Diabetic neuropathy: scope of the syndrome

Autophagy Dysfunction in a Diabetic Peripheral Neuropathy Model

BACKGROUND

The relationship between autophagy and diabetic peripheral neuropathy (DPN) has been highlighted in few reports. Using an animal model, the authors investigated the relationship between autophagy and DPN, focused particularly on changes in autophagy in Schwann cells.

METHODS

The ultrastructural features of DPN mice were evaluated in vivo using transmission electron microscopy. Dysfunction of autophagy in DPN was evaluated using immunofluorescence microscopy and Western blot analysis of proteins related to autophagy, including Beclin1, LC3, and p62. Reactive oxygen species levels were measured in vitro in glucose-treated Schwann cells. Dysfunction of autophagy in glucose-treated Schwann cells was examined by immunofluorescence microscopy and Western blot analysis.

RESULTS

Reduced myelin thickness and axonal shrinkage were observed in the sciatic nerves of DPN mice. Reactive oxygen species levels were increased in Schwann cells treated with high glucose ( P < 0.05). The expression of Beclin1 was increased in DPN mice and Schwann cells treated with high glucose ( P < 0.05), whereas the expression of LC3-II/LC3-I ratio and p62 were decreased in DPN mice and Schwann cells treated with high glucose ( P < 0.05).

CONCLUSIONS

These results suggest that increased levels of reactive oxygen species induced by high glucose may contribute to autophagy dysfunction in Schwann cells. Autophagy dysfunction especially in Schwann cells may be an underlying cause of DPN.

CLINICAL RELEVANCE STATEMENT

This study presents the pathological mechanism of diabetic peripheral neuropathy.

Comparison of the Response to Pulpal Sensibility Tests in Well-Controlled and Uncontrolled Type II Diabetes Mellitus Patients: A Cross-Sectional Study

Introduction

Diabetes mellitus is a metabolic disorder in which impairment of sensory fibers would be anticipated. The present study would assess the dental pulp response to cold and EPT sensibility tests in patients with type 2 diabetes, both well-controlled and uncontrolled.

Materials and Methods

One hundred two maxillary central incisors, belonging to participants aged 35–67 years, were included in this survey. At last, 51 diabetic patients were allocated to each group of well-controlled (HbA1C < 7) and uncontrolled (HbA1C ≥ 7). Electric and cold pulpal vitality tests were conducted for all teeth. Statistical analysis was performed with Student's t-test, the chi-square test, and the multiple linear regression model. A P value less than 0.05 was considered significant.

Results

Based on the results of this study, the mean value of response to EPT was 4.51 ± 2.06 and 4.41 ± 1.85 in well-controlled and uncontrolled diabetic patients, respectively. Also, the pulpal responses to cold and EPT tests had no significant differences between the two groups (P > 0.05).

Conclusion

Tooth responses to the cold and EPT sensibility tests were not different in well-controlled and uncontrolled diabetic patients. Despite no statistically significant correlation, male diabetic patients in the uncontrolled group showed a lower sensory response threshold to EPT compared to a well-controlled group.

Sarm1 Gene Deficiency Attenuates Diabetic Peripheral Neuropathy in Mice

Diabetic peripheral neuropathy (DPN) is the most common complication in both type 1 and type 2 diabetes, but any treatment toward the development of DPN is not yet available. Axon degeneration is an early feature of many peripheral neuropathies, including DPN. Delay of axon degeneration has beneficial effects on various neurodegenerative diseases, but its effect on DPN is yet to be elucidated. Deficiency of Sarm1 significantly attenuates axon degeneration in several models, but the effect of Sarm1 deficiency on DPN is still unclear. In this study, we show that Sarm1 knockout mice exhibit normal glucose metabolism and pain sensitivity, and deletion of the Sarm1 gene alleviates hypoalgesia in streptozotocin-induced diabetic mice. Moreover, Sarm1 gene deficiency attenuates intraepidermal nerve fiber loss in footpad skin; alleviates axon degeneration, the change of g-ratio in sciatic nerves, and NAD⁺ decrease; and relieves axonal outgrowth retardation of dorsal root ganglia from diabetic mice. In addition, Sarm1 gene deficiency markedly diminishes the changes of gene expression profile induced by streptozotocin in the sciatic nerve, especially some abundant genes involved in neurodegenerative diseases. These findings demonstrate that Sarm1 gene deficiency attenuates DPN in mice and suggest that slowing down axon degeneration is a potential promising strategy to combat DPN.

Neuropathic-like pain in psoriatic arthritis: evidence of abnormal pain processing

OBJECTIVES

The primary objective was to investigate the prevalence of neuropathic-like pain in patients with psoriatic arthritis (PsA). Secondary outcomes were to investigate whether mood, fatigue, pain, disease severity and fibromyalgia are associated with neuropathic-like pain in PsA patients.

METHODS

PsA patients were assessed for fatigue, mood, pain, disease activity and fibromyalgia using questionnaires. Neuropathic-like pain was assessed by PainDetect.

RESULTS

Sixty-four patients with PsA were recruited from the Rheumatology Outpatient Department. Of the 64 patients recruited, 26.6% had 'likely neuropathic pain' and 21.9% had 'possible neuropathic-like pain' according to the PainDetect questionnaire. Patients with 'likely neuropathic pain' had higher disease activity, health assessment questionnaire, patient global self-assessment score, tender and swollen joint counts, dactylitis, enthesitis, pain severity and interference with day-to-day activities, fatigue severity and impact, fibromyalgia, anxiety and depression than 'unlikely neuropathic pain' patients (p < 0.05). PainDetect score correlated with measures of disease activity, fatigue, depression, anxiety, Widespread Pain Index and Symptom Severity Scale (all p < 0.05). Most patients (71%) with neuropathic-like pain fulfilled American College of Rheumatology 2010 fibromyalgia criteria. Patients with 'possible neuropathic-like pain' had scores between patients with 'likely neuropathic pain' and 'unlikely neuropathic pain'.

CONCLUSION

Neuropathic-like pain as evidence of abnormal pain processing is common in patients with PsA. It is associated with higher disease activity and fibromyalgia. A significant proportion of patients had 'possible neuropathic-like' pain with intermediate disease and symptom score suggesting neuropathic-like pain as evidence of abnormal pain processing is a continuum rather than concurrent fibromyalgia. Key Points • Neuropathic pain is prevalent in psoriatic arthritis. • Higher levels of pain, disease activity, fatigue, depression, anxiety and comorbidities in Psoriatic arthritis. • Increased pain severity is associated with increased disease activity, fatigue, depression and anxiety.

Inhibitory effect of valproate sodium on pain behavior in diabetic mice involves suppression of spinal histone deacetylase 1 and inflammatory mediators

Anti-epileptic medications are included in the international guidelines for managing neuropathic pain. Valproate sodium (VPS) was recently described as "the forgotten analgesic" and has been reported to relief pain in various models of neuropathic pain. Some studies reported anti-inflammatory and histone deacetylase 1 (HDA1) inhibitory properties for sodium valproate. The aim of the current study was to investigate the modulatory effect of VPS on pain behavior and inflammatory reactions in alloxan-induced diabetic neuropathy focusing on HDA1 inhibition and glia reactivity. 28 Male Swiss albino mice were allocated into four groups, (1) vehicle group, (2) alloxan-diabetic group, (3 & 4) alloxan+VPS (25 or 50 mg/kg) groups. VPS was given daily for 5 weeks by oral gavage. Pain behavior demonstrated increased allodynia (von-Frey filaments) and hyperalgesia (hot-plate test) in alloxan-diabetic mice that was reduced significantly by at least one of VPS doses. Sciatic nerves in diabetic mice showed increased histopathology score, increased silver staining for the nerves-indicating myelopathy- and a decrease in immunostaining for nerve growth factor. Spinal cord of diabetic mice showed greater histopathologic score, increased CD11b and glia fibrillary acidic protein (GFAP) immunostaining than vehicle treated mice. Molecular investigations highlighted greater content of spinal histone deacetylases, tumor necrosis factor-α (TNF-α) and interlukin-1β (IL1β) that were favorably modified by VPS. Overall, the current data confirmed that the pain killing and anti-inflammatory activity of VPS is at least partly mediated through inhibition of spinal HDA1 and glia reactivity. These findings support the view of inviting antiepileptics for treating neuropathies.

