones were isolated as potent human aldose reductase inhibitors. We discovered 3-isomangostin to be most potent against aldose reductase, with an IC50 of 3.48 µM.

Asiatic acid and maslinic acid protected heart via anti-glycative and anti-coagulatory activities in diabetic mice

The cardiac protective effects of asiatic acid (AA) and maslinic acid (MA) in diabetic mice were examined.