Showing neuropathy is related to increased mortality in diabetic patients - a survival analysis using an accelerated failure time model

Associations of polyneuropathy with risk of all-cause and cardiovascular mortality, cardiovascular disease events stratified by diabetes status

AIMS/INTRODUCTION

We investigated the association of polyneuropathy (PN) with all-cause and cardiovascular (CV) mortality and with cardiovascular disease (CVD) events stratified by diabetes status.

MATERIALS AND METHODS

This prospective cohort study used the UK Biobank. Polyneuropathy was defined based on nurse-led interviews or ICD codes for polyneuropathy. Cox proportional hazards models were used to investigate the association of polyneuropathy with clinical outcomes.

RESULTS

A total of 459,127 participants were included in the analysis. Polyneuropathy was significantly associated with all-cause and cardiovascular mortality, and with CVD events even after adjusting for CVD risk factors across all diabetes statuses. Metabolic parameters HbA1c , waist circumference, BMI and the inflammatory parameter C-reactive protein showed significant mediation effects for the association between polyneuropathy and CVD. Adherence to a favorable lifestyle was associated with a lower risk of all-cause and cardiovascular mortality regardless of polyneuropathy status.

CONCLUSIONS

Polyneuropathy was associated with all-cause and cardiovascular mortality, and with CVD events in subjects with diabetes or prediabetes, even those having normal glucose tolerance. This study suggests the importance of polyneuropathy as a risk factor for death and highlights the necessity of early diagnosis and lifestyle intervention for those with type 2 diabetes and polyneuropathy.

Retinopathy as an independent predictor of all-cause mortality in individuals with type 2 diabetes

AIMS

To assess whether the presence and grade of diabetic retinopathy (DR) predict all-cause mortality, independent of risk factors for cardiovascular disease (CVD) and other complications, including diabetes-related kidney disease (DKD) and CVD, in individuals with type 2 diabetes mellitus.

METHODS

Prospective cohort study that enroled 15,773 patients in 19 Italian centers in 2006-2008. DR ascertained by fundoscopy, DKD by albuminuria and estimated glomerular filtration rate, and prior CVD by hospital discharge records. All-cause mortality retrieved for 15,656 patients on 31 October 2015.

RESULTS

The adjusted risk of death was increased in patients with any DR (hazard ratio, 1.136 [95% confidence interval, 1.054;1.224] P < 0.0001), advanced DR, including severe non-proliferative and proliferative DR and diabetic macula edema (1.213 [1.097;1.340] P < 0.0001), and especially proliferative DR alone (1.381 [1.207;1.580] P < 0.0001), compared with those without DR. The impact of DR was more evident in patients without than in those with DKD or CVD. Mortality risk was increased in participants with DR alone, though much less than in those with DKD or CVD alone and particularly in those with both DR and DKD or CVD. DR grade was related to mortality in individuals without DKD or CVD, whereas it conferred no additional risk to those with albuminuric or nonalbuminuric DKD or established CVD.

CONCLUSIONS

In patients with type 2 diabetes mellitus, the excess mortality risk conferred by DR is relatively small and higher in those without DKD and CVD, suggesting that it may be mediated by the concurrent presence of these complications, even at a subclinical level.

Synergistic effect of chronic kidney disease, neuropathy, and retinopathy on all-cause mortality in type 1 and type 2 diabetes: a 21-year longitudinal study

Background

The prognostic value of common and frequently associated diabetic microvascular complications (MVC), namely chronic kidney disease (CKD), cardiac autonomic neuropathy (CAN), peripheral neuropathy (DPN), and retinopathy (DR), is well established. However, the impact of their different combinations on long-term mortality has not been adequately assessed.

Methods

We retrospectively analyzed 21-year longitudinal data from 303 patients with long-standing type 1 (T1D) or type 2 diabetes (T2D), who were thoroughly characterized at baseline for the presence of MVC using 99mTc-DTPA dynamic renal scintigraphy, overnight urine collection, cardiovascular autonomic tests, monofilament testing, and dilated fundus oculi examination.

Results

After a 5,244 person-years follow-up, a total of 133 (43.9%) deaths occurred. The presence of CKD and CAN, regardless of other MVC, increased the adjusted all-cause mortality risk by 117% (HR 2.17 [1.45–3.26]) and 54% (HR 1.54 [1.01–2.36]), respectively. Concomitant CKD&CAN at baseline were associated with the highest mortality risk (HR 5.08 [2.52–10.26]), followed by CKD&DR (HR 2.95 [1.63–5.32]), and CAN&DR (HR 2.07 [1.11–3.85]). Compared with patients free from MVC, the mortality risk was only numerically higher in those with any isolated MVC (HR 1.52 [0.87–2.67]), while increased by 203% (HR 3.03 [1.62–5.68]) and 692% (HR 7.92 [2.93–21.37]) in patients with two and three concomitant MVC, respectively.

Conclusions

Our study demonstrates the long-term, synergistic, negative effects of single and concomitant diabetic MVC on all-cause mortality, which should encourage comprehensive screenings for MCV in both T1D and T2D to improve risk stratification and treatment.

Predictive value of a novel sub-item mortality risk score derived from the Norfolk Quality of Life in Diabetic Neuropathy questionnaire in Romanian participants with diabetes mellitus

AIMS

To evaluate whether the Norfolk Quality of Life in Diabetic Neuropathy (QOL-DN) questionnaire and the novel Norfolk Mortality Risk Score (NMRS), comprising Norfolk QOL-DN items, can identify 4-year mortality risk in individuals with diabetes.

METHODS

Of 21,756 adults completing Norfolk QOL-DN in 2012, two groups of surviving and deceased patients were identified in 2016: Group 1, from a county capital and Group 2, from six small cities. NMRS was calculated in Group 1 using the 2012 scores of Norfolk QOL-DN items that discriminate between deceased and surviving participants (p &lt; 0.05) and was subsequently applied to Group 2.

RESULTS

763 participants were included (Group 1: 481 [450 surviving, 31 deceased]; Group 2: 282 [218 surviving, 64 deceased]). Total Norfolk QOL-DN score was significantly higher (worse) in deceased participants than in survivors in both groups (p ≤ 0.008). Optimal cut-off for the 25-item NMRS was 11.5 in Group 1. Individuals in Groups 1 and 2 with NMRS≥ 11.5 in 2012 had a 4-year mortality risk ratio of 4.24 (95 % confidence interval [CI]: 1.65-10.84) and 2.33 (95 % CI: 1.33-4.07), respectively, corresponding to 8 and 16 additional deaths/100 persons/4 years (p = 0.001).

CONCLUSION

Norfolk QOL-DN and NMRS can identify individuals with diabetes at risk of 4-year mortality.

Association Between HbA1c Levels and Diabetic Peripheral Neuropathy: A Case-Control Study of Patients with Type 2 Diabetes Using Claims Data

BACKGROUND

Evidence on the efficacy of glycemic control for diabetic peripheral neuropathy (DPN) is limited in patients with type 2 diabetes mellitus. Despite the known relationship between hemoglobin A1c (HbA1c) and DPN, the parameters (e.g., mean values or variability) that play an important role have not been elucidated.

OBJECTIVE

The objective of this study was to explore factors associated with DPN, including long-term HbA1c parameters, among patients with type 2 diabetes, in a large-scale longitudinal study.

METHODS

We conducted a case-control study using a medical claims database. We extracted data of patients with type 2 diabetes and disease records of DPN (indicating that they received treatment for DPN) and those without DPN records (controls), and matched for age, sex, index year, and duration since the first type 2 diabetes record. A logistic regression analysis was performed to explore factors associated with DPN, and a receiver-operating characteristic analysis to estimate the optimal mean HbA1c target.

RESULTS

Of 1,792,037 patients with type 2 diabetes, data from 1632 patients (816 per group) were analyzed. The mean HbA1c levels in the 3-year observation period were 7.2 ± 1.0% in the DPN group and 6.9 ± 1.1% in the control group. Elevated 3-year mean HbA1c levels were significantly associated with DPN records (adjusted odds ratio: 1.23, 95% confidence interval 1.06-1.42), while HbA1c variability was not significantly associated. The mean HbA1c levels that discriminated between patients with and without DPN records were 6.5% (unadjusted) and 7.1% (adjusted).

CONCLUSIONS

The development or progression of DPN in patients with type 2 diabetes was associated with the 3-year mean HbA1c level in real-world data.