Calcimimetic restores diabetic peripheral neuropathy by ameliorating apoptosis and improving autophagy

Decreased AMPK-eNOS bioavailability mediates the development of diabetic peripheral neuropathy (DPN) through increased apoptosis and decreased autophagy activity in relation to oxidative stress. Schwann cells are responsible for maintaining structural and functional integrity of neurons and for repairing damaged nerves. We evaluated the neuro-protective effect of cinacalcet on DPN by activating the AMPK-eNOS pathway using db/db mice and human Schwann cells (HSCs). Sciatic nerve of db/db mice was characterized by disorganized myelin, axonal shrinkage, and degeneration that were accompanied by marked fibrosis, inflammation, and apoptosis. These phenotypical alterations were significantly improved by cinacalcet treatment along with improvement in sensorimotor functional parameters. Cinacalcet demonstrated favorable effects through increased expression and activation of calcium-sensing receptor (CaSR)-CaMKKβ and phosphorylation of AMPK-eNOS signaling in diabetic sciatic nerve. Cinacalcet decreased apoptosis and increased autophagy activity in relation to decreased oxidative stress in HSCs cultured in high-glucose medium as well. This was accompanied by increased expression of the CaSR, intracellular Ca⁺⁺ ([Ca⁺⁺]i) levels, and CaMKKβ-LKB1-AMPK signaling pathway, resulting in the net effect of increased eNOS phosphorylation, NOx concentration, Bcl-2/Bax ratio, beclin 1, and LC3-II/LC3-I ratio. These results demonstrated that cinacalcet treatment ameliorates inflammation, apoptosis, and autophagy through increased expression of the CaSR, [Ca⁺⁺]i levels and subsequent activation of CaMKKβ-LKB-1-AMPK-eNOS pathway in the sciatic nerve and HSCs under diabetic condition. Therefore, cinacalcet may play an important role in the restoration and amelioration of DPN by ameliorating apoptosis and improving autophagy.

Smart Wound Dressings for Diabetic Chronic Wounds

Given their severity and non-healing nature, diabetic chronic wounds are a significant concern to the 30.3 million Americans diagnosed with diabetes mellitus (2015). Peripheral arterial diseases, neuropathy, and infection contribute to the development of these wounds, which lead to an increased incidence of lower extremity amputations. Early recognition, debridement, offloading, and controlling infection are imperative for timely treatment. However, wound characterization and treatment are highly subjective and based largely on the experience of the treating clinician. Many wound dressings have been designed to address particular clinical presentations, but a prescriptive method is lacking for identifying the particular state of chronic, non-healing wounds. The authors suggest that recent developments in wound dressings and biosensing may allow for the quantitative, real-time representation of the wound environment, including exudate levels, pathogen concentrations, and tissue regeneration. Development of such sensing capability could enable more strategic, personalized care at the onset of ulceration and limit the infection leading to amputation. This review presents an overview of the pathophysiology of diabetic chronic wounds, a brief summary of biomaterial wound dressing treatment options, and biosensor development for biomarker sensing in the wound environment.

Functional status mediates the association between peripheral neuropathy and health-related quality of life in individuals with diabetes

AIMS

To examine differences in health-related quality of life (HRQoL) between patients with and without diabetic peripheral neuropathy (DPN), and whether these differences can be explained by functional deficits.

METHODS

This was a cross-sectional study of 160 patients with type 2 diabetes mellitus, 80 with DPN and 80 without. Assessments included HRQoL (health utility score derived from EQ-5D-5L), functional status measurements [muscle strength, timed up and go (TUG), five times sit-to-stand (FTSTS), functional reach, body sway velocity] and self-reported balance confidence [Activities-specific Balance Confidence (ABC) scale].

RESULTS

Mean utility scores were 0.67 ± 0.14 and 0.77 ± 0.16 in patients with and without DPN, respectively (p < 0.001). Patients with DPN had lower great toe extensor strength (6.4 ± 1.8 vs 7.6 ± 2.8 lbs, p = 0.001), greater body sway velocity (2.40 ± 1.31 vs 1.90 ± 0.52 mm/s, p = 0.002), slower TUG (12.1 ± 4.6 vs 10.1 ± 2.3 s, p < 0.001) and FTSTS (15.8 ± 5.8 vs 13.9 ± 5.4 s, p = 0.03) scores, and lower ABC score (73.4 ± 21.3 vs 82.6 ± 16.9, p = 0.003), compared to those without DPN. On stepwise multiple regression, DPN status, FTSTS, body sway velocity, BMI, diabetes duration, pain, and gender explained 38% of HRQoL variance. Addition of ABC score into the model explained 45% of variance. Results from structural equation modelling showed that DPN had direct effects on HRQoL and indirect effects through FTSTS, body sway velocity, and ABC score, with χ ² = 8.075 (p = 0.044), root mean square error of approximation = 0.103 (lower bound 0.015, upper bound 0.191), Comparative Fit Index = 0.966, Tucker-Lewis Index = 0.887, and Standardized Root Mean Square Residual = 0.053.

CONCLUSIONS

Patients with DPN have worse HRQoL compared to patients without DPN, partly mediated by functional status parameters. Effective interventions targeting functional status may be beneficial in improving HRQoL in these patients.

Injury-induced gp130 cytokine signaling in peripheral ganglia is reduced in diabetes mellitus

Neuropathy is a major diabetic complication. While the mechanism of this neuropathy is not well understood, it is believed to result in part from deficient nerve regeneration. Work from our laboratory established that gp130 family of cytokines are induced in animals after axonal injury and are involved in the induction of regeneration-associated genes (RAGs) and in the conditioning lesion response. Here, we examine whether a reduction of cytokine signaling occurs in diabetes. Streptozotocin (STZ) was used to destroy pancreatic β cells, leading to chronic hyperglycemia. Mice were injected with either low doses of STZ (5×60mg/kg) or a single high dose (1×200mg/kg) and examined after three or one month, respectively. Both low and high dose STZ treatment resulted in sustained hyperglycemia and functional deficits associated with the presence of both sensory and autonomic neuropathy. Diabetic mice displayed significantly reduced intraepidermal nerve fiber density and sudomotor function. Furthermore, low and high dose diabetic mice showed significantly reduced tactile touch sensation measured with Von Frey monofilaments. To look at the regenerative and injury-induced responses in diabetic mice, neurons in both superior cervical ganglia (SCG) and the 4th and 5th lumbar dorsal root ganglia (DRG) were unilaterally axotomized. Both high and low dose diabetic mice displayed significantly less axonal regeneration in the sciatic nerve, when measured in vivo, 48h after crush injury. Significantly reduced induction of two gp130 cytokines, leukemia inhibitory factor and interleukin-6, occurred in diabetic animals in SCG 6h after injury compared to controls. Injury-induced expression of interleukin-6 was also found to be significantly reduced in the DRG at 6h after injury in low and high dose diabetic mice. These effects were accompanied by reduced phosphorylation of signal transducer and activator of transcription 3 (STAT3), a downstream effector of the gp130 signaling pathway. We also found decreased induction of several gp130-dependent RAGs, including galanin and vasoactive intestinal peptide. Together, these data suggest a novel mechanism for the decreased response of diabetic sympathetic and sensory neurons to injury.

Postural sway in diabetic peripheral neuropathy among Indian elderly

Background & objectives:

Diabetic peripheral neuropathy (DPN) is a major complication of type 2 diabetes and have long term complications on the postural control of the affected population. The objectives of this study were to evaluate postural stability in patients with DPN and to examine correlation of Michigan Neuropathy Screening Instrument (MNSI) with duration of diabetes, age and postural stability measures.

