Prevalence of lower extremity diseases associated with normal glucose levels, impaired fasting glucose, and diabetes among U.S. adults aged 40 or older

Prevalence of painful and painless diabetic peripheral neuropathy in the Northern Danish Region: A population-based study

BACKGROUND

Diabetic peripheral neuropathy (DPN) is a common complication of diabetes, yet varying estimates of its prevalence exist. The present study aimed to estimate a questionnaire-centered prevalence of painful and painless DPN in the Northern Danish Region, examine its geographical distribution within the region, and investigate associations between DPN and potential risk factors.

METHODS

A questionnaire-based survey was sent to all persons living with diabetes in the Northern Danish Region using electronic mail. Persons with diabetes were identified using The National Health Insurance Service Registry. The survey included information on demographics, socioeconomics, municipality, diabetes type, duration, and treatment, as well as the validated questionnaires Michigan Neuropathy Screening Instrument-questionnaire (MNSIq) and the Douleur Neuropathique en 4 Questions (DN4)-interview. Possible DPN was defined as an MNSIq-score ≥ 4, while possible painful DPN was defined as pain in both feet and a DN4-interview score ≥ 3.

RESULTS

A total of 23,206 eligible people were identified as having diabetes and approximately 33 % answered all questionnaires. The prevalence of possible DPN was 23.3 % (95 % CI: 22.4-24.3 %), while the prevalence of possible painful DPN was 18.0 % (17.1-18.8 %). The prevalence of possible DPN ranged from 22.1 % to 35.0 % between municipalities, while the prevalence of possible painful DPN ranged from 15.6 % to 20.0 %. High body-mass index, long diabetes duration, insulin use, glucagon-like-peptide-1-analogue use, and low income were associated with increased risk of DPN.

CONCLUSION

The high prevalence of possible painless and painful DPN emphasizes the need for better prevention and careful screening even in high-income countries.

Correlation Between Growth Differentiation Factor-15 and Peripheral Neuropathy in Patients with Type 2 Diabetes Mellitus

Purpose

To inquire into the relationship between diabetic peripheral neuropathy (DPN) and serum levels of growth differentiation factor-15 (GDF-15) in individuals with type 2 diabetes mellitus (T2DM).

Patients and Methods

Out of 162 T2DM patients classified according to the diagnostic criteria of DPN, 75 were allocated to the non-DPN group and 87 to the DPN group. In turn, based on serum GDF-15 quartiles, all patients were additionally divided (GDF-15 low to high) into group A (40 cases), group B (41 cases), group C (41 cases), and group D (40 cases). General data and laboratory indexes of patients were collected, and enzyme-linked immunosorbent assay (ELISA) was used to determine serum GDF-15 levels.

Results

Compared to the non-DPN group, in the DPN group GDF-15 levels were noticeably greater (P < 0.001). Using serum GDF-15 as a grouping variable, DPN prevalence and body mass index were gradually increased, motor and sensory nerve latencies were gradually lengthened, and amplitude (Amp) and nerve conduction velocity (NCV) were gradually decreased with increasing GDF-15 levels (P < 0.05). Linear regression modeling revealed that GDF-15 levels correlated positively with the latencies of sensory and motor nerves, and negatively with their corresponding NCV (P < 0.05). Binary logistic regression results indicated GDF-15 as an independent predictor for DPN (P < 0.05), whereas restricted cubic spline analysis indicated a dose-response, nonlinear relationship between GDF-15 and DPN.

Conclusion

Serum GDF-15 level strongly correlates with DPN, and may represent an independent predictor and a biological marker for the disease.

Augustus Waller's foresight realized: SARM1 in peripheral neuropathies

Peripheral neuropathy is a common neurodegenerative condition characterized by numbness, tingling, pain, and weakness that frequently starts in the distal limbs. Arising from multiple etiologies, many peripheral neuropathies exhibit a slowly progressive course due to axon degeneration for which no effective treatments exist. During the past decade, numerous crucial insights into mechanisms of axon degeneration in peripheral neuropathies emerged from experiments involving nerve-cutting procedures, revealing the central role of the SARM1 axon degeneration pathway in both. Here I review commonalities and differences in the role of SARM1 after nerve cut and in several acquired and inherited peripheral neuropathies. This new knowledge now paves the way for the development of therapeutics that directly address root causes of various kinds of neuropathies.