The Role of Angiotensin Receptor Blockers in the Personalized Management of Diabetic Neuropathy

Neuropathy is a frequent complication of diabetes mellitus (DM) and is associated with the increased risk ofamputation and vascular events. Tight glycemic control is an important component inthe prevention of diabetic neuropathy. However, accumulating data suggest that angiotensin receptor blockers (ARBs) might also be useful in this setting. We discuss the findings of both experimental and clinical studies that evaluated the effects of ARBs on indices of diabetic neuropathy. We also review the implicated mechanisms of the neuroprotective actions of these agents. Overall, it appears that ARBs might be a helpful tool for preventing and delaying the progression of diabetic neuropathy, but more data are needed to clarify their role in the management of this overlooked complication of DM.

Modeling Survival Time to Death Among TB and HIV Co-infected Adult Patients: an Institution-Based Retrospective Cohort Study

BACKGROUND

Tuberculosis is a serious health threat, particularly for people living with human immunodeficiency virus (HIV), and HIV-positive people are more likely than others to contract the disease. Globally, tuberculosis (TB) is one of the leading causes of death among people living with HIV. The purpose of the current study was to identify factors associated with survival rates of TB/HIV co-infected patients using survival models.

METHODS

A retrospective study was conducted on TB/HIV co-infected adult patients registered and under follow-up at Tepi General Hospital (TGH) and Mizan-Tepi University Teaching Hospital (MTUTH), southwest Ethiopia. All TB/HIV co-infection patients who were registered and under follow-up from 1st January 2015 through 1st January 2020 were considered. The global Schoenfeld test was used to test the proportional hazard (PH) assumption. Various accelerated failure time (AFT) models were compared to determine the best model for the time to death of TB/HIV co-infected patients' data set. Among the most commonly used accelerated failure time models (AFT models), the study used exponential, Weibull, log-logistic, and log-lognormal AFT models. AIC and BIC were used to compare the performance of fitted models. The data were analyzed with the statistical software R.

RESULTS

Of 363 TB/HIV co-infected patients followed for 60 months, 79 (21.8%) died, while the remaining 284 (78.2%) were censored. The overall median survival time was 15.6 months. The proportional hazard assumption was checked and it was violated. In comparison to other models, the lognormal AFT model performed better. The results of the multivariable lognormal AFT model showed that age, residence, substance use, educational status, clinical stages of the disease, cluster of differentiation 4 (CD4 count/mm³), functional status, cotrimoxazole prophylactic therapy use (CPT use), and INH were all found to be significant factors, while gender, illness other than TB, and disclosure of status were insignificant variables at 5% level of significance.

CONCLUSION

Current study results revealed that older age, substance use, advanced WHO clinical stages of the disease (stage IV), bedridden functional status, and CD4 less than 200 count/mm³ were significantly associated with shorter survival time to death of HIV/TB co-infected patients while having advanced educational status, being from urban residence, CPT use, and INH significantly increase the survival time to death of TB/HIV co-infected patients. Patients with TB/HIV co-infection should be given special attention based on these important factors to improve their health and prolong their lives. HIV-positive patients are more likely than others to contract the TB disease. The risk of death among TB/HIV co-infected patients was found to be high. Out of all patients, 79 (21.8%) died. Accelerated failure time models are good alternatives for scenario Cox proportional hazard assumptions not met.

Screening, diagnosis and management of diabetic sensorimotor polyneuropathy in clinical practice: International expert consensus recommendations

Diabetic sensorimotor polyneuropathy (DSPN) affects around one third of people with diabetes and accounts for considerable morbidity, increased risk of mortality, reduced quality of life, and increased health care costs resulting particularly from neuropathic pain and foot ulcers. Painful DSPN is encountered in 13-26% of diabetes patients, while up to 50% of patients with DSPN may be asymptomatic. Unfortunately, DSPN still remains inadequately diagnosed and treated. Herein we provide international expert consensus recommendations and algorithms for screening, diagnosis, and treatment of DSPN in clinical practice derived from a Delphi process. Typical neuropathic symptoms include pain, paresthesias, and numbness particularly in the feet and calves. Clinical diagnosis of DSPN is based on neuropathic symptoms and signs (deficits). Management of DSPN includes three cornerstones: (1) lifestyle modification, optimal diabetes treatment aimed at near-normoglycemia, and multifactorial cardiovascular risk intervention, (2) pathogenetically oriented pharmacotherapy (e.g. α-lipoic acid and benfotiamine), and (3) symptomatic treatment of neuropathic pain including analgesic pharmacotherapy (antidepressants, anticonvulsants, opioids, capsaicin 8% patch and combinations, if required) and non-pharmacological options. Considering the individual risk profile, pain management should not only aim at pain relief, but also allow for improvement in quality of sleep, functionality, and general quality of life.

Bilirubin is inversely related to diabetic peripheral neuropathy assessed by sural nerve conduction study

AIMS/INTRODUCTION

Diagnosis of diabetic peripheral neuropathy (DPN) depends on subjective findings, certain investigations for DPN risks have not been performed enough. Bilirubin protects against vascular complications by reducing oxidative stress in diabetes, but is not fully tested for DPN. This study aimed to evaluate sural nerve conduction impairments (SNCI) as an objective DPN marker and the contribution of bilirubin to SNCI.

MATERIALS AND METHODS

Using DPN-Check® , SNCI was defined as a decline of amplitude potential or conduction velocity below the normal limit in 150 inpatients with diabetes. The correlations between SNCI and conventional DPN diagnosis criteria, the incidence of diabetic retinopathy/nephropathy, biomarkers for atherosclerosis, cardiac function by ultrasonic cardiogram, and bilirubin were statistically tested, followed by the comparison of logistic regression models for SNCI to find confounders with bilirubin.

RESULTS

The incidence of SNCI was 72.0%. The sensitivity and specificity of SNCI for DPN prediagnosis by simplified criteria were 54.6 and 90.5%, respectively, and similarly corresponded with diabetic retinopathy and nephropathy (sensitivity 57.4 and 50.0%, respectively). SNCI significantly related to diabetes duration, declined estimated glomerular filtration rate, albuminuria and total bilirubin. SNCI incidence was attenuated in the higher bilirubin tertiles (89.8/65.3/54.8%, P < 0.001). Bilirubin was an independent inverse risk factor for SNCI, even after adjustment by known risk factors for DPN and markers for microvascular complications.

CONCLUSIONS

SNCI is a comprehensive marker for diabetic complications. We first showed the independent inverse relationship between bilirubin and SNCI through the independent pathway with other complications, provably reducing oxidative stress, as previously reported.

Association of Nonalcoholic Fatty Liver Disease (NAFLD) with Peripheral Diabetic Polyneuropathy: A Systematic Review and Meta-Analysis

Aims. The relationship between nonalcoholic fatty liver disease (NAFLD) and diabetic polyneuropathy (DPN) has been demonstrated in many studies, although results were conflicting. This meta-analysis aims to summarize available data and to estimate the DPN risk among NAFLD patients. Materials and methods. We performed a comprehensive literature review until 4 June 2021. Clinical trials analyzing the association between NAFLD and DPN were included. Results. Thirteen studies (9614 participants) were included. DPN prevalence was significantly higher in patients with NALFD, compared to patients without NAFLD (OR (95%CI) 2.48 (1.42–4.34), p = 0.001; I2 96%). This finding was confirmed in type 2 diabetes (OR (95%CI) 2.51 (1.33–4.74), p = 0.005; I2 97%), but not in type 1 diabetes (OR (95%CI) 2.44 (0.85–6.99), p = 0.100; I2 77%). Also, body mass index and diabetes duration were higher in NAFLD subjects compared to those without NAFLD (p < 0.001), considering both type 2 and type 1 diabetes. Conclusion. Despite a high heterogeneity among studies, a significantly increased DPN prevalence among type 2 diabetes subjects with NAFLD was observed. This result was not found in type 1 diabetes, probably due to the longer duration of disease. Physicians should pay more attention to the early detection of DPN, especially in patients with NAFLD.