Methods:

Participants were included if they had clinical neuropathy which was defined by MNSI. Sixty one patients gave their consent to participate in the study and were evaluated on posturography for postural stability measures in four conditions. Repeated measures of analysis of variance (RANOVA) was used to analyze the changes in postural stability measures in different conditions.

Results:

An increase in mean value of postural stability measures was observed for velocity moment 20.4±1.3, 24.3±2.2, 42.3±20.7, 59±43.03, mediolateral displacement 0.21±0.10, 0.22±0.18, 0.03±0.11, 0.34±0.18, and anteroposterior displacement 0.39 ± 0.09, 0.45±0.12, 0.47±0.13, 0.51±0.20 from EO to EC, EOF, and ECF, respectively. There was a significant difference (P<0.05) in participants with DPN, with greater sway amplitude on firm and foam surface in all the conditions. Moderate correlation of MNSI with age (r=0.43) and postural stability measures were also observed.

Interpretation & conclusions:

Evaluation of postural stability in Indian DPN population suggests balance impairments on either firm and foam surfaces, with greater likelihood of fall being on foam or deformable surfaces among elderly adults with neuropathy (CTRI/2011/07/001884).

Painful diabetic neuropathy — current understanding and management for the primary care team

Primary care has an increasing role in the diagnosis and treatment of painful diabetic neuropathy (PDN), and early accurate diagnosis and intervention can greatly improve the prognosis. With the incidence of diabetes predicted to increase dramatically, the number of patients with PDN is set to soar. PDN can have a serious impact on quality of life, leading to severe depression and even suicide. The evolution of a schematic approach to the diagnosis and treatment of PDN can offer new hope to many patients. This review focuses on PDN and current treatment strategies. Many leading pain clinics have adopted a multidisciplinary approach to the pharmacological and non-pharmacological management of PDN.

MicroRNA 146a locally mediates distal axonal growth of dorsal root ganglia neurons under high glucose and sildenafil conditions

Axonal loss contributes to induction of diabetic peripheral neuropathy. Sildenafil, a phosphodiesterase type 5 inhibitor, ameliorates neurological dysfunction in diabetic peripheral neuropathy. However, the direct effect of high glucose and sildenafil on axonal growth has not been extensively investigated. Using rat primary dorsal root ganglia (DRG) neurons cultured in a microfluidic chamber, we investigated the effect of axonal application of high glucose and sildenafil on distal axonal growth. We found that axonal, but not cell body, application of high glucose locally inhibited distal axonal growth. However, axonal application of sildenafil overcame high glucose-reduced axonal growth. Quantitative real-time RT-PCR (qRT-PCR) and Western blot analysis of distal axonal samples revealed that high glucose reduced axonal miR-146a levels and substantially increased miR-146a target genes, IRAK1 and TRAF6 in the axon. In contrast, sildenafil significantly reversed high glucose-reduced miR-146a levels and high glucose-increased IRAK1 and TRAF6. Gain- and loss-of function of miR-146a in DRG neurons revealed that miR-146a mediated the local effect of high glucose on the distal axonal growth. These in vitro data provide new insights into molecular mechanisms of diabetic peripheral neuropathy.

Significance of functional GRP78 polymorphisms in predicting the onset of type 2 diabetic peripheral neuropathy in Chinese population

OBJECTIVE

The objective of this study is to investigate the significance of functional GRP78 polymorphisms in predicting the risk of type 2 diabetic peripheral neuropathy in Chinese population.

METHODS

Between the years of 2006 and 2010, a total of 295 definitely diagnosed type 2 diabetes mellitus (T2DM) patients were included into our study cohort and followed for 3 years. At baseline and annual re-examinations, the patients underwent physical examinations, laboratory tests and evaluation of Michigan diabetic neuropathy score (MDNS). Age, gender, disease course, waist-hip circumference ratio (WHR), body mass index (BMI), triglycerine (TG), total cholesterol (Tch), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), glycosylated haemoglobin (HbA1c), uric acid elimination rate (UAER) and uric acid (UA) were recorded and GRP78 polymorphisms were tested by direct sequencing. The prognostic significance of GRP78 polymorphisms were analysed using monovariate and multivariate logistic regression.

RESULTS

Three years after baseline, 32.9% (97/295) of the T2DM patients had suffered the development of diabetic peripheral neuropathy and GRP78 rs391957 promoter polymorphism is a significant risk factor for the onset of type 2 diabetic peripheral neuropathy. In monovariate regression model, the OR values of GRP78 rs391957 promoter polymorphism were 2.233 (C/T) and 2.734 (T/T). As for the model calibrated with demographic and laboratory indexes, the OR values were, respectively, 2.124 (C/T) and 2.423 (T/T).

CONCLUSION

Our study suggested that the GRP78 rs391957 promoter polymorphism is a potential risk factor for type 2 diabetic peripheral neuropathy.

Ethnic Differences in Geriatric Conditions and Diabetes Complications Among Older, Insured Adults With Diabetes: The Diabetes and Aging Study

OBJECTIVE

The aim of this study was to evaluate ethnic differences in burden of prevalent geriatric conditions and diabetic complications among older, insured adults with diabetes.

METHOD

An observational study was conducted among 115,538 diabetes patients, aged ≥60, in an integrated health care system with uniform access to care.

RESULTS

Compared with Whites, Asians and Filipinos were more likely to be underweight but had substantively lower prevalence of falls, urinary incontinence, polypharmacy, depression, and chronic pain, and were least likely of all groups to have at least one geriatric condition. African Americans had significantly lower prevalence of incontinence and falls, but higher prevalence of dementia; Latinos had a lower prevalence of falls. Except for end-stage renal disease (ESRD), Whites tended to have the highest rates of prevalent diabetic complications.

DISCUSSION

Among these insured older adults, ethnic health patterns varied substantially; differences were frequently small and rates were often better among select minority groups, suggesting progress toward the Healthy People 2020 objective to reduce health disparities.

Glycemic targets and medication limitations for type 2 diabetes mellitus in the older adult

OBJECTIVE

To review the optimal management of type 2 diabetes mellitus (T2DM) in the older adult.

DATA SOURCES

A PubMed search was completed to identify publications in the English language from 1947 to 2013 using combinations of the search terms: geriatrics, aged, diabetes mellitus, and type 2 diabetes mellitus. References of articles were also reviewed for inclusion if not identified in the PubMed search.

STUDY SELECTION AND DATA EXTRACTION

Original studies, clinical reviews, and guidelines were identified and evaluated for clinical relevance.

DATA SYNTHESIS

Although the number of older adults with T2DM is growing, evidence for the treatment of T2DM in this population is lacking. Barriers such as polypharmacy, comorbid conditions, economic limitations, cognitive impairment, and increased risk of hypoglycemia may limit optimal glycemic control in older adults. Several organizations provide recommendations for glycemic targets and recommend using standard glycemic goals in most healthy older adults. However, less stringent goals are necessary in certain older populations such as those patients with limited life expectancy and severe hypoglycemia. In general, glycemic goals should be individualized in older patients. Age-related pharmacokinetic and pharmacodynamic changes, comorbid conditions, adverse drug reactions, ease of medication administration, and cost of medications necessitate the need to individualize pharmacologic therapy.

CONCLUSION

Glycemic targets and medication use for T2DM should be individualized in older adults.

Clinical value of tapentadol extended-release in painful diabetic peripheral neuropathy

Painful diabetic peripheral neuropathy is difficult to treat, partially because the underlying mechanism of pain is not fully understood. Various treatment guidelines recommend first-line agents, such as α2-δ ligands, serotonin-norepinephrine reuptake inhibitors, and tricyclic antidepressants but combination therapy of alternative agents including opiates is often warranted. Tapentadol extended-release has a novel dual mechanism of action; it is both a mu-opioid receptor agonist and a norephinephrine reuptake inhibitor. It has been in the spotlight since it was FDA-approved specifically for the treatment of painful diabetic peripheral neuropathy in 2012. Previous reviews of tapentadol have focused on chronic pain. The purpose of this review article is to assess the efficacy and safety of tapentadol extended-release in adult populations with painful diabetic peripheral neuropathy and provide guidance for formulary decisions.