A Phase 3, Multicenter, Randomized, Double-Blind, Placebo-Controlled 14-Week Study of Mirogabalin in Chinese Patients with Diabetic Peripheral Neuropathic Pain

INTRODUCTION

There is no approved effective drug for diabetic peripheral neuropathic pain (DPNP) in China. Gabapentinoids including mirogabalin have shown promise, although data in Chinese patients are scarce.

METHODS

This phase 3, multicenter, randomized, double-blind, placebo-controlled trial investigated the efficacy and safety of mirogabalin for treating DPNP in China. Mirogabalin was administered at 5 mg twice daily for the first week and uptitrated to 15 mg twice daily for a total duration of 14 weeks. The primary efficacy endpoint was the change from baseline in weekly average daily pain score (ADPS) at week 14; secondary endpoints included the ADPS responder rate, Short-Form McGill Pain Questionnaire visual analogue scale score, patient global impression of change (PGIC), average daily sleep interference score (ADSIS), EuroQol 5-dimensions 5-levels (EQ-5D-5L), and incidence of treatment-emergent adverse events (TEAEs).

RESULTS

Of 393 patients (mirogabalin, n = 196; placebo n = 197), the mean age was 58.2 years (mirogabalin, 58.7 years; placebo, 57.7 years) and 54.2% were male (mirogabalin, 56.1%; placebo, 52.3%). Mirogabalin elicited a greater change from baseline in the weekly ADPS vs. placebo at week 14: least-squares mean difference (95% confidence interval) vs. placebo - 0.39 (- 0.74, - 0.04), p = 0.0301. PGIC, ADSIS, and EQ-5D-5L data reflected significantly better improvements for patients receiving mirogabalin vs. placebo. The incidence of TEAEs was 75.0% and 75.1% in the mirogabalin and placebo groups, respectively. Most TEAEs were mild or moderate, and the incidence of TEAEs leading to treatment discontinuation was 2.6% in the mirogabalin group and 1.5% in the placebo group.

CONCLUSIONS

Although the effect size of mirogabalin was reduced due to the placebo effect, mirogabalin is a safe and effective treatment option for Chinese patients with DPNP.

TRIAL REGISTRATION

ClinicalTrials.gov identifier, NCT04094662.

Surgical Management of Complex Ankle Fractures in Patients with Diabetes: A National Retrospective Multicentre Study

Objectives: Patients with ankle fractures associated with diabetes experience more complications following standard open reduction-internal fixation (ORIF) than those without diabetes. Augmented fixation strategies, namely extended ORIF and hindfoot nails (HFNs), may offer better results and early weightbearing in this group. The aim of this study was to define the population of patients with diabetes undergoing primary fixation for ankle fractures. Secondarily, we aimed to assess the utilisation of standard and augmented strategies and the effect of these choices on surgical outcomes, including early post-operative weightbearing and surgical complications. Methods: A national multicentre retrospective cohort study was conducted between January and June 2019 in 56 centres (10 major trauma centres and 46 trauma units) in the United Kingdom; 1360 patients with specifically defined complex ankle fractures were enrolled. The patients' demographics, fixation choices and surgical and functional outcomes were recorded. Statistical analysis was performed to compare high-risk patients with and without diabetes. Results: There were 316 patients in the diabetes cohort with a mean age of 63.9 yrs (vs. 49.3 yrs. in the non-diabetes cohort), and a greater frailty score > 4 (24% vs. 14% (non-diabetes cohort) (p < 0.03)); 7.5% had documented neuropathy. In the diabetes cohort, 79.7% underwent standard ORIF, 7.1% extended ORIF and 10.2% an HFN, compared to 87.7%, 3.0% and 10.3% in the non-diabetes cohort. Surgical wound complications after standard-ORIF were higher in the diabetes cohort (15.1% vs. 8.7%) (p < 0.02), but patients with diabetes who underwent augmented techniques showed little difference in surgical outcomes/complications compared to non-diabetes patients, even though early-weightbearing rates were greater than for standard-ORIF. Conclusions: Ankle fractures in diabetes occur in older, frailer patients, whilst lower-than-expected neuropathy rates suggest a need for improved assessment. Augmented surgical techniques may allow earlier weightbearing without increasing complications, in keeping with modern guidelines in ankle fracture management.