Oral health and all-cause, cardiovascular disease, and respiratory mortality in older people in the UK and USA

Preventing deterioration of oral health in older age can be crucial for survival. We aimed to examine associations of oral health problems with all-cause, cardiovascular disease (CVD), and respiratory mortality in older people. We used cohort data from the British Regional Health Study (BRHS) (N = 2147, 71-92 years), and the Health, Aging and Body Composition (HABC) Study (USA) (N = 3075, 71-80 years). Follow-up was 9 years (BRHS) and 15 years (HABC Study). Oral health comprised tooth loss, periodontal disease, dry mouth, and self-rated oral health. Cox regression was performed for all-cause mortality, competing risks for CVD mortality, and accelerated failure time models for respiratory mortality. In the BRHS, tooth loss was associated with all-cause mortality (hazard ratio (HR) = 1.59, 95% CI 1.09, 2.31). In the HABC Study, tooth loss, dry mouth, and having ≥ 3 oral problems were associated with all-cause mortality; periodontal disease was associated with increased CVD mortality (subdistribution hazard ratio (SHR) = 1.49, 95% CI 1.01, 2.20); tooth loss, and accumulation of oral problems were associated with high respiratory mortality (tooth loss, time ratio (TR) = 0.73, 95% CI 0.54, 0.98). Findings suggest that poor oral health is associated with mortality. Results highlight the importance of improving oral health to lengthen survival in older age.

Inflammatory biomarkers as a part of diagnosis in diabetic peripheral neuropathy

Diabetic peripheral neuropathy (DPN), a chronic neurological complication of diabetes mellitus, remains scantily addressed area of research. Many lacunae in the temporal sequence between cause and effect of DPN still remain unfilled and therefore treatment of DPN remains unsatisfactory. This is largely due to the conventional glucocentric focus to resolve the problem. This focus over hyperglycemia should be shifted to consider, chronic low grade inflammation as the major determinant in DPN. Rapidly emerging evidences from recent studies suggest that chronic low grade inflammation leads to the activation of innate immune system response, loss of insulin signaling and insulin resistance, endoplasmic reticulum stress, mitochondrial stress, leading to production of kinases like protein kinase C, mitogen activated protein kinase and jun-N-terminal kinase, pro-inflammatory cytokines and inter leukins-1b, 2, 6 and 8, tumour necrosis factor-alpha and other chemokines, leading to DPN. These biomarkers can be early predictors of DPN and therefore should be the focus of work testing their clinical utility to identify high-risk individuals as well as perhaps to target interventions. In this paper, we would like to review all the aspects of DPN, laying greater emphasis on inflammatory biomarkers as a tool for early diagnosis of DPN and the possible research approaches to address it satisfactorily.

Peripheral Neuropathy and All-Cause and Cardiovascular Mortality in U.S. Adults : A Prospective Cohort Study

BACKGROUND

Growing evidence indicates that peripheral neuropathy (PN) is common even in the absence of diabetes. However, the clinical sequelae of PN have not been quantified in the general population.

OBJECTIVE

To assess the associations of PN with all-cause and cardiovascular mortality in the general adult population of the United States.

DESIGN

Prospective cohort study.

SETTING

NHANES (National Health and Nutrition Examination Survey), 1999 to 2004.

PARTICIPANTS

7116 adults aged 40 years or older who had standardized monofilament testing for PN.

MEASUREMENTS

Cox regression to evaluate the associations of PN with all-cause and cardiovascular mortality after adjustment for demographic and cardiovascular risk factors, overall and stratified by diabetes status.

RESULTS

The overall prevalence of PN (±SE) was 13.5% ± 0.5% (27.0% ± 1.4% in adults with diabetes and 11.6% ± 0.5% in adults without diabetes). During a median follow-up of 13 years, 2128 participants died, including 488 of cardiovascular causes. Incidence rates (per 1000 person-years) of all-cause mortality were 57.6 (95% CI, 48.4 to 68.7) in adults with diabetes and PN, 34.3 (CI, 30.3 to 38.8) in adults with PN but no diabetes, 27.1 (CI, 23.4 to 31.5) in adults with diabetes but no PN, and 13.0 (CI, 12.1 to 14.0) in adults with no diabetes and no PN. In adjusted models, PN was significantly associated with all-cause mortality (hazard ratio [HR], 1.49 [CI, 1.15 to 1.94]) and cardiovascular mortality (HR, 1.66 [CI, 1.07 to 2.57]) in participants with diabetes. In those without diabetes, PN was significantly associated with all-cause mortality (HR, 1.31 [CI, 1.15 to 1.50]), but the association between PN and cardiovascular mortality was not statistically significant after adjustment (HR, 1.27 [CI, 0.98 to 1.66]).

LIMITATION

Prevalent cardiovascular disease was self-reported, and PN was defined by monofilament testing only.

CONCLUSION

Peripheral neuropathy was common and was independently associated with mortality in the U.S. population, even in the absence of diabetes. These findings suggest that decreased sensation in the foot may be an underrecognized risk factor for death in the general population.

PRIMARY FUNDING SOURCE

National Institute of Diabetes and Digestive and Kidney Diseases and National Heart, Lung, and Blood Institute of the National Institutes of Health.

The Slipping Slipper Sign: A Poor Man's Test for Severe Diabetic Peripheral Neuropathy

BACKGROUND

Neuropathic feet are at very high risk for infection and amputation. The slipping slipper sign (SSS) is elicited by a simple questionnaire test reported to detect the presence of severe diabetic peripheral neuropathy. This test can be administered by non-medical staff. In this study, subjects with and without the SSS were evaluated by nerve conduction studies (NCS) and ultrasound measurements of the right sural nerve diameters as well as with traditional scoring systems for peripheral and autonomic neuropathy.

OBJECTIVE

To demonstrate that the Slipping Slipper Sign can be used as an index of severe diabetic peripheral neuropathyMethod:This was a prospective cross sectional study in which 74 patients with diabetes (38 positive and 36 negative for SSS) underwent ultrasonography and NCS of the right sural nerve by an examiner blinded to SSS status. Findings were evaluated against demography, clinical history, anthropometry as well as traditional clinical and autonomic neuropathic scores.

RESULTS

Patients without the SSS [median (IQR) = 10.0 years (4.0-20.3)] had a significantly shorter duration of diabetes compared with those with the SSS [median (IQR) = 15.0 years (8.5-25.0)], p = 0.028. The frequencies of retinopathy (36.8% vs 2.8%, p <  0.05) and cerebrovascular accidents (18.4% vs 13.9 %, p <  0.05) were higher among those with SSS compared with those without. Differences in nerve conduction characteristics were markedly significant. The amplitude of the sural sensory nerve action potential (SNAP) was ([median (IQR)] 0 microvolts vs 4.0 microvolts (0.0-10.8) p <  0.002) between those with and without SSS, respectively whilst none of patients with SSS had a recordable SNAP vs 78% without a SSS. Similarly, maximal thickness of the right sural nerve at the ankle 3.0 mm (2.3-3.4) vs 3.5 mm (3.0-3.9), and leg 3.4 mm (2.7-3.8) vs 3.9 mm (3.3-4.2) was reduced, p <  0.01 in patients with the SSS compared with those with a negative SSS.

CONCLUSION

The SSS identifies feet with objective neurophysiological and imaging characteristics of severe neuropathy.

Prevalence and Risk Factors for Diabetic Peripheral Neuropathy Among Saudi Hospitalized Diabetic Patients: A Nested Case-Control Study

OBJECTIVE

To determine the prevalence and the risk factors of diabetic peripheral neuropathy (DPN) in hospitalized adult Saudi diabetics.

METHODS

This is a retrospective, nested case-control study conducted at King Abdulaziz Medical City (KAMC) in Riyadh, Saudi Arabia. All diabetic patients admitted to the hospital between the January 1, and December 31, 2018 were considered for inclusion in the study. Patients with DPN were identified and three controls per case were randomly selected from the remaining diabetic patients without peripheral neuropathy (PN).

RESULTS

A total of 2,096 adult diabetic patients were identified during the study period. Of these, 73 patients (3.5%) were confirmed to be suffering from DPN and 219 were included as controls. When comparing diabetic with the control cases, DPN cases were significantly older (p=0.002), had a significantly higher proportion of type 2 diabetes (p=0.023), chronic kidney disease (p<0.0001), cerebral vascular stroke (p=0.027), hypertension (p=0.005), dyslipidemia (p=0.002), peripheral vascular disease (p<0.0001), osteoarthritis (p=0.034), diabetic ketoacidosis (p=0.003), foot ulcers (p=0.006), gangrene (p=0.001), lower limb ischemia (p=0.001), increased duration with diabetic disease (p=0.031), increased BMI (p=0.003), higher serum creatinine (p<0.001) and lower serum albumin levels (p=0.035). In the multivariate logistic regression, only older age {odds ratio (OR) 1.02, 95% CI 1.01-1.04, p=0.031}, chronic kidney disease (OR 2.39, 95% CI 1.23-4.64, p=0.010) and peripheral vascular disease (OR 3.14, 95% CI 1.39-7.13, p=0.006) were independently associated with DPN.

CONCLUSION

This study identified several risk factors that contributed to the development of DPN in Saudis. These must be considered in strategies and campaigns aimed at risk reduction of cardiovascular and chronic diseases, and consequently progression of DPN.

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.

Foot ulceration and its association with mortality in diabetes mellitus: a meta-analysis

BACKGROUND

Diabetic foot ulcers portend an almost twofold increase in all-cause mortality compared with diabetes on its own.

AIM

To investigate the association between diabetic foot ulcers and risk of death.

METHODS

We performed a meta-analysis of all observational studies investigating the association between diabetic foot ulcers and all-cause mortality. Risk ratios and risk differences were pooled in a random-effects model. The I² statistic was used to quantify heterogeneity between studies.

RESULTS

Altogether, we identified 11 studies that reported 84 131 deaths from any cause in 446 916 participants with diabetes during a total of 643 499 person-years of follow-up. The crude event rate for all-cause mortality in individuals with diabetes who did not develop foot ulceration was 22% lower at 181.5 deaths (per 1000 person-years) than in those who developed foot ulcers (230.8 per 1000 person-years). Diabetic foot ulceration was associated with an increased risk of all-cause mortality (pooled relative risk 2.45, 95% CI 1.85-2.85). We did not observe any tangible differences in risk of all-cause mortality from diagnosis in studies reporting a mean duration of follow-up of ≤3 years (relative risk 2.43, 95% CI 2.27-2.61) or >3 years (relative risk 2.26, 95% CI 2.13-2.40) years. Funnel plot inspection revealed no significant publication bias among studies included in this meta-analysis.

CONCLUSIONS

Our study shows an excess rate of all-cause mortality in people with diabetic foot ulceration when compared to those without foot ulceration. It is imperative that early interventions to prevent foot ulceration and modify cardiovascular disease risk factors are put in place to reduce excess mortality.

Are we assuming too much with our statistical assumptions? Lessons learned from the ALTTO trial

BACKGROUND

Design, conduct, and analysis of randomized clinical trials (RCTs) with time to event end points rely on a variety of assumptions regarding event rates (hazard rates), proportionality of treatment effects (proportional hazards), and differences in intensity and type of events over time and between subgroups.

DESIGN AND METHODS

In this article, we use the experience of the recently reported Adjuvant Lapatinib and/or Trastuzumab Treatment Optimization (ALTTO) RCT, which enrolled 8381 patients with human epidermal growth factor 2-positive early breast cancer between June 2007 and July 2011, to highlight how routinely applied statistical assumptions can impact RCT result reporting.

RESULTS AND CONCLUSIONS

We conclude that (i) futility stopping rules are important to protect patient safety, but stopping early for efficacy can be misleading as short-term results may not imply long-term efficacy, (ii) biologically important differences between subgroups may drive clinically different treatment effects and should be taken into account, e.g. by pre-specifying primary subgroup analyses and restricting end points to events which are known to be affected by the targeted therapies, (iii) the usual focus on the Cox model may be misleading if we do not carefully consider non-proportionality of the hazards. The results of the accelerated failure time model illustrate that giving more weight to later events (as in the log rank test) can affect conclusions, (iv) the assumption that accruing additional events will always ensure gain in power needs to be challenged. Changes in hazard rates and hazard ratios over time should be considered, and (v) required family-wise control of type 1 error ≤ 5% in clinical trials with multiple experimental arms discourages investigations designed to answer more than one question.

TRIAL REGISTRATION

clinicaltrials.gov Identifier NCT00490139.

Association between deterioration in muscle strength and peripheral neuropathy in people with diabetes

AIMS

Diabetic peripheral neuropathy (DPN) is a major risk factor for sarcopenia or frailty in older patients with diabetes. In this study, we investigated the association between DPN and muscle strength in type 2 diabetes.

METHODS

DPN was assessed using the Michigan Neuropathy Screening Instrument Questionnaire (MNSI-Q) and Physical Examination (MNSI-PE) in 230 subjects with type 2 diabetes. Handgrip strength (HGS) was measured using an electronic grip strength dynamometer.

RESULTS

The prevalence of DPN was 26.4% in men and 34.7% in women. HGS was significantly lower in men with DPN compared with men without DPN (27.0 ± 9.4 vs. 29.7 ± 8.4 kg, p = 0.036). This effect was not seen in women. In men, multivariate regression analysis showed that HGS was negatively associated with the MNSI-Q (β = -1.200, p = 0.003) and MNSI-PE scores (β = -0.937, p = 0.046) and resulted in an abnormal 10-gram monofilament test score (β = -10.895, p < 0.001). However, HGS was not significantly associated with neuropathy in women.

CONCLUSIONS

Muscle strength was lower in men with DPN than in those without DPN. Assessment of muscle function may have clinical implications in the prevention of sarcopenia and frailty in men with DPN.

Usefulness of the vibration perception thresholds measurement as a diagnostic method for diabetic peripheral neuropathy: Results from the Rio de Janeiro type 2 diabetes cohort study

AIMS

To investigate the associated factors with the vibration threshold perception (VPT) in patients with type 2 diabetes and to assess whether it is useful for detection of diabetic peripheral neuropathy (DPN).

METHODS

VPTs were measured with Vibration Sensory Analyzer (VSA-3000) in 426 diabetic patients. The diagnosis of DPN was based on Neuropathy Symptom Score and Neuropathy Disability Score (NDS). ROC curve analysis and multiple linear and logistic regressions were performed to investigate the associations between VPT and DPN.

RESULTS

Values of VPT were progressively higher according to NDS stages. Age, height, diabetes duration, and mean cumulative HbA_1c exposure (partial correlation coefficients: 0.34; 0.27; 0.10; and 0.13; respectively) were the variables independently associated with VPT. Area under ROC curve of VPT for detection of DPN was 0.71 (95% CI: 0.66-0.75) and >8.9 μm was its best cut-off value. VPT, age, female sex, height, diabetes duration and mean HbA_1c levels were the independent correlates of the presence of DPN. An increased VPT triplicate the likelihood of having DPN (OR: 3.24; 95% CI: 2.05-5.11).

CONCLUSIONS

VPT, measured by an automatic device, shares common correlates with DPN and is strongly associated with its presence. VPT testing may be useful as a screening tool for DPN assessment.

Three-question set from Michigan Neuropathy Screening Instrument adds independent prognostic information on cardiovascular outcomes: analysis of ALTITUDE trial

AIMS/HYPOTHESIS

The self-administered Michigan Neuropathy Screening Instrument (MNSI) is used to diagnose diabetic peripheral neuropathy. We examined whether the MNSI might also provide information on risk of death and cardiovascular outcomes.

METHODS

In this post hoc analysis of the Aliskiren Trial in Type 2 Diabetes Using Cardio-Renal Endpoints (ALTITUDE) trial, we divided 8463 participants with type 2 diabetes and chronic kidney disease (CKD) and/or cardiovascular disease (CVD) into independent training (n = 3252) and validation (n = 5211) sets. In the training set, we identified specific questions that were independently associated with a cardiovascular composite outcome (cardiovascular death, resuscitated cardiac arrest, non-fatal myocardial infarction/stroke, heart failure hospitalisation). We then evaluated the performance of these questions in the validation set.

RESULTS

In the training set, three questions ('Are your legs numb?', 'Have you ever had an open sore on your foot?' and 'Do your legs hurt when you walk?') were significantly associated with the cardiovascular composite outcome. In the validation set, after multivariable adjustment for key covariates, one or more positive responses (n = 3079, 59.1%) was associated with a higher risk of the cardiovascular composite outcome (HR 1.54 [95% CI 1.28, 1.85], p < 0.001), heart failure hospitalisation (HR 1.74 [95% CI 1.29, 2.35], p < 0.001), myocardial infarction (HR 1.81 [95% CI 1.23, 2.69], p = 0.003), stroke (HR 1.75 [95% CI 1.20, 2.56], p = 0.003) and three-point major adverse cardiovascular events (MACE) (cardiovascular death, non-fatal myocardial infarction, non-fatal stroke) (HR 1.49 [95% CI 1.20, 1.85], p < 0.001) relative to no positive responses to all questions. Associations were stronger if participants answered positively to all three questions (n = 552, 11%). The addition of the total number of affirmative responses to existing models significantly improved Harrell's C statistic for the cardiovascular composite outcome (0.70 vs 0.71, p = 0.010), continuous net reclassification improvement (+22% [+10%, +31%], p = 0.027) and integrated discrimination improvement (+0.9% [+0.4%, +2.1%], p = 0.007).

CONCLUSIONS/INTERPRETATION

We identified three questions from the MNSI that provide additional prognostic information for individuals with type 2 diabetes and CKD and/or CVD. If externally validated, these questions may be integrated into the clinical history to augment prediction of CV events in high-risk individuals with type 2 diabetes.

The prevalence and risk factors of peripheral neuropathy among patients with type 2 diabetes mellitus; the case of Jordan

BACKGROUND

Peripheral neuropathy is one of the most common microvascular complication of diabetes mellitus. This study is conducted to determine the prevalence of diabetic peripheral neuropathy (DPN) and its associated factors among patients with type 2 diabetes mellitus in Jordan.

METHODS

A cross-sectional study was conducted at the National Center for Diabetes, Endocrinology and Genetics, Jordan. A total of 1003 patients with type 2 diabetes were recruited. Data were collected from participants during a face-to-face structured interview. DPN was assessed using the translated version of Michigan Neuropathy Screening Instrument (MNSI).

RESULTS

The overall prevalence of DPN based on MNSI was 39.5%. The most frequently reported symptoms were numbness (32.3%) and pain with walking (29.7%), while the least reported symptoms were the history of amputation (1.3%) and loss of sensation in legs/feet while walking (3.8%). Logistic regression analysis revealed that unemployment, cardiovascular disease, dyslipidemia, diabetic retinopathy and long standing DM (diabetes of ≥ 5 years) were significantly associated with DPN.

CONCLUSION

Peripheral Neuropathy is highly prevalent among Jordanian patients with type 2 diabetes mellitus. DPN was significantly associated with duration of DM, dyslipidemia, diabetic retinopathy, cardiovascular disease, and unemployment. Early detection and appropriate intervention are mandatory among high-risk groups.

Nonalcoholic fatty liver disease is associated with an increased prevalence of distal symmetric polyneuropathy in adult patients with type 1 diabetes

AIMS

Presently, data on the association between nonalcoholic fatty liver disease (NAFLD) and distal symmetric polyneuropathy in people with diabetes are scarce and conflicting. The aim of this retrospective, cross-sectional study was to examine whether NAFLD was associated with an increased prevalence of distal symmetric polyneuropathy in type 1 diabetic adults.

METHODS

We studied all white type 1 diabetic outpatients (n = 286, 42.3% male, mean age 43 ± 14 years, median diabetes duration 17 [10-30] years), who participated in a foot screening program at our adult diabetes clinic after excluding those who had excessive alcohol consumption and other known causes of chronic liver disease. NAFLD was diagnosed by ultrasonography. Distal symmetric polyneuropathy was detected using the Michigan Neuropathy Screening Instrument method and the biothesiometer Vibrotest.

RESULTS

Overall, the prevalence rates of NAFLD and distal symmetric polyneuropathy were 52.4% and 35.3%, respectively. Patients with NAFLD had a substantially increased prevalence of distal symmetric polyneuropathy compared to their counterparts without NAFLD (51.0% vs. 17.1%, p < 0.001). In univariate analysis, NAFLD was associated with an approximately 5-fold increased risk of prevalent distal symmetric polyneuropathy (odds ratio [OR] 5.32, 95% confidence interval [CI] 3.1-9.3, p < 0.001). This association remained significant even after adjustment for age, sex, diabetes duration, hemoglobin A1c, diabetic retinopathy, smoking, metabolic syndrome, chronic kidney disease and carotid artery stenoses ≥ 40% (adjusted-OR 2.23, 95% CI 1.1-4.8, p < 0.05).

CONCLUSIONS

Our results show that NAFLD, diagnosed by ultrasonography, is strongly associated with an increased risk of distal symmetric polyneuropathy in type 1 diabetic adults, independently of several cardio-metabolic risk factors.

Diabetic peripheral neuropathy may not be as its name suggests: evidence from magnetic resonance imaging

Diabetic peripheral neuropathy (DPN) affects up to 50% of patients with diabetes and is a major cause of morbidity and increased mortality. Its clinical manifestations include distressing painful neuropathic symptoms and insensitivity to trauma that result in foot ulcerations and amputations. Several recent studies have implicated poor glycemic control, duration of diabetes, hyperlipidemia (particularly hypertryglyceridaemia), elevated albumin excretion rates, and obesity as risk factors for the development of DPN. However, similar data are not available for painful DPN. Moreover, although there is now strong evidence for the importance of peripheral nerve microvascular disease in the pathogenesis of DPN, peripheral structural biomarkers of painful DPN are lacking. However, there is now emerging evidence for the involvement of the central nervous system in both painful and painless DPN afforded by magnetic resonance imaging. This review will focus on this emerging evidence for central changes in DPN, hitherto considered a peripheral nerve disease only.

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

AIMS

We aimed to analyze the impact of baseline factors on the efficacy of α-lipoic acid (ALA) over 4 years in the NATHAN 1 trial.

METHODS

This was a post-hoc analysis of the NATHAN 1 trial, a 4-year randomized study including 460 diabetic patients with mild-to-moderate polyneuropathy using ALA 600 mg qd or placebo. Amongst others, efficacy measures were the Neuropathy Impairment Score of the lower limbs (NIS-LL) and heart rate during deep breathing (HRDB).

RESULTS

Improvement and prevention of progression of NIS-LL (ΔNIS-LL≥2 points) with ALA vs. placebo after 4 years was predicted by higher age, lower BMI, male sex, normal blood pressure, history of cardiovascular disease (CVD), insulin treatment, longer duration of diabetes and neuropathy, and higher neuropathy stage. Participants treated with ALA who received ACE inhibitors showed a better outcome in HRDB after 4 years.

CONCLUSIONS

Better outcome in neuropathic impairments following 4-year treatment with α-lipoic acid was predicted by normal BMI and blood pressure and higher burden due to CVD, diabetes, and neuropathy, while improvement in cardiac autonomic function was predicted by ACE inhibitor treatment. Thus, optimal control of CVD risk factors could contribute to improved efficacy of α-lipoic acid in patients with higher disease burden.

Inflammation as a Therapeutic Target for Diabetic Neuropathies

Diabetic neuropathies (DNs) are one of the most prevalent chronic complications of diabetes and a major cause of disability, high mortality, and poor quality of life. Given the complex anatomy of the peripheral nervous system and types of fiber dysfunction, DNs have a wide spectrum of clinical manifestations. The treatment of DNs continues to be challenging, likely due to the complex pathogenesis that involves an array of systemic and cellular imbalances in glucose and lipids metabolism. These lead to the activation of various biochemical pathways, including increased oxidative/nitrosative stress, activation of the polyol and protein kinase C pathways, activation of polyADP ribosylation, and activation of genes involved in neuronal damage, cyclooxygenase-2 activation, endothelial dysfunction, altered Na(+)/K(+)-ATPase pump function, impaired C-peptide-related signaling pathways, endoplasmic reticulum stress, and low-grade inflammation. This review summarizes current evidence regarding the role of low-grade inflammation as a potential therapeutic target for DNs.

Increased Mortality in Diabetic Foot Ulcer Patients: The Significance of Ulcer Type

Diabetic foot ulcer (DFU) patients have a greater than twofold increase in mortality compared with nonulcerated diabetic patients. We investigated (a) cause of death in DFU patients, (b) age at death, and (c) relationship between cause of death and ulcer type. This was an eleven-year retrospective study on DFU patients who attended King's College Hospital Foot Clinic and subsequently died. A control group of nonulcerated diabetic patients was matched for age and type of diabetes mellitus. The cause of death was identified from death certificates (DC) and postmortem (PM) examinations. There were 243 DFU patient deaths during this period. Ischaemic heart disease (IHD) was the major cause of death in 62.5% on PM compared to 45.7% on DC. Mean age at death from IHD on PM was 5 years lower in DFU patients compared to controls (68.2 ± 8.7 years versus 73.1 ± 8.0 years, P = 0.015). IHD as a cause of death at PM was significantly linked to neuropathic foot ulcers (OR 3.064, 95% CI 1.003-9.366, and P = 0.049). Conclusions. IHD is the major cause of premature mortality in DFU patients with the neuropathic foot ulcer patients being at a greater risk.

Quality of life in polyneuropathy: association with biomarkers of small fiber impairment

Background

Polyneuropathy presumably lowers quality of life (QoL). However, there is a lack of systematic studies that assess QoL changes and biomarkers of polyneuropathy as determinants of QoL. We aimed to investigate the relationship between every specific aspect of QoL and the clinical parameters used to assess the impairment of motor, sensory (large and small fibers), and autonomic nerves in polyneuropathy.

Methods

Polyneuropathy patients were recruited from September 2013 to March 2014; QoL was assessed using (1) the WHO Quality of Life-BREF (WHOQoL), (2) the European Quality of Life-5 Dimensions, and (3) the Brief Pain Inventory Short Form. Neuropathy examinations included nerve conduction studies, autonomic function tests, quantitative sensory testing (QST), and intraepidermal nerve fiber (IENF) density assessment of skin biopsies.

Results

There were 61 polyneuropathy patients (male/female = 38/23, mean age 58.14 ± 12.95 years). Patients had a lower QoL than age-and gender-matched controls in the physical and psychological domains of the WHOQoL. Among the biomarkers for different nerve fiber categories, only the small fiber neuropathy assessments were significantly related to all domains of the WHOQoL. In contrast, the parameters of the large fiber neuropathy were independent of QoL. Patients with abnormal temperature thresholds and a lower IENF density had lower WHOQoL scores compared to patients with normal thresholds and IENF densities. Warm threshold of the foot in QST was linearly correlated with all domains of the WHOQoL.

Conclusions

QoL scores were reduced in polyneuropathy, and biomarkers of small fiber neuropathy, i.e., warm threshold and IENF density were discriminating predictors of QoL.

Electronic supplementary material

The online version of this article (doi:10.1186/s12955-015-0363-9) contains supplementary material, which is available to authorized users.

Increased aortic stiffness predicts future development and progression of peripheral neuropathy in patients with type 2 diabetes: the Rio de Janeiro Type 2 Diabetes Cohort Study

AIMS/HYPOTHESIS

Diabetic peripheral neuropathy (DPN) is a chronic microvascular complication that is strongly associated with poor glycaemic control and also with a worse prognosis. We aimed to evaluate the predictors of the development and progression of DPN in a cohort of high-risk patients with type 2 diabetes.

METHODS

In a prospective study, 477 patients with type 2 diabetes were clinically assessed for the presence of DPN at baseline and after a median follow-up of 6.2 years (range 2-10 years). Clinical laboratory data were obtained at study entry and throughout the follow-up. Aortic stiffness was assessed by the carotid-femoral pulse wave velocity (cf-PWV) at baseline. Multivariate Poisson regression analysis was used to examine independent predictors of the development/progression of DPN.

RESULTS

At baseline, 135 patients (28%) had DPN, and during follow-up 97 patients (20%) had either a new development or a worsening of DPN. Patients who showed a development or progression of DPN were taller and had a longer duration of diabetes, a greater prevalence of other microvascular complications and hypertension, greater aortic stiffness and poorer glycaemic control than patients who did not have new or progressive neuropathy. After adjustments for the baseline prevalence of DPN, the patient's age and sex, and the time interval between DPN assessments; an increased aortic stiffness (cf-PWV >10 m/s) were predictive of new/progressive DPN (incidence rate ratio 2.04, 95% CI 1.28, 3.23; p = 0.002). Other independent predictors were the mean first-year HbA1c level (p = 0.05), nephropathy (p = 0.006), arterial hypertension (p = 0.06) and height (p = 0.03).

CONCLUSIONS/INTERPRETATION

Increased aortic stiffness at baseline predicts the future development or progression of peripheral neuropathy, independent of diabetic metabolic control, suggesting a physiopathological link between macrovascular and microvascular abnormalities in type 2 diabetes.

Functional disability and nursing resource use are predictive of antimicrobial resistance in nursing homes

OBJECTIVES

To use a simple measure of activities of daily living, wounds, and indwelling devices (urinary catheter, feeding tube) to predict prevalent, new, and intermittent multidrug-resistant organism (MDRO) acquisition in nursing home (NH) residents.

DESIGN

Secondary analysis, prospective cohort study.

SETTING

Southeast Michigan NHs (n = 15).

PARTICIPANTS

NH residents (N = 111, mean age 81) with two or more monthly visits (729 total).

MEASUREMENTS

Monthly microbiological surveillance for MDROs from multiple anatomic sites from enrollment until discharge or 1 year. The Arling scale, previously developed as a measure of NH residents' need (time-intensity) for nursing resources, was used to predict prevalent and time to new or intermittent acquisition (months) of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), and antibiotic-resistant gram-negative bacteria (R-GNB) colonization using multiple-failure accelerated time-factor survival analysis, controlling for comorbidity, hospitalization, and antibiotic use in the prior month.

RESULTS

One-fifth of participants had a wound, and one-third had a device. There were 60 acquisitions of MRSA, 56 of R-GNB, and 15 of VRE. Expected time to acquisition was less than 1 year for MRSA (median 6.7 months) and R-GNB (median 4.5 months) and more than 1 year for VRE (median 40 months). Arling score was associated with earlier new MRSA and VRE acquisition. A resident with only mild functional impairment and no device or wound would be expected to acquire MRSA in 20 months, versus 5 months for someone needing the most-intense nursing contact.

CONCLUSION

MDRO acquisition is common in community NHs. Need for nursing care predicts new MDRO acquisition in NHs, suggesting potential mechanisms for MDRO acquisition and strategies for future interventions for high-risk individuals (e.g., enhanced barrier precautions).

Efficacy of α-lipoic acid in diabetic neuropathy

INTRODUCTION

Neuropathy is a serious complication of diabetes. Its management focuses on glycaemic control, multifactorial cardiovascular risk intervention, pathogenesis-oriented therapy, and analgesics where needed.

AREAS COVERED

The objective of this review is assessment of efficacy and safety of α lipoic acid (ALA, also thioctic acid) in pathogenesis-oriented treatment of diabetic neuropathy. The mechanisms of action of ALA in experimental diabetic neuropathy include reduction of oxidative stress along with improvement in nerve blood flow, nerve conduction velocity, and several other measures of nerve function. There is ample evidence from randomised, double-blind, placebo-controlled clinical trials and meta-analyses, suggesting that ALA is efficacious and safe for the diabetic neuropathy, accomplishing clinically meaningful improvements.

EXPERT OPINION

ALA is a valuable therapeutic option for diabetic neuropathy. When compared with currently licensed analgesic drugs, it is better tolerated, has a more rapid onset of action, and improves paraesthesiae, numbness, sensory deficits, and muscle strength in addition to neuropathic pain. In clinical practice, ALA may be chosen in patients with early neuropathic deficits and symptoms, in whom clinical improvement is more likely. ALA should also be considered when comorbidities render other analgesics less appropriate or in the presence of cardiovascular autonomic neuropathy.

Peripheral neuropathy and the risk of cardiovascular events in type 2 diabetes mellitus

AIMS

Identifying individuals with diabetes at high risk of cardiovascular disease (CVD) remains challenging. We aimed to establish whether peripheral neuropathy (PN) is associated with incident CVD events and to what extent information on PN may improve risk prediction among individuals with type 2 diabetes.

METHODS

We obtained data for individuals with type 2 diabetes, and free of CVD, from a large primary care patient cohort. Incident CVD events were recorded during a 30-month follow-up period. Eligible individuals had complete ascertainment of cardiovascular risk factors and PN status at baseline. The association between PN and incident CVD events (non-fatal myocardial infarction, coronary revascularisation, congestive cardiac failure, transient ischaemic attack and stroke) was evaluated using Cox regression, adjusted for standard CVD risk factors. We assessed the predictive accuracy of models including conventional CVD risk factors with and without information on PN.

RESULTS

Among 13 043 eligible individuals, we recorded 407 deaths from any cause and 399 non-fatal CVD events. After adjustment for age, sex, ethnicity, systolic blood pressure, cholesterol, body mass index, HbA1c, smoking status and use of statin or antihypertensive medication, PN was associated with incident CVD events (HR 1.33; 95% CI 1.02 to 1.75, p=0.04). The addition of information on PN to a model based on standard CVD risk factors resulted in modest improvements in discrimination for CVD risk prediction and reclassified 6.9% of individuals into different risk categories.

CONCLUSIONS

PN is associated with increased risk for a first cardiovascular event among individuals with diabetes.

Recent advances in the management of diabetic distal symmetrical polyneuropathy

There is now little doubt that poor blood glucose control is an important risk factor for the development of diabetic peripheral neuropathy (DPN). Furthermore, traditional cardiovascular risk factors for macrovascular disease appear to be associated with an increased risk of DPN. The recently established International Expert Group on Diabetic Neuropathy has recommended new criteria for the diagnosis of DPN in the context of clinical and research settings. Studies in experimental diabetes examining the pathogenesis of DPN have identified a number of metabolic abnormalities including polyol pathway hyperactivity, increased advanced glycation end‐point formation, alterations in the protein kinase C beta pathway through diacylglycerol and oxidative stress. There is now strong evidence implicating nerve ischemia as the cause of DPN. Studies in human and animal models have shown reduced nerve perfusion and endoneurial hypoxia. These endoneurial microvascular changes strongly correlate with clinical severity and the degree of nerve‐fiber pathology. Unfortunately, many compounds that have been effective in animal models of neuropathy have not been successful in human diabetic neuropathy. The only compounds found to be efficacious in human diabetic neuropathy, and are in clinical use, are the anti‐oxidant, α‐lipoic acid and the aldose reductase inhibitor, epalrestat. Overall, the evidence emphasizes the importance of vascular dysfunction, driven by metabolic change, in the etiology of DPN, and highlights potential therapeutic approaches. Epidemiological data on diabetic painful neuropathic pain (DPNP) are limited. In one population‐based study, the prevalence of DPNP, as assessed by a structured questionnaire and examination, was estimated at 16%. It was notable that, of these patients, 12.5% had never reported symptoms to their doctor and 39% had never received treatment for their pain. Thus, despite being common, DPNP continues to be underdiagnosed and undertreated. Pharmacological treatment of DPNP include tricyclic compounds, serotonin noradrenalin reuptake inhibitors, the anti‐oxidant α‐lipoic acid, anticonvulsants, opiates, membrane stabilizers, topical capsaicin and so on. Management of the patient with DPNP must be tailored to individual requirements and will depend on the presence of other comorbidities. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2010.00083.x)

Relationship between fasting and 2-hour postprandial plasma glucose levels and vascular complications in patients with type 2 diabetes mellitus

OBJECTIVE

To investigate the relationship between fasting and 2-h postprandial plasma glucose concentrations and vascular complications in type 2 diabetes.

METHODS

Consecutive patients with type 2 diabetes admitted for blood glucose control were grouped according to their fasting and 2-h postprandial plasma glucose levels. Frequency and severity of diabetic retinopathy and nephropathy, number of carotid artery plaques, coefficient of variation of R-R intervals (CVRR), brachial-ankle pulse wave velocity (baPWV), intima-media thickness, brain natriuretic peptide level, ankle-brachial index, and high-sensitivity C-reactive protein levels were compared.

RESULTS

In the 206 patients studied, mean±SD age, glycosylated haemoglobin and duration of diabetes were 63.4±13.7 years, 9.8±1.8% and 13.4±8.9 years, respectively. Patients with high fasting plasma glucose levels had a higher frequency of proliferative retinopathy than those with low fasting levels. Patients with medium or high 2-h postprandial plasma glucose levels had higher baPWV and lower CVRR, respectively, than those with low 2-h levels. There was an inverse correlation between baPWV and CVRR.

CONCLUSION

Elevated fasting and postprandial plasma glucose levels are risk factors for vascular complications in type 2 diabetes mellitus.

Heart rate variability

Heart rate variability (HRV) provides indirect insight into autonomic nervous system tone, and has a well-established role as a marker of cardiovascular risk. Recent decades brought an increasing interest in HRV assessment as a diagnostic tool in detection of autonomic impairment, and prediction of prognosis in several neurological disorders. Both bedside analysis of simple markers of HRV, as well as more sophisticated HRV analyses including time, frequency domain and nonlinear analysis have been proven to detect early autonomic involvement in several neurological disorders. Furthermore, altered HRV parameters were shown to be related with cardiovascular risk, including sudden cardiac risk, in patients with neurological diseases. This chapter aims to review clinical and prognostic application of HRV analysis in diabetes, stroke, multiple sclerosis, muscular dystrophies, Parkinson's disease and epilepsy.

Long-term prognosis of diabetic foot patients and their limbs: amputation and death over the course of a decade

OBJECTIVE

There is a dearth of long-term data regarding patient and limb survival in patients with diabetic foot ulcers (DFUs). The purpose of our study was therefore to prospectively investigate the limb and person survival of DFU patients during a follow-up period of more than 10 years.

RESEARCH DESIGN AND METHODS

Two hundred forty-seven patients with DFUs and without previous major amputation consecutively presenting to a single diabetes center between June 1998 and December 1999 were included in this study and followed up until May 2011. Mean patient age was 68.8 ± 10.9 years, 58.7% were male, and 55.5% had peripheral arterial disease (PAD). Times to first major amputation and to death were analyzed with Kaplan-Meier curves and Cox multiple regression.

RESULTS

A first major amputation occurred in 38 patients (15.4%) during follow-up. All but one of these patients had evidence of PAD at inclusion in the study, and 51.4% had severe PAD [ankle-brachial pressure index ≤0.4]). Age (hazard ratio [HR] per year, 1.05 [95% CI, 1.01-1.10]), being on dialysis (3.51 [1.02-12.07]), and PAD (35.34 [4.81-259.79]) were significant predictors for first major amputation. Cumulative mortalities at years 1, 3, 5, and 10 were 15.4, 33.1, 45.8, and 70.4%, respectively. Significant predictors for death were age (HR per year, 1.08 [95% CI, 1.06-1.10]), male sex ([1.18-2.32]), chronic renal insufficiency (1.83 [1.25-2.66]), dialysis (6.43 [3.14-13.16]), and PAD (1.44 [1.05-1.98]).

CONCLUSIONS

Although long-term limb salvage in this modern series of diabetic foot patients is favorable, long-term survival remains poor, especially among patients with PAD or renal insufficiency.

Evaluation of oxidative stress markers in pathogenesis of diabetic neuropathy

Experimental evidences suggest that hyperglycaemia-induced overproduction of reactive oxygen species and subsequent damage to proteins, lipids and DNA may play a key role in the development of distal symmetric polyneuropathy (DSPN)—the most common complication of diabetes mellitus. The study population consisted of 51 individuals aged 52–82 years classified into 3 groups: 16 patients diagnosed with type 2 diabetes mellitus (T2DM) with DSPN, 16 T2DM patients without DSPN and 19 control subjects without diabetes and neuropathy. The study was conducted to determine the activity of antioxidant enzymes: catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPX) and total antioxidant status (TAS) in the examined groups. An alkaline comet assay was used to determine the extent of DNA damage of oxidized purines as glicosylo-formamidoglicosylase (Fpg) sites, and oxidized pyrimidines as endonuclease III (Nth) sites. A significant decrease of SOD (P < 0.05), GPX (P < 0.05) and nonsignificant decrease of CAT (P > 0.05), and TAS status (P > 0.05) were seen in T2DM patients with neuropathy compared to T2DM patients as well as controls. T2DM patients with or without neuropathy revealed significantly lower (P < 0.05) plasma concentration of nitrous oxide compared to the control subjects. Endogenous level of oxidative DNA damage in T2DM patients with DSPN was significantly higher compared both to the controls and T2DM patients without DSPN (P < 0.001). Moreover, lymphocytes isolated from T2DM patients with DSPN were more susceptible to oxidative DNA lesions induced by hydrogen peroxide than from T2DM patients without DSPN (P < 0.001). Our results confirm hypothesis that oxidative stress may play a substantial role in the development and progression of diabetic distal symmetric polyneuropathy.

Advances in the epidemiology, pathogenesis and management of diabetic peripheral neuropathy

Diabetic peripheral neuropathy (DPN) affects up to 50% of patients with diabetes and is a major cause of morbidity and increased mortality. Its clinical manifestations include painful neuropathic symptoms and insensitivity, which increases the risk for burns, injuries and foot ulceration. Several recent studies have implicated poor glycaemic control, duration of diabetes, hyperlipidaemia (particularly hypertryglyceridaemia), elevated albumin excretion rates and obesity as risk factors for the development of DPN. Although there is now strong evidence for the importance of nerve microvascular disease in the pathogenesis of DPN, the risk factors for painful DPN are not known. However, emerging evidence regarding the central correlates of painful DPN is now afforded by brain imaging. The diagnosis of DPN begins with a careful history of sensory and motor symptoms. The quality and severity of neuropathic pain if present should be assessed using a suitable scale. Clinical examination should include inspection of the feet and evaluation of reflexes and sensory responses to vibration, light touch, pinprick and the 10-g monofilament. Glycaemic control and addressing cardiovascular risk is now considered important in the overall management of the neuropathic patient. Pharmacological treatment of painful DPN includes tricyclic compounds, serotonin-norepinephrine reuptake inhibitors (e.g. duloxetine), anticonvulsants (e.g. pregabalin), opiates, membrane stabilizers, the antioxidant alpha lipoic acid and others. Over the past 7 years, new agents with perhaps less side effect profiles have immerged. Management of patients with painful neuropathy must be tailored to individual requirements and will depend on the presence of other co-morbidities. There is limited literature with regard to combination treatment.

Critical appraisal of the use of alpha lipoic acid (thioctic acid) in the treatment of symptomatic diabetic polyneuropathy

BACKGROUND

The most common of the neuropathies associated with diabetes mellitus, diabetic sensorimotor polyneuropathy (DSPN) is a syndrome of diffuse, length-dependent, symmetric nerve dysfunction. The condition is linked with substantial morbidity, frequent healthcare utilization, and compromised quality of life due to related discomfort. Correspondingly, antidepressants, anticonvulsants, and opioids are regularly prescribed with the goal of pain control. However, the agents rarely provide complete pain relief and fail to address progression of the disorder. Whereas strict blood glucose control can slow the onset and worsening of DSPN, near-normoglycemia is not easily attainable. Evidence implicating oxidative processes in the pathogenesis of DSPN offers one potentially important therapeutic avenue. Due to its properties as a potent antioxidant, alpha lipoic acid (ALA) could mitigate the development of DSPN and attenuate resultant symptoms and signs. Approved for treatment of DSPN in Germany, the agent is not more widely used due to uncertainty about its efficacy and reported adverse effects. Here we review the effectiveness and tolerability of ALA in the treatment of symptomatic DSPN.

METHODS

The MEDLINE, EMBASE, and Cochrane Library databases were searched for English-language literature on the topic. Randomized, blinded studies comparing parenteral and oral ALA with placebo in the treatment of peripheral neuropathy in diabetic adults were selected. Analysis included studies with a level of evidence of at least 2b.

RESULTS

The current appraisal summarizes data from 1160 participants in the ALADIN, SYDNEY, ORPIL, SYDNEY 2, and ALADIN III trials. In four of the studies, ALA provided significant improvement in manifestations of DSPN.

CONCLUSION

Treatment with ALA 600 mg iv daily for 3 weeks represents a well-tolerated and effective therapy for DSPN. An oral dose of 600 mg daily administered for up to 5 weeks could offer benefits in symptoms and signs of DSPN without significant side effects.

Association between Diabetic Polyneuropathy and Cardiovascular Complications in Type 2 Diabetic Patients

BACKGROUND

Diabetes mellitus is a major independent risk factor for cardiovascular disease (CVD), but high cardiovascular risk in diabetes mellitus patients is not completely explained by clustering traditional risk factors. Recently, associations between diabetic polyneuropathy (DPN) and macrovasculopathy have been suggested. We aimed to assess associations between DPN and cardiovascular complications in type 2 diabetic patients.

METHODS

Microvascular and cardiovascular complications were evaluated in 1,041 type 2 diabetic patients.

RESULTS

In patients with DPN, the age, prevalence of hypertension, diabetes duration, systolic blood pressure, pulse pressure, and hemoglobin glycation (HbA1c) levels were significantly higher, while the high density lipoprotein cholesterol (HDL-C) levels were lower than in those without DPN. The prevalence of CVD was higher in patients with DPN. In multivariate analysis, DPN was independently associated with CVD (odds ratio, 1.801; 95% confidence interval, 1.009 to 3.214).

CONCLUSION

Our results showed that DPN was associated with a high prevalence of cardiovascular disease in type 2 diabetic patients, but further studies are needed to investigate the causative nature of associations between DPN and CVD.

Effects of cardiac autonomic dysfunction on mortality risk in the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial

OBJECTIVE

Intensive therapy targeting normal blood glucose increased mortality compared with standard treatment in a randomized clinical trial of 10,251 participants with type 2 diabetes at high-risk for cardiovascular disease (CVD) events. We evaluated whether the presence of cardiac autonomic neuropathy (CAN) at baseline modified the effect of intensive compared with standard glycemia treatment on mortality outcomes in the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial participants.

RESEARCH DESIGN AND METHODS

CAN was assessed by measures of heart rate variability (HRV) and QT index (QTI) computed from 10-s resting electrocardiograms in 8,135 ACCORD trial participants with valid measurements (mean age 63.0 years, 40% women). Prespecified CAN definitions included a composite of the lowest quartile of HRV and highest QTI quartile in the presence or absence of peripheral neuropathy. Outcomes were all-cause and CVD mortality. Associations between CAN and mortality were evaluated by proportional hazards analysis, adjusting for treatment group allocation, CVD history, and multiple prespecified baseline covariates.

RESULTS

During a mean 3.5 years follow-up, there were 329 deaths from all causes. In fully adjusted analyses, participants with baseline CAN were 1.55-2.14 times as likely to die as participants without CAN, depending on the CAN definition used (P < 0.02 for all). The effect of allocation to the intensive group on all-cause and CVD mortality was similar in participants with or without CAN at baseline (P(interaction) > 0.7).

CONCLUSIONS

Whereas CAN was associated with increased mortality in this high-risk type 2 diabetes cohort, these analyses indicate that participants with CAN at baseline had similar mortality outcomes from intensive compared with standard glycemia treatment in the ACCORD cohort.

Mortality associated with acute Charcot foot and neuropathic foot ulceration

OBJECTIVE

To compare the mortality of patients with an acute Charcot foot with a matched population with uninfected neuropathic foot ulcers (NFUs).

RESEARCH DESIGN AND METHODS

Data were extracted from a specialist departmental database, supplemented by hospital records. The findings were compared with the results of earlier populations with Charcot foot and uninfected NFUs managed from 1980. Finally, the results of all patients with acute Charcot foot and all control subjects managed between 1980 and 2007 were compared with normative mortality data for the U.K. population.

RESULTS

A total of 70 patients presented with an acute Charcot foot (mean age 57.4 +/- 12.0 years; 48 male [68.6%]) between 2001 and 2007; there were 66 matched control subjects. By 1 October 2008, 13 (eight male; 18.6%) patients with a Charcot foot had died, after a median of 2.1 years (interquartile range 1.1-3.3). Twenty-two (20 male; 33.3%) control subjects had also died after a median of 1.3 years (0.6-2.5). There was no difference in survival between the two groups (log-rank P > 0.05). Median survival of all 117 patients with acute Charcot foot managed between 1980 and 2007 was 7.88 years (4.0-15.4) and was not significantly different from the control NFU patients (8.43 years [3.4-15.8]). When compared with normative U.K. population data, life expectancy in the two groups was reduced by 14.4 and 13.9 years, respectively.

CONCLUSIONS

These data confirm that the mortality in patients presenting to our unit with either an acute Charcot foot and an uninfected neuropathic ulcer was unexpectedly high.

Effect of intensive compared with standard glycemia treatment strategies on mortality by baseline subgroup characteristics: the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial

OBJECTIVE

To determine if baseline subgroups in the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial can be identified for whom intensive compared with standard glycemia treatment had different effects on all-cause mortality.

RESEARCH DESIGN AND METHODS

Exploratory post hoc intention-to-treat comparisons were made between intensive and standard glycemia groups on all-cause mortality by subgroups defined by baseline characteristics.

RESULTS

There were few significant interactions between baseline characteristics and effects of intensive versus standard glycemia treatment on mortality: self-reported history of neuropathy (hazard ratio [HR] 1.95, 95% CI 1.41-2.69) versus no history of neuropathy (0.99, 0.79-1.26; P value for interaction 0.0008), higher A1C (A1C >8.5%: HR 1.64, 95% CI 1.22-2.22; A1C 7.5-8.4%: 1.00, 0.75-1.34; A1C <7.5%: 1.00, 0.67-1.50; P value for interaction 0.04), and aspirin use (HR 1.45, 95% CI 1.13-1.85, compared with 0.96, 0.72-1.27, in nonusers; P value for interaction 0.03).

CONCLUSIONS

We found a remarkable similarity of effect from intensive compared with standard glycemia treatment on mortality across most baseline subgroups. No differential effect was found in subgroups defined by variables anticipated to have an interaction: age, duration of diabetes, and previous history of cardiovascular disease. The three baseline characteristics that defined subgroups for which there was a differential effect on mortality may help identify patients with type 2 diabetes at higher risk of mortality from intensive regimens for glycemic control. Further research is warranted.