Computerized Dynamic Posturography in Patients with Diabetic Peripheral Neuropathy and Visual Feedback-Based Balance Training Effects

BACKGROUND: Diabetic peripheral neuropathy (DPN) often has reduced stability during standing conditions.AIM: To compare balance control in diabetic patients and normal subjects using computerized dynamic posturography and to assess effect of visual feedback-based balance training in DPN.MATERIALS AND METHODS: A total of 57 patients of type 2 diabetes mellitus and 30 age-matched normal control subjects were recruited. The sensory organization test was done before and after the training program.RESULTS: There was a significant decrease of mean (± SD) of composite equilibrium score and somatosensory ratio score between subgroups of DPN and control healthy group (p < 0.05).  There was a significant increase of mean (± SD) of composite equilibrium score and the somatosensory ratio score after treatment as compared to results before training (p < 0.05) in mild DPN.  Moreover, there were a significant correlation between composite equilibrium score and disease duration before training in the severe DPN (r = 0.368, p < 0.05). CONCLUSIONS: Computerized dynamic posturography is an important quantitative tool in the assessment of posture instability and allows for early disclosure of the failure of the postural control system. Visual feedback-based balance training was shown to be a promising method for fall prevention among early diabetes mellitus with peripheral neuropathy.

Therapeutic effects of fenofibrate on diabetic peripheral neuropathy by improving endothelial and neural survival in db/db mice

Neural vascular insufficiency plays an important role in diabetic peripheral neuropathy (DPN). Peroxisome proliferative-activated receptor (PPAR)α has an endothelial protective effect related to activation of PPARγ coactivator (PGC)-1α and vascular endothelial growth factor (VEGF), but its role in DPN is unknown. We investigated whether fenofibrate would improve DPN associated with endothelial survival through AMPK-PGC-1α-eNOS pathway. Fenofibrate was given to db/db mice in combination with anti-flt-1 hexamer and anti-flk-1 heptamer (VEGFR inhibition) for 12 weeks. The db/db mice displayed sensory-motor impairment, nerve fibrosis and inflammation, increased apoptotic cells, disorganized myelin with axonal shrinkage and degeneration, fewer unmyelinated fibers, and endoneural vascular rarefaction in the sciatic nerve compared to db/m mice. These findings were exacerbated with VEGFR inhibition in db/db mice. Increased apoptotic cell death and endothelial dysfunction via inactivation of the PPARα-AMPK-PGC-1α pathway and their downstream PI3K-Akt-eNOS-NO pathway were noted in db/db mice, human umbilical vein endothelial cells (HUVECs) and human Schwann cells (HSCs) in high-glucose media. The effects were more prominent in response to VEGFR inhibition. In contrast, fenofibrate treatment ameliorated neural and endothelial damage by activating the PPARα-AMPK-PGC-1α-eNOS pathway in db/db mice, HUVECs and HSCs. Fenofibrate could be a promising therapy to prevent DPN by protecting endothelial cells through VEGF-independent activation of the PPARα-AMPK-PGC-1α-eNOS-NO pathway.

Multichannel surface electrodes increase the sensitivity of diagnosis of neuropathy in diabetic patients

This prospective study investigated the diagnostic sensitivity of a novel multichannel surface electrode for detecting electrophysiologic changes in symptomatic diabetic neuropathy. We recruited healthy subjects without neuropathic complaints and diabetic patients with distal symmetric sensory symptoms who had normal nerve conduction studies (NCS). Eight compound muscle action potentials (CMAPs) were recorded using a multichannel electrode from each subject's abductor pollicis brevis muscle by stimulating the median nerve at the wrist. Latency- and amplitude-related variables were obtained and analyzed to compare the two groups. We used the Classification and Regression Tree (CART) algorithm to determine the cut-off values for selected predictors of diabetic neuropathy. All of the variables related to CMAP latency showed statistically significant differences between the median values for the diabetic group and the healthy control group. For example, the median value of the maximum latency and standard deviation of the eight CMAP onset latencies in diabetic patients (3.82ms and 0.15ms, respectively) were significantly larger than those in controls (3.26ms and p<0.001; 0.09ms and p<0.001, respectively). The CART analysis revealed that these variables were the most sensitive and specific variables for discriminating between patients with diabetic neuropathy and normal subjects. The multichannel surface electrode demonstrated both high sensitivity and specificity in detecting neurophysiologic abnormality of diabetic neuropathy, even when conventional NCS did not detect the abnormality.

Evaluation of an intra-institutional diabetes disease management program for the glycemic control of elderly long-term care diabetic patients

AIM

Increasing numbers of nursing home elderly patients suffer from diabetes requiring individually optimized glycemic control. This is a complicated challenge because of their high comorbidity level, and heterogeneous and changing eating status varying from independent to dysphagia and enteral feeding. In order to cope with these complex needs, we developed and implemented a diabetes disease management program. The purpose of the present study was to evaluate this program.

METHODS

We used the point prevalence approach by checking for fasting blood glucose, glycated hemoglobin and other routine biochemical tests. Eating status was evaluated by the Functional Outcome Swallowing Scale. Details about the diabetes disease management program are given in the text.

RESULTS

A total of 86 (36%) of the 234 patients on the study day were diabetics. Of these, 80 were eligible for the study. Their mean fasting blood glucose was 143.1 ± 60.6 mg/dL. The mean glycated hemoglobin level was 7.23 ± 1.39%.

CONCLUSION

No case of hypoglycemia was detected on the examination day, or during the preceding 3 weeks. No significant difference was found among the different Functional Outcome Swallowing Scale categories. These results are within satisfactory range for this category of patients suggesting that our diabetes disease management program contributes to a better glycemic control.

Serial anthropometry predicts peripheral nerve dysfunction in a community cohort

BACKGROUND

Obesity is a risk factor for glucose intolerance, but the independent role of obesity in the development of peripheral neuropathy is unclear. This study assessed the impact of body size trajectories on prevalent nerve dysfunction in community-dwelling women with and without glucose intolerance.

METHODS

Annual (1996-2008) anthropometric measures of weight, height, waist circumference and body mass index [BMI, weight (kg)/height (m(2) )] were assessed in the Study of Women's Health Across the Nation - Michigan site. Glucose intolerance was defined annually on the basis of current use of diabetes medications, self-reported diabetes diagnosis and, when available, fasting glucose. Peripheral nerve dysfunction in 2008 was defined as abnormal monofilament testing or ≥4 symptoms or signs. Linear mixed models were used to determine trajectories of anthropometry by subsequently identified nerve dysfunction status.

RESULTS

Mean BMI was 32.4 kg/m(2) at baseline, and 27.8% of the women had nerve dysfunction in 2008. BMI, weight and waist circumference increased over time. Women who would have nerve dysfunction were significantly larger than women without dysfunction, independent of glucose intolerance. At mean baseline age of 46, BMI, weight and waist circumference differed significantly (p-value < 0.01) by subsequent nerve dysfunction status, independent of glucose intolerance and hypertension. These body size differences were maintained but not exacerbated over time.

CONCLUSIONS

Peripheral nerve dysfunction is prevalent among community-dwelling women. Twelve years before the nerve assessment, anthropometry differed between women who would and would not have nerve dysfunction, differences that were maintained over time. Obesity deserves attention as an important and potentially modifiable risk factor for peripheral nerve dysfunction.

Chinese herbal medicine in treatment of diabetic peripheral neuropathy: a systematic review and meta-analysis

AIM OF STUDY

There are multimodal and multidisciplinary approaches to treat diabetic peripheral neuropathy (DPN). However, the intractable adverse effects limited their widespread use. Chinese herbal medicine (CHM) is increasingly used for the treatment of DPN. The aim of this study was to review existing evidence on the effectiveness of CHM for the treatment of DPN.

MATERIALS AND METHODS

Searches were performed with Medline, Embase, Cochrane Central Register of Controlled Trials, CNKI, CBM and Wangfan databases. Controlled trials comparing CHM with other medicine for the treatment of DPN were analyzed.

RESULTS

Eighteen trials met the inclusion criteria. All trials used vitamin B12 and/or B1 as control. Clinical therapeutic effect, divided by three grades including marked effective, effective and ineffective according to the improved degree of subjective symptom, tendon reflex, and nerve conduction velocity, was the only end point reported in all trials, and thus evaluated. The results showed CHM treatment was associated with a superiority in marked effective (odds ratio [OR], 2.40; 95% confidence interval [CI]: 0.94 to 2.97; p<0.001), and effective (OR, 1.39; 95% CI: 1.16 to 1.67; p<0.001). Patients who received CHM treatment was associated with a less likely to report ineffective (OR, 0.26; 95% CI: 0.21 to 0.33, p<0.001). No adverse events were reported in any of the included trials.

CONCLUSIONS

According to the pooled results of our study and the poor quality of the included trials, it might be uncertainty that there was a superiority of CHM for treating DPN. More rigorous controlled trials are required to substantiate or refute these early findings.

Similar pattern of peripheral neuropathy in mouse models of type 1 diabetes and Alzheimer's disease

There is an increasing awareness that diabetes has an impact on the CNS and that diabetes is a risk factor for Alzheimer's disease (AD). Links between AD and diabetes point to impaired insulin signaling as a common mechanism leading to defects in the brain. However, diabetes is predominantly characterized by peripheral, rather than central, neuropathy, and despite the common central mechanisms linking AD and diabetes, little is known about the effect of AD on the peripheral nervous system (PNS). In this study, we compared indexes of peripheral neuropathy and investigated insulin signaling in the sciatic nerve of insulin-deficient mice and amyloid precursor protein (APP) overexpressing transgenic mice. Insulin-deficient and APP transgenic mice displayed similar patterns of peripheral neuropathy with decreased motor nerve conduction velocity, thermal hypoalgesia, and loss of tactile sensitivity. Phosphorylation of the insulin receptor and glycogen synthase kinase 3β (GSK3β) was similarly affected in insulin-deficient and APP transgenic mice despite significantly different blood glucose and plasma insulin levels, and nerve of both models showed accumulation of Aβ-immunoreactive protein. Although diabetes and AD have different primary etiologies, both diseases share many abnormalities in both the brain and the PNS. Our data point to common deficits in the insulin-signaling pathway in both neurodegenerative diseases and support the idea that AD may cause disorders outside the higher CNS.

Xerosis of the feet: a comparative study on the effectiveness of two moisturizers

The treatment for xerosis (dry skin) is the repeated use of moisturizers to hydrate the skin. Their use is based on sound evidence of the importance of maintaining the skin's water content. Although the skin on the plantar surface of the foot is very thick, it is highly visco-elastic and copes with high levels of frictional, compressive and shear stresses applied to it by being supple and well hydrated. Problems arise when the skin becomes dry and loses its elastic properties. Fissures can occur which are often painful and can act as portals for infection. This article describes a double-blind clinical study to evaluate and compare the effectiveness of two commonly used moisturizers and to see if one was significantly better than the other at hydrating the skin of the feet. The two creams used were Aqueous Cream BP and CCS Foot Care Cream. Skin hydration levels were measured before any application of moisturizer and again after two weeks of twice daily application. Results showed that the regular use of both moisturizers had a significant hydrating effect on the skin. However, CCS Foot Care Cream had a significantly greater hydrating effect than Aqueous Cream BP.

Selective responses of myenteric neurons to oxidative stress and diabetic stimuli

BACKGROUND

Diabetes has a differential effect on different subpopulations of myenteric neurons. Our aim was to investigate an in vitro model to examine the pathways underlying the development of nerve changes in diabetes.

METHODS

The proportions of neuronal cell bodies containing vasoactive intestinal polypeptide (VIP), neuronal nitric oxide synthase (nNOS) and calbindin relative to the pan-neuronal marker HuC/D were quantified in wholemount preparations of the myenteric plexus of adult rat ileum using double labeling immunohistochemistry. Preparations were maintained in culture for 24 h in the presence and absence of stimuli mimicking the diabetic environment including oxidative stress, carbonyl stress, high glucose and advanced glycation end products (AGEs). Data were compared with the effect of streptozotocin-induced diabetes in vivo. KEY RESULTS Only oxidative stress in vitro produced the same pattern as observed in diabetes with an increase in VIP-, decrease in nNOS-, and no change in calbindin-positive neurons. Carbonyl stress and high glucose caused an increase in VIP-containing neurons without affecting nNOS expression. In contrast, exposure to AGEs only caused a decrease in nNOS-positive neurons. Calbindin expression was unaffected by any of the stimuli. The effects of the stimuli were prevented by the antioxidant, α-lipoic acid, or the carbonyl scavenger, aminoguanidine.

CONCLUSIONS & INFERENCES

The results provide evidence that oxidative stress is the common factor in the development of neuronal changes in diabetes; however, the mechanism by which oxidative stress occurs depends on the individual subpopulation of myenteric neurons examined. The presence of calbindin appears to protect myenteric neurons against harmful stimuli.

Impaired sensory nerve function and axon morphology in mice with diabetic neuropathy

Diabetes is the most prevalent metabolic disorder in the United States, and between 50% and 70% of diabetic patients suffer from diabetes-induced neuropathy. Yet our current knowledge of the functional changes in sensory nerves and their distal terminals caused by diabetes is limited. Here, we set out to investigate the functional and morphological consequences of diabetes on specific subtypes of cutaneous sensory nerves in mice. Diabetes was induced in C57Bl/6 mice by a single intraperitoneal injection of streptozotocin. After 6-8 wk, mice were characterized for behavioral sensitivity to mechanical and heat stimuli followed by analysis of sensory function using teased nerve fiber recordings and histological assessment of nerve fiber morphology. Diabetes produced severe functional impairment of C-fibers and rapidly adapting Aβ-fibers, leading to behavioral hyposensitivity to both mechanical and heat stimuli. Electron microscopy images showed that diabetic nerves have axoplasm with more concentrated organelles and frequent axon-myelin separations compared with control nerves. These changes were restricted to the distal nerve segments nearing their innervation territory. Furthermore, the relative proportion of Aβ-fibers was reduced in diabetic skin-nerve preparations compared with nondiabetic control mice. These data identify significant deficits in sensory nerve terminal function that are associated with distal fiber loss, morphological damage, and behavioral hyposensitivity in diabetic C57Bl/6 mice. These findings suggest that diabetes damages sensory nerves, leading to functional deficits in sensory signaling that underlie the loss of tactile acuity and pain sensation associated with insensate diabetic neuropathy.

Geriatric conditions develop in middle-aged adults with diabetes

BACKGROUND

Geriatric conditions, collections of symptoms common in older adults and not necessarily associated with a specific disease, increase in prevalence with advancing age. These conditions are important contributors to the complex health status of older adults. Diabetes mellitus is known to co-occur with geriatric conditions in older adults and has been implicated in the pathogenesis of some conditions.

OBJECTIVE

To investigate the prevalence and incidence of geriatric conditions in middle-aged and older-aged adults with diabetes.

DESIGN

Secondary analysis of nationally-representative, longitudinal health interview survey data (Health and Retirement Study waves 2004 and 2006).

PARTICIPANTS

Respondents 51 years and older in 2004 (n=18,908).

MAIN MEASURES

Diabetes mellitus. Eight geriatric conditions: cognitive impairment, falls, incontinence, low body mass index, dizziness, vision impairment, hearing impairment, pain.

KEY RESULTS

Adults with diabetes, compared to those without, had increased prevalence and increased incidence of geriatric conditions across the age spectrum (p< 0.01 for each age group from 51-54 years old to 75-79 years old). Differences between adults with and without diabetes were most marked in middle-age. Diabetes was associated with the two-year cumulative incidence of acquiring new geriatric conditions (odds ratio, 95% confidence interval: 1.8, 1.6-2.0). A diabetes-age interaction was discovered: as age increased, the association of diabetes with new geriatric conditions decreased.

CONCLUSIONS

Middle-aged, as well as older-aged, adults with diabetes are at increased risk for the development of geriatric conditions, which contribute substantially to their morbidity and functional impairment. Our findings suggest that adults with diabetes should be monitored for the development of these conditions beginning at a younger age than previously thought.

Intracellular delivery of adenosine triphosphate enhanced healing process in full-thickness skin wounds in diabetic rabbits

BACKGROUND

Small unilamellar lipid vesicles were used to encapsulate adenosine triphosphate (ATP-vesicles) for intracellular energy delivery and were tested for diabetic skin wounds in rabbits.

METHODS

Diabetes was induced by alloxan. The mean peak blood glucose concentration was 505 mg/dL. One ear was made ischemic and 80 full-thickness wounds were created in 10 animals. ATP-vesicles or saline was used and healing was compared.

RESULTS

On the non-ischemic ears, mean closure time for ATP-vesicles-treated wounds was 13.7 days versus 16.4 days for saline-treated wounds (P < .05). On the ischemic ears, mean closure time for ATP-vesicles-treated wounds was 15.3 days versus 19.3 days for saline-treated wounds (P < .01). Histological study indicated better healing and re-epithelialization in the ATP-vesicles-treated wounds.

CONCLUSIONS

Intracellular delivery of ATP accelerated the healing process of diabetic skin wounds on ischemic and non-ischemic rabbit ears. The mechanisms deserve further study but may be related to improved cellular energy supplies.

Comparison of antinociceptive and antidiabetic effects of sertraline and amitriptyline on streptozotocin-induced diabetic rats

Antidepressants (ADs) are frequently used for the treatment of persistent pain associated with diabetic neuropathy. The aim of this study is to investigate the antinociceptive effects of sertraline (Ser) and amitriptyline (Ami) in diabetic rats, and additionally monitoring their effects on grip strength, blood glucose and percentage glycosylated hemoglobin (GHb%) levels. Streptozotocin (STZ; 55 mg/kg, intraperitoneal [ip]) was injected in rats to induce diabetes. After 7 days, Ser (30 mg/kg) or Ami (15 mg/kg) was administered in diabetic rats orally. After 28 days drug treatment, the antinociceptive effects were evaluated using hot plate test both in diabetic and non-diabetic rats. The effects of these drugs on grip strength, blood glucose and GHb% were also measured. Ser and Ami showed antinociceptive effects in diabetic and non-diabetic rats. Both the drugs increased the grip strength reduction in STZ-induced diabetic rats. Ser reduces and Ami increases the serum glucose levels in diabetic and normal rats. Administration of Ami per se increased GHb% levels, while Ser per se has no effects. The effects of Ser (30 mg/kg, per os [po]) on glucose, GHb% and antinociceptive action on hot plate test showed an association between improved blood glucose levels and analgesia. However, the results of Ami treatment are controversial and needs further studies.

Clinical features and electrodiagnosis of diabetic peripheral neuropathy in the dysvascular patient

Diabetic peripheral neuropathy (DPN) is a common disorder that can lead to limb loss and death. Up to 50% of DPN patients can be asymptomatic. This fact contributes to making DPN the leading cause of lower limb amputation. The degree of heterogeneity in the clinical manifestations of DPN makes diagnosing this condition difficult. This article reviews the characteristics, diagnosis, electrodiagnosis, classification, pathogenesis, and treatment of DPN.

Human cerebral neuropathology of Type 2 diabetes mellitus

The cerebral neuropathology of Type 2 diabetes (CNDM2) has not been positively defined. This review includes a description of CNDM2 research from before the 'Pubmed Era'. Recent neuroimaging studies have focused on cerebrovascular and white matter pathology. These and prior studies about cerebrovascular histopathology in diabetes are reviewed. Evidence is also described for and against the link between CNDM2 and Alzheimer's disease pathogenesis. To study this matter directly, we evaluated data from University of Kentucky Alzheimer's Disease Center (UK ADC) patients recruited while non-demented and followed longitudinally. Of patients who had come to autopsy (N = 234), 139 met inclusion criteria. These patients provided the basis for comparing the prevalence of pathological and clinical indices between well-characterized cases with (N = 50) or without (N = 89) the premortem diagnosis of diabetes. In diabetics, cerebrovascular pathology was more frequent and Alzheimer-type pathology was less frequent than in non-diabetics. Finally, a series of photomicrographs demonstrates histopathological features (including clinical-radiographical correlation) observed in brains of persons that died after a history of diabetes. These preliminary, correlative, and descriptive studies may help develop new hypotheses about CNDM2. We conclude that more work should be performed on human material in the context of CNDM2.

Multidisciplinary approach for the treatment of diabetes in the elderly

Elderly patients living with diabetes are a highly heterogeneous population with unique care needs. Unlike younger patients, elderly patients may experience an atypical presentation and nontraditional complications of diabetes. Diabetes management and education require greater individualization in elderly adults because of differences in goals of care, risks and benefits of intensive treatment and abilities to practically carry out care regimens. A multidisciplinary approach to diabetes care requires an in-depth knowledge of diabetes, an awareness of geriatric issues and access to decision and educational support. This approach may be the most successful way of delivering individualized diabetes care. Future trials of diabetes care innovations in the elderly will be required to confirm the clinical benefits of this approach.

Improvement of motor nerve conduction velocity in diabetic rats requires normalization of the polyol pathway metabolites flux

Using ranirestat, an aldose reductase (AR) inhibitor, we investigated the relationship between sorbitol and fructose levels in the sciatic nerve and motor nerve conduction velocity (MNCV) in streptozotocin (STZ)-treated diabetic rats. Ranirestat inhibited rat and recombinant human AR with similar IC50 values and equipotently prevented sorbitol accumulation in rat erythrocytes and sciatic nerves in vitro. One week after STZ administration, sorbitol levels in rat erythrocytes and sciatic nerves significantly increased while MNCV decreased. Oral administration of ranirestat (0.03-1.0 mg/kg per day) for 3 weeks dose-dependently decreased the elevated sorbitol and fructose levels in the rat sciatic nerves without affecting blood glucose level. Particularly, at doses of 0.1 mg/kg per day or higher, ranirestat normalized both sorbitol and fructose levels in the sciatic nerves of STZ-treated rats. Ranirestat (0.1-1.0 mg/kg per day) also improved the STZ-induced decrease in MNCV in a dose-dependent manner. This improvement correlated with the decrease of sorbitol and fructose levels in the rat sciatic nerves. These findings indicate that ranirestat improves MNCV via normalization of sorbitol and fructose accumulation in the sciatic nerve.

Vascular risk factors and Alzheimer's disease

Vascular cognitive impairment risk factors include stroke, hypertension, diabetes and atherosclerosis. In the elderly, vascular risk factors occur in the presence of high levels of amyloid in the aging brain. Stroke alters the clinical expression of a given load of Alzheimer's disease (AD) pathology. Experimentally, large vessel infarcts or small striatal infarcts are larger in the presence of amyloid. Patients with minor cerebral infarcts and moderate AD lesions will develop the clinical manifestations of dementia. Moreover, there is also an association between other vascular risk factors and the clinical expression of cognitive decline and dementia. The risk of AD is increased in subjects with adult-onset diabetes mellitus, hypertension, atherosclerotic disease and atrial fibrillation. Experimentally, small striatal infarcts in the presence of high levels of amyloid in the brain exhibit a progression in infarct size over time with enhanced degree of cognitive impairment, AD-type pathology and neuroinflammation compared with striatal infarcts or high amyloid levels alone.

Appropriate application of evidence to the care of elderly patients with diabetes

Modern diabetes care may benefit a significant proportion of adults living with diabetes; however, these benefits may not be consistently realized among the heterogeneous subpopulation of elderly patients over 65 years of age. There are three clinical constraints that have been proposed as important considerations for individualizing diabetes care among elderly patients. Life expectancy should be an important determinant of the intensity of glucose control because intensive control has been found to prevent complications only after extended periods of treatment. Therefore, patients with limited life expectancy may not benefit from intensive glucose control. The time and attention of health care providers should also be considered a constrained resource that can be optimally allocated to care for elderly diabetes patients. In the face of multiple chronic conditions and symptomatic complaints, patients and their providers should prioritize diabetes care within the context of a patient's overall health care plan. The complexity of chronic medications or polypharmacy is the final clinical constraint. Polypharmacy may increase the probability of adverse drug events and represent a significant burden on quality of life. More direct clinical investigation of elderly diabetes patients will be needed if we are to truly improve the quality of life of this growing subpopulation.

Antiepileptic drugs in treatment of pain caused by diabetic neuropathy

Pain is frequent in diabetic neuropathy and is very hard to manage. Antiepileptic drugs have been used in treating pain for several decades. Their effectiveness has been described in different types of neuropathic pain, but when used as analgesics in painful diabetic neuropathy it still remains controversial. To clarify this effectiveness, a meta-analysis was performed to determine which antiepileptic drug had the best analgesic potential for managing pain in patients suffering from painful diabetic neuropathy. The search covered the Cochrane, MEDLINE, EMBASE, and LILACS databases, between January 1966 and September 2005. The following information was obtained from each article: criteria for diagnosing diabetic neuropathy, patients' age average, antiepileptic drug received and dose, sample size, duration of the disease and treatment follow-up, outcome measurement, evaluation of pain, and rescue medication. A combined 2.33 relative risk (95% confidence interval [CI] 1.88-2.88) was obtained; this result indicated that the antiepileptic drugs studied were effective for controlling pain in diabetic neuropathy. The corresponding necessary number to treat (NNT) values were established for evaluating which antiepileptic drug was most effective as an analgesic, according to our interests; pregabalin was shown to be the antiepileptic drug having the lowest NNT (NNT=3.24 and 95% CI 2.12-6.81) for achieving greater than 50% analgesia in patients suffering from painful diabetic neuropathy. Antiepileptic drugs are frequently used in the specific case of diabetic neuropathy; the combined result of this meta-analysis has demonstrated their analgesic benefit.

Effects of treatments for symptoms of painful diabetic neuropathy: systematic review

OBJECTIVE

To evaluate the effects of treatments for the symptoms of painful diabetic neuropathy.

DESIGN

Systematic review.

DATA SOURCES

Articles (English and full text) on double blind randomised trials found by searching with the key words anticonvulsant, antidepressant, non-steroidal anti-inflammatory drugs, tramadol, opioid, ion channel blocker, diabetic neuropathy, diabetic peripheral neuropathy, peripheral neuropathy, and neuropathy. The search included Medline, Embase, EMB reviews-AP Journal club, and the Cochrane central register of controlled trials.

STUDY SELECTION

Randomised controlled trials comparing topically applied and orally administered drugs with a placebo in adults with painful diabetic neuropathy.

DATA EXTRACTION

Data were extracted to examine quality of methods, characteristics of studies and patients, efficacy, and side effects. The primary outcome was dichotomous information for 50% or moderate reduction of pain. Secondary outcomes were 30% reduction of pain and withdrawals related to adverse events.

RESULTS

Odds ratios were calculated for achievement of 30%, 50%, or moderate pain relief and for withdrawals related to adverse effects. Twenty five reports were included and seven were excluded. The 25 included reports compared anticonvulsants (n=1270), antidepressants (94), opioids (329), ion channel blockers (173), N-methyl-D-aspartate antagonist (14), duloxetine (805), capsaicin (277), and isosorbide dinitrate spray (22) with placebo. The odds ratios in terms of 50% pain relief were 5.33 (95% confidence interval 1.77 to 16.02) for traditional anticonvulsants, 3.25 (2.27 to 4.66) for newer generation anticonvulsants, and 22.24 (5.83 to 84.75) for tricylic antidepressants. The odds ratios in terms of withdrawals related to adverse events were 1.51 (0.33 to 6.96) for traditional anticonvulsants, 2.98 (1.75 to 5.07) for newer generation anticonvulsants, and 2.32 (0.59 to 9.69) for tricylic antidepressants. Insufficient dichotomous data were available to calculate the odds ratios for ion channel blockers.

CONCLUSION

Anticonvulsants and antidepressants are still the most commonly used options to manage diabetic neuropathy. Oral tricyclic antidepressants and traditional anticonvulsants are better for short term pain relief than newer generation anticonvulsants. Evidence of the long term effects of oral antidepressants and anticonvulsants is still lacking. Further studies are needed on opioids, N-methyl-D-aspartate antagonists, and ion channel blockers.

In vitro evidence of glucose-induced toxicity in GnRH secreting neurons: high glucose concentrations influence GnRH secretion, impair cell viability, and induce apoptosis in the GT1-1 neuronal cell line

OBJECTIVE

To evaluate for direct toxic effects of high glucose concentrations on cellular physiology in GnRH secreting immortalized GT1-1 neurons.

DESIGN

Prospective experimental design.

SETTING

In vitro experimental model using a cell culture system.

INTERVENTION(S)

GT1-1 cells were cultured in replicates in media with two different glucose concentrations (450 mg/dL and 100 mg/dL, respectively) for varying time intervals (24, 48, and 72 hours).

MAIN OUTCOME MEASURE(S)

Effects of glucose concentrations on GnRH secretion by the GT1-1 neurons were evaluated using a static culture model. Cell viability, cellular apoptosis, and cell cycle events in GT1-1 neurons maintained in two different glucose concentrations were assessed by flow cytometry (fluorescence-activated cell sorter) using Annexin V-PI staining.

RESULT(S)

Adverse influences of high glucose concentrations on GnRH secretion and cell viability were noted in cultures maintained in high glucose concentration (450 mg/dL) culture medium for varying time intervals. A significantly higher percentage of cells maintained in high glucose concentration medium demonstrated evidence of apoptosis by a fluorescence-activated cell sorter.

CONCLUSION(S)

We provide in vitro evidence of glucose-induced cellular toxicity in GnRH secreting GT1-1 neurons. Significant alterations in GnRH secretion, reduced cell viability, and a higher percentage of apoptotic cells were observed in GT1-1 cells maintained in high (450 mg/dL) compared with low (100 mg/dL) glucose concentration culture medium.

Simplified Electrodiagnostic Criteria of Diabetic Polyneuropathy in Field Study (KCIS No. 14)

This study sought to determine the sensitivity of sural sensory action amplitude (SAP) and peroneal motor conduction velocity (MCV) for differentiating the status of other nerve conduction velocities and identifying important correlates of diabetic polyneuropathy. Subjects (n = 708) with type 2 diabetes from one community completed a preliminary questionnaire. Among the 298 subjects with positive questionnaire results, 272 completed nerve conduction tests. The means of 6 nerve conduction velocities of subjects with both SAP and MCV abnormalities were compared to those of normal controls. The mean conduction velocities of all motor and sensory nerves were slower (p < 0.05) in subjects with polyneuropathy than without polyneuropathy. Important known correlates of diabetic polyneuropathy can also be identified by this electrophysiological definition. The sural SAP and peroneal MCV together serve as a good diagnostic for diabetic polyneuropathy and can be used as a simplified criterion in field studies.

Neurotrophic modulation of myelinated cutaneous innervation and mechanical sensory loss in diabetic mice

Human diabetic patients often lose touch and vibratory sensations, but to date, most studies on diabetes-induced sensory nerve degeneration have focused on epidermal C-fibers. Here, we explored the effects of diabetes on cutaneous myelinated fibers in relation to the behavioral responses to tactile stimuli from diabetic mice. Weekly behavioral testing began prior to streptozotocin (STZ) administration and continued until 8 weeks, at which time myelinated fiber innervation was examined in the footpad by immunohistochemistry using antiserum to neurofilament heavy chain (NF-H) and myelin basic protein (MBP). Diabetic mice developed reduced behavioral responses to non-noxious (monofilaments) and noxious (pinprick) stimuli. In addition, diabetic mice displayed a 50% reduction in NF-H-positive myelinated innervation of the dermal footpad compared with non-diabetic mice. To test whether two neurotrophins nerve growth factor (NGF) and/or neurotrophin-3 (NT-3) known to support myelinated cutaneous fibers could influence myelinated innervation, diabetic mice were treated intrathecally for 2 weeks with NGF, NT-3, NGF and NT-3. Neurotrophin-treated mice were then compared with diabetic mice treated with insulin for 2 weeks. NGF and insulin treatment both increased paw withdrawal to mechanical stimulation in diabetic mice, whereas NT-3 or a combination of NGF and NT-3 failed to alter paw withdrawal responses. Surprisingly, all treatments significantly increased myelinated innervation compared with control-treated diabetic mice, demonstrating that myelinated cutaneous fibers damaged by hyperglycemia respond to intrathecal administration of neurotrophins. Moreover, NT-3 treatment increased epidermal Merkel cell numbers associated with nerve fibers, consistent with increased numbers of NT-3-responsive slowly adapting A-fibers. These studies suggest that myelinated fiber loss may contribute as significantly as unmyelinated epidermal loss in diabetic neuropathy, and the contradiction between neurotrophin-induced increases in dermal innervation and behavior emphasizes the need for multiple approaches to accurately assess sensory improvements in diabetic neuropathy.

Diabetic microvascular complications: can patients at risk be identified? A review

People with diabetes have an increased risk of developing microvascular complications, diabetic retinopathy, diabetic nephropathy and diabetic neuropathy, which, if undetected or left untreated, can have a devastating impact on quality of life and place a significant burden on health care costs. In addition, diabetic microvascular complications can reduce life expectancy. The strongest risk factors are glycaemic control and diabetes duration; however, other modifiable risk factors such as hypertension, hyperlipidaemia and smoking, and unmodifiable risk factors including age at onset of diabetes and genetic factors may all play a part. Along with the presence of external risk factors, some associations have also been noted between diabetic microvascular complications themselves. There is evidence that diabetic retinopathy in association with increased blood pressure is an important risk factor for diabetic nephropathy progression. Significant correlations have also been shown between the presence of diabetic peripheral neuropathy and the presence of background or proliferative diabetic retinopathy. Clinical trials are currently in progress looking at a number of approaches to designing treatments to prevent the adverse effects of hyperglycaemia. It is essential however, that risk factors associated with the progression and development of diabetic microvascular complications are detected and treated at an early stage in order to further reduce morbidity and mortality. Considering all three complications as interrelated may well facilitate early detection of microvascular disease. Despite good long-term glycaemic and blood pressure control, diabetes remains a major cause of blindness, renal failure and amputations. As the incidence of diabetes continues to rise, the burden of diabetic microvascular complications will increase in future, hence the need for early detection. Considering the microvascular complications of diabetes as related, and enquiring proactively about complications, may well facilitate early detection of microvascular disease.

Oral magnesium administration prevents thermal hyperalgesia induced by diabetes in rats

BACKGROUND

Peripheral neuropathy is a common complication of diabetes mellitus. It has been shown that hyperglycemia may contribute to its development but the exact pathophysiology underlying this complication is not fully understood. Since oral magnesium supplementation can normalize hyperglycemia induced by diabetes in rats, this study was designed to examine the effect of oral magnesium administration on thermal hyperalgesia in streptozocin-induced diabetic rats.

MATERIAL AND METHODS

Twenty-four male adult wistar rats were divided equally into control, magnesium-treated control, diabetic and magnesium-treated diabetic groups. In magnesium-treated diabetic rats, magnesium sulfate (10g/l) was added into the drinking water once diabetes was established (10 days after STZ injection) and continued for 8 weeks. Mg-treated control animals received magnesium sulfate in the same dose and over the same time period. The other two groups; control and diabetic animals, only received tap water. At the end of the 8 weeks, thermal pain threshold was assessed by tail flick test and magnesium and glucose plasma levels were measured in all groups.

RESULT

A significant decrease (p<0.001) in thermal pain threshold and plasma magnesium levels and an increase in plasma glucose levels (p<0.001) were seen in diabetic rats 8 weeks after diabetes induction. After 8 weeks of oral magnesium, thermal hyperalgesia was normalized and plasma magnesium and glucose levels were restored towards normal.

CONCLUSION

It is concluded that oral magnesium administration given at the time of diabetes induction may be able to restore thermal hyperalgesia, magnesium deficiency and hyperglycemia and in diabetic rats.

What Is the Proper Use of Hemoglobin A1c Monitoring in the Elderly?

Diabetes mellitus (DM) is a major health problem for the aging population. Glycemic control is fundamental to the management of diabetes, as glycemic levels are closely linked to development of diabetes-related complications. Measurement of the hemoglobin A1c (A1c) to assess chronic glycemic control is an integral component of diabetes care. Currently, there is no clear evidence that age alters the relationship between A1c and average blood glucose. The Diabetes Control and Complications trial and the United Kingdom Prospective Diabetes Study are the 2 main studies that have provided evidence leading to the widespread recommendation of A1c monitoring. The American Diabetes Association recommends achieving an A1c level of 7% or lower. However, older diabetics represent a heterogeneous population ranging from frail nursing home residents to active community-dwelling elderly with variable life expectancies. One needs to look at the individual in order to best balance risk versus benefit associated with tight glycemic control. Benefits of intensive therapy in an effort to lower A1c must always be weighed against the greater risk of disabling and unpredictable hypoglycemia, as the geriatric population is less likely to benefit from reducing the risk of microvascular complications and more likely to suffer serious adverse effects from hypoglycemia.

Two-Stage Community-Based Screening Model for Estimating Prevalence of Diabetic Polyneuropathy (KCIS No. 6)

The aim of this study was to apply a calibrated two-stage community-based design to estimate the prevalence of diabetic distal sensorimotor polyneuropathy (DPN) in Taiwan. Type 2 diabetics were identified from a population-based screening program in Keelung, Taiwan. Administration of the Neurological Symptom Score (NSS) questionnaire identified 210 DPN-positive cases of the 587 diabetic subjects tested. The accuracy of this NSS screening was tested with sensitive electrophysiological DPN diagnosis. A smaller validation study was also conducted to estimate the sensitivity and specificity of the NSS questionnaire. In the validation study, the overall prevalence rate for DPN among type 2 diabetics was 26.79%. The sensitivity, specificity, positive predictive value and negative predictive values were 73.33, 30.49, 24.72 and 75.76%, respectively. The estimates of sensitivity, specificity and positive predictive values were 75.00, 33.33 and 42.86% for old cases of diabetes, and 72.22, 29.69 and 22.41% for newly diagnosed cases. The range of prevalence rate in the main study was adjusted to 28.46-36.30% after calibration for sensitivity and specificity with the validation study data. A two-stage community-based screening model with calibration of prevalence rate was developed and enabled a cost-effective DPN prevalence rate estimate in a study with a large number of subjects.

What Is the Proper Use of Hemoglobin A1c Monitoring in the Elderly?

Diabetes mellitus (DM) is a major health problem for the aging population. Glycemic control is fundamental to the management of diabetes, as glycemic levels are closely linked to development of diabetes-related complications. Measurement of the hemoglobin A1c (A1c) to assess chronic glycemic control is an integral component of diabetes care. Currently, there is no clear evidence that age alters the relationship between A1c and average blood glucose. The Diabetes Control and Complications trial and the United Kingdom Prospective Diabetes Study are the 2 main studies that have provided evidence leading to the widespread recommendation of A1c monitoring. The American Diabetes Association recommends achieving an A1c level of 7% or lower. However, older diabetics represent a heterogeneous population ranging from frail nursing home residents to active community-dwelling elderly with variable life expectancies. One needs to look at the individual in order to best balance risk versus benefit associated with tight glycemic control. Benefits of intensive therapy in an effort to lower A1c must always be weighed against the greater risk of disabling and unpredictable hypoglycemia, as the geriatric population is less likely to benefit from reducing the risk of microvascular complications and more likely to suffer serious adverse effects from hypoglycemia.