Peripheral Neuropathy

Peripheral neuropathy is a commonly encountered diagnosis in both neurology and primary care office settings. It is important for primary care providers to identify, characterize, and diagnose patients with neuropathy. This study aims to describe the clinical presentation, diagnostic work up, and treatment options for this entity, as well as the identification of atypical features that should prompt specialized laboratory testing, electrodiagnostic testing, and neurologic consultation.

Prevalence of Distal Symmetrical Polyneuropathy by Diabetes Prevention Program Treatment Group, Diabetes Status, Duration of Diabetes, and Cumulative Glycemic Exposure

OBJECTIVE

To assess associations between distal symmetric polyneuropathy (DSPN) and Diabetes Prevention Program (DPP) treatment groups, diabetes status or duration, and cumulative glycemic exposure approximately 21 years after DPP randomization.

RESEARCH DESIGN AND METHODS

In the DPP, 3,234 adults ≥25 years old at high risk for diabetes were randomized to an intensive lifestyle (ILS), metformin, or placebo intervention to prevent diabetes. After the DPP ended, 2,779 joined the Diabetes Prevention Program Outcomes Study (DPPOS). Open-label metformin was continued, placebo was discontinued, ILS was provided in the form of semiannual group-based classes, and all participants were offered quarterly lifestyle classes. Symptoms and signs of DSPN were assessed in 1,792 participants at DPPOS year 17. Multivariable logistic regression models were used to evaluate DSPN associations with treatment group, diabetes status/duration, and cumulative glycemic exposure.

RESULTS

At 21 years after DPP randomization, 66% of subjects had diabetes. DSPN prevalence did not differ by initial DPP treatment assignment (ILS 21.5%, metformin 21.5%, and placebo 21.9%). There was a significant interaction between treatment assignment to ILS and age (P < 0.05) on DSPN. At DPPOS year 17, the odds ratio for DSPN in comparison with ILS with placebo was 17.4% (95% CI 3.0, 29.3) lower with increasing 5-year age intervals. DSPN prevalence was slightly lower for those at risk for diabetes (19.6%) versus those with diabetes (22.7%) and was associated with longer diabetes duration and time-weighted HbA1c (P values <0.001).

CONCLUSIONS

The likelihood of DSPN was similar across DPP treatment groups but higher for those with diabetes, longer diabetes duration, and higher cumulative glycemic exposure. ILS may have long-term benefits on DSPN for older adults.

The effect of cocaine on patients undergoing total hip arthroplasty

Background

Cocaine use has surged in the past decade, with 4.8 million Americans (1.7% of the population greater than 12) reporting use in 2021, leading to a healthcare burden of 1.3 billion dollars. Cocaine users experience prolonged hospital stays, higher costs, worse surgical outcomes, increased risk of medical conditions, and inflammation-related osteoarthritis. The study aims to identify factors influencing length of stay, costs, and perioperative complications in cocaine users undergoing total hip arthroplasty (THA) to reduce these risks.

Methods

This study utilized the NIS database, providing comprehensive information on patient demographics, length of stay, hospital costs, and complications. Statistical analyses were conducted using SPSS software, including propensity matching and significance testing, to compare outcomes between cocaine users (CU) and non-cocaine users (NCU) undergoing total hip arthroplasty.

Results

After propensity matching, cocaine users had a significantly longer LOS (4.8 days) in comparison to non-cocaine users (2.6 days) (p < 0.001). Similarly, the CU group had a larger of care (87984.9) than the NCU group (69149.2) (p < 0.001). Cocaine users had significantly higher rates of blood loss anemia (OR: 3.24, 95% CI: 2.21, 4.73), blood loss anemia (OR: 1.59, 95% CI: 1.12, 2.24), blood transfusion (OR: 2.23, 95% CI: 1.04, 4.78), periprosthetic dislocation (OR: 6.57, 95% CI: 1.47, 29.32), and periprosthetic infection (OR: 4.59, 95% CI: 1.54, 13.68) than patients in the non-cocaine user's group.

Conclusion

Cocaine users had a significantly longer length of stay, higher costs of care, and an increased number of post-operative complications compared to non-cocaine users. These data contribute to understanding the potential ramifications of cocaine users undergoing THA.

Association of reproductive factors and exogenous hormone use with distal sensory polyneuropathy among postmenopausal women in the United States: results from 1999 to 2004 NHANES

Postmenopausal status is a risk factor for distal sensory polyneuropathy-the most common type of peripheral neuropathy. We aimed to investigate associations between reproductive factors and history of exogenous hormone use with distal sensory polyneuropathy among postmenopausal women in the United States using data from the National Health and Nutrition Examination Survey 1999-2004, and to explore the modifying effects of ethnicity on these associations. We conducted a cross-sectional study among postmenopausal women aged ≥ 40 years. Women with a history of diabetes, stroke, cancer, cardiovascular disease, thyroid disease, liver disease, weak or failing kidneys, or amputation were excluded. Distal sensory polyneuropathy was measured using a 10-g monofilament test, and a questionnaire was used to collect data on reproductive history. Multivariable survey logistic regression was used to test the association between reproductive history variables and distal sensory polyneuropathy. In total, 1144 postmenopausal women aged ≥ 40 years were included. The adjusted odds ratios were 8.13 [95% confidence interval (CI) 1.24-53.28] and 3.18 (95% CI 1.32-7.68) for age at menarche < 11 years and time since menopause > 20 years, respectively, which were positively associated with distal sensory polyneuropathy; adjusted odds ratios were 0.45 for the history of breastfeeding (95% CI 0.21-0.99) and 0.41 for exogenous hormone use (95% CI 0.19-0.87) were negatively associated. Subgroup analysis revealed ethnicity-based heterogeneity in these associations. Age at menarche, time since menopause, breastfeeding, and exogenous hormone use were associated with distal sensory polyneuropathy. Ethnicity significantly modified these associations.

The Association of Inflammatory Factors With Peripheral Neuropathy: The Study of Women's Health Across the Nation

PURPOSE

Previous work has focused on the role of diabetes in peripheral neuropathy (PN), but PN often occurs before, and independently from, diabetes. This study measures the association of cardiometabolic and inflammatory factor with PN, independent of diabetes.

METHODS

Study of Women's Health Across the Nation participants (n = 1910), ages 60 to 73 (mean 65.6) were assessed for PN by symptom questionnaire and monofilament testing at the 15th follow-up visit (V15). Anthropometric measures and biomarkers were measured at study baseline approximately 20 years prior, and C-reactive protein (CRP) and fibrinogen were measured longitudinally. Log-binomial regression was used to model the association between metabolic syndrome (MetS), obesity (≥35 body mass index), CRP, and fibrinogen with PN, adjusting for sociodemographic and health behavior measures.

RESULTS

Baseline MetS [prevalence ratio (PR) 1.79, 95% CI (1.45, 2.20)], obesity [PR 2.08 (1.65, 2.61)], median CRP [PR 1.32 per log(mg/dL), (1.20, 1.45)], and mean fibrinogen (PR 1.28 per 100 mg/dL, (1.09, 1.50)] were associated with PN symptoms at V15. After excluding participants with baseline diabetes or obesity, MetS [PR 1.59 (1.17, 2.14)] and CRP [PR 1.19 per log(mg/dL), (1.06, 1.35)] remained statistically significantly associated with PN. There was a negative interaction between MetS and obesity, and the association between these conditions and PN was mediated by CRP.

CONCLUSIONS

Cardiometabolic factors and inflammation are significantly associated with PN, independent of diabetes and obesity. CRP mediates the relationship of both obesity and MetS with PN, suggesting an etiological role of inflammation in PN in this sample.

Peripheral Neuropathy and Vision and Hearing Impairment in US Adults With and Without Diabetes

We aimed to assess the associations of peripheral neuropathy (PN) with vision and hearing impairment among adults aged ≥40 years who attended the lower-extremity disease exam for the National Health and Nutrition Examination Survey (United States, 1999-2004). Overall, 11.8% (standard error (SE), 0.5) of adults had diabetes, 13.2% (SE, 0.5) had PN (26.6% (SE, 1.4) with diabetes, 11.4% (SE, 0.5) without diabetes), 1.6% (SE, 0.1) had vision impairment, and 15.4% (SE, 1.1) had hearing impairment. The prevalence of vision impairment was 3.89% (95% CI: 2.99, 5.05) among adults with PN and 1.29% (95% CI: 1.04, 1.60) among adults without PN (P < 0.001). After adjustment, PN was associated with vision impairment overall (odds ratio (OR) = 1.48, 95% confidence interval (CI): 1.03, 2.13) and among adults without diabetes (OR = 1.80, 95% CI: 1.17, 2.77) but not among adults with diabetes (P for interaction = 0.018). The prevalence of hearing impairment was 26.5% (95% CI: 20.4, 33.7) among adults with PN and 14.2% (95% CI: 12.4, 16.3) among adults without PN (P < 0.001). The association of PN with moderate/severe hearing impairment was significant overall (OR = 2.55, 95% CI: 1.40, 4.64) and among adults without diabetes (OR = 3.26, 95% CI: 1.80, 5.91). Overall, these findings suggest an association between peripheral and audiovisual sensory impairment that is unrelated to diabetes.

The efficacy of PDE5 inhibitors in diabetic patients

BACKGROUND

Phosphodiesterase 5 inhibitors (PDE5i), since their introduction in the late 1990s, have proven their efficacy in treating several conditions, predominantly pulmonary hypertension and erectile dysfunction where they remain the first-line therapeutic option. However, in the recent years, growing evidence from both animal and human studies has emerged to suggest the additional benefits of PDE5i in cardiovascular and metabolic disorders. This is of specific interest to the diabetes population where prevalent cardiovascular disease and metabolic dysregulation significantly contribute to the increased morbidity and mortality.

OBJECTIVES

To examine the available data on the non-standard, pleiotropic effects of PDE5i in patients with diabetes mellitus.

MATERIALS AND METHODS

The review of the published background research, preclinical studies and clinical trials.

RESULTS

In human studies, PDE5 inhibition appeared to be associated with reduced cardiovascular mortality and overall improved clinical outcomes in those with established cardiovascular disease. PDE5i were also consistently found to reduce albuminuria in subjects with diabetic nephropathy. Furthermore, animal data suggest a plausible effect of this group of medication on sensory function and neuropathic symptoms in diabetic neuropathy as well as improved wound healing. A decrease in insulin resistance and augmentation of beta cell function seen in preclinical studies has not been consistently demonstrated in human trials.

DISCUSSION AND CONCLUSION

In animal models, PDE5 inhibition appears to decrease oxidative stress and reduce some of the micro- and macrovascular complications associated with diabetes. However, data from human trials are limited and largely inconsistent, highlighting the need for adequately powered, randomised-controlled trials in diabetic cohorts in order to fully assess the benefits of PDE5i in this group of patients.

Nerve conduction velocity is independently associated with bone mineral density in type 2 diabetes mellitus

AIM

This study investigated the association between nerve conduction velocity (NCV) and bone mineral density (BMD) in patients with type 2 diabetes mellitus (T2DM).

METHODS

This study retrospectively collected medical data of T2DM patients who underwent dual-energy X-ray absorptiometry and nerve conduction study at the Shanghai Ruijin Hospital, Shanghai, China. The primary outcome was the total hip BMD T-score. The main independent variables were motor nerve conduction velocities (MCVs), sensory nerve conduction velocities (SCVs), and composite Z-scores of MCV and SCV. T2DM patients were divided into total hip BMD T-scores < -1 and total hip BMD T-scores ≥ -1 groups. The association between the primary outcome and main independent variables was evaluated by Pearson bivariate correlation and multivariate linear regression.

RESULTS

195 female and 415 male patients with T2DM were identified. In male patients with T2DM, bilateral ulnar, median, and tibial MCVs and bilateral sural SCVs were lower in the total hip BMD T-score < -1 group than T-score ≥ -1 group (P < 0.05). Bilateral ulnar, median, and tibial MCVs, and bilateral sural SCVs showed positive correlations with total hip BMD T-score in male patients with T2DM (P < 0.05). Bilateral ulnar and tibial MCVs, bilateral sural SCVs, and composite MCV SCV and MSCV Z-scores were independently and positively associated with total hip BMD T-score in male patients with T2DM, respectively (P < 0.05). NCV did not show significant correlation with the total hip BMD T-score in female patients with T2DM.

CONCLUSION

NCV showed positive association with total hip BMD in male patients with T2DM. A decline in NCV indicates an elevated risk of low BMD (osteopenia/osteoporosis) in male patients with T2DM.

Diabetic Neuropathy: Prevalence and Impact on Quality of Life in Al-Ahsa, Saudi Arabia

Objective This study aims to measure the prevalence of diabetic neuropathy (DN) in patients with type 1 and type 2 diabetes mellitus (DM) and to explore the impact of DN on quality of life (QoL) in type 1 and type 2 DM patients in Al-Ahsa, Saudi Arabia. Methods This cross-sectional study targeted type 1 and type 2 DM patients who live in Al-Ahsa, Saudi Arabia. Self-reported online questionnaires distributed randomly on social media were used. The survey included three parts: sociodemographic data, the Self-Administered Leeds Assessment of Neuropathic Symptoms and Signs (S-LANSS) questionnaire, and the modified Arabic Diabetes Quality of Life (DQoL) questionnaire. The data have been collected from April 2022 to May 2022. Results The study included participants (n = 329) of both type 1 and type 2 DM. Patients' age ranged from 18 to 82 years with a mean age of 45.9 ± 15.2 years. A total of 166 (50.5%) patients were males and 319 (97%) were Saudi nationals. The prevalence of DN in the study population was 44.1%. Of the patients with DN, 73.1% have low QoL, which means DN increased the risk of low QoL by about four times (OR = 3.9; 95% CI: 2.5-6.3). Conclusion In conclusion, the study showed that the prevalence of DN in Al-Ahsa, Saudi Arabia was 44.1%. The presence of DN was associated with reduced QoL. Type 2 DM, low educational level, and the presence of other comorbidities were significantly associated with low QoL.

Novel Nanotechnological Approaches for Targeting Dorsal Root Ganglion (DRG) in Mitigating Diabetic Neuropathic Pain (DNP)

Diabetic neuropathy is the most entrenched complication of diabetes. Usually, it affects the distal foot and toes, which then gradually approaches the lower part of the legs. Diabetic foot ulcer (DFU) could be one of the worst complications of diabetes mellitus. Long-term diabetes leads to hyperglycemia, which is the utmost contributor to neuropathic pain. Hyperglycemia causing an upregulation of voltage-gated sodium channels in the dorsal root ganglion (DRG) was often observed in models of neuropathic pain. DRG opening frequency increases intracellular sodium ion levels, which further causes increased calcium channel opening and stimulates other pathways leading to diabetic peripheral neuropathy (DPN). Currently, pain due to diabetic neuropathy is managed via antidepressants, opioids, gamma-aminobutyric acid (GABA) analogs, and topical agents such as capsaicin. Despite the availability of various treatment strategies, the percentage of patients achieving adequate pain relief remains low. Many factors contribute to this condition, such as lack of specificity and adverse effects such as light-headedness, languidness, and multiple daily doses. Therefore, nanotechnology outperforms in every aspect, providing several benefits compared to traditional therapy such as site-specific and targeted drug delivery. Nanotechnology is the branch of science that deals with the development of nanoscale materials and products, even smaller than 100 nm. Carriers can improve their efficacy with reduced side effects by incorporating drugs into the novel delivery systems. Thus, the utilization of nanotechnological approaches such as nanoparticles, polymeric nanoparticles, inorganic nanoparticles, lipid nanoparticles, gene therapy (siRNA and miRNA), and extracellular vesicles can extensively contribute to relieving neuropathic pain.

Glycated albumin and HbA1c as markers of lower extremity disease inUS adults with and without diabetes

AIM

We evaluated the associations of two biomarkers of hyperglycemia-hemoglobin A1c(HbA1c) and glycated albumin-with lower extremity disease in US adultsoverall and by diabetes status.

METHODS

We conducted a cross-sectional study of adult participants aged ≥ 40 years who attended the National Health and Nutrition Examination Survey (NHANES) 1999-2004 (unweighted N = 5,785). We used logistic regression to evaluate the associations of HbA1c and glycated albumin with lower extremity disease: peripheral neuropathy (assessed by monofilament test), peripheral artery disease (assessed by ankle-brachial index), history of foot ulcer, or amputation. All analyses were weighted and accounted for the complex NHANES sample survey design.

RESULTS

The prevalence of lower extremity disease was 17.4% (15.9% in adults without diabetes and 33.2% in adults with diabetes). HbA1c and glycated albumin were not significantly associated with lower extremity disease in adults without diabetes. However, we observed significant associations of both HbA1c (OR 1.19 per 1-% point increase, 95 %CI 1.06-1.34) and glycated albumin (OR 1.06 per 1-% point increase, 95 %CI 1.02-1.10) with lower extremity disease in adults with diabetes after adjustment. The patterns of association were similar for HbA1c and glycated albumin (P-for-seemingly-unrelated-regression = 0.60), with strong linear associations observed at high (diabetic) levels of both biomarkers.

CONCLUSIONS

Our study suggests the importance of diabetes prevention and glycemic control in adults with diabetes to reduce the burden of lower extremity disease.

Role of Mechanoinsensitive Nociceptors in Painful Diabetic Peripheral Neuropathy

The cutaneous mechanisms that trigger spontaneous neuropathic pain in diabetic peripheral neuropathy (PDPN) are far from clear. Two types of nociceptors are found within the epidermal and dermal skin layers. Small-diameter lightly myelinated Aδ and unmyelinated C cutaneous mechano and heat-sensitive (AMH and CMH) and C mechanoinsensitive (CMi) nociceptors transmit pain from the periphery to central nervous system. AMH and CMH fibers are mainly located in the epidermis, and CMi fibers are distributed in the dermis. In DPN, dying back intra-epidermal AMH and CMH fibers leads to reduced pain sensitivity, and the patients exhibit significantly increased pain thresholds to acute pain when tested using traditional methods. The role of CMi fibers in painful neuropathies has not been fully explored. Microneurography has been the only tool to access CMi fibers and differentiate AMH, CMH, and CMi fiber types. Due to the complexity, its use is impractical in clinical settings. In contrast, a newly developed diode laser fiber selective stimulation (DLss) technique allows to safely and selectively stimulate Aδ and C fibers in the superficial and deep skin layers. DLss data demonstrate that patients with painful DPN have increased Aδ fiber pain thresholds, while C-fiber thresholds are intact because, in these patients, CMi fibers are abnormally spontaneously active. It is also possible to determine the involvement of CMi fibers by measuring the area of DLss-induced neurogenic axon reflex flare. The differences in AMH, CMH, and CMi fibers identify patients with painful and painless neuropathy. In this review, we will discuss the role of CMi fibers in PDPN.

Pathophysiology and Molecular Imaging of Diabetic Foot Infections

Diabetic foot infection is the leading cause of non-traumatic lower limb amputations worldwide. In addition, diabetes mellitus and sequela of the disease are increasing in prevalence. In 2017, 9.4% of Americans were diagnosed with diabetes mellitus (DM). The growing pervasiveness and financial implications of diabetic foot infection (DFI) indicate an acute need for improved clinical assessment and treatment. Complex pathophysiology and suboptimal specificity of current non-invasive imaging modalities have made diagnosis and treatment response challenging. Current anatomical and molecular clinical imaging strategies have mainly targeted the host's immune responses rather than the unique metabolism of the invading microorganism. Advances in imaging have the potential to reduce the impact of these problems and improve the assessment of DFI, particularly in distinguishing infection of soft tissue alone from osteomyelitis (OM). This review presents a summary of the known pathophysiology of DFI, the molecular basis of current and emerging diagnostic imaging techniques, and the mechanistic links of these imaging techniques to the pathophysiology of diabetic foot infections.

Pathophysiology and Molecular Imaging of Diabetic Foot Infections

Diabetic foot infection is the leading cause of non-traumatic lower limb amputations worldwide. In addition, diabetes mellitus and sequela of the disease are increasing in prevalence. In 2017, 9.4% of Americans were diagnosed with diabetes mellitus (DM). The growing pervasiveness and financial implications of diabetic foot infection (DFI) indicate an acute need for improved clinical assessment and treatment. Complex pathophysiology and suboptimal specificity of current non-invasive imaging modalities have made diagnosis and treatment response challenging. Current anatomical and molecular clinical imaging strategies have mainly targeted the host's immune responses rather than the unique metabolism of the invading microorganism. Advances in imaging have the potential to reduce the impact of these problems and improve the assessment of DFI, particularly in distinguishing infection of soft tissue alone from osteomyelitis (OM). This review presents a summary of the known pathophysiology of DFI, the molecular basis of current and emerging diagnostic imaging techniques, and the mechanistic links of these imaging techniques to the pathophysiology of diabetic foot infections.

Prevalence of peripheral neuropathy defined by monofilament insensitivity in middle-aged and older adults in two US cohorts

Peripheral neuropathy is associated with substantial morbidity, but risk factors other than diabetes are largely uncharacterized. The aim of this study was to describe the prevalence and risk factors for peripheral neuropathy in adults with and without diabetes from two different population-based studies in the US. We performed a cross-sectional analysis of 5200 black and white participants from NHANES (1999-2004, age 40-85 years) and 3362 black and white participants from the ARIC Study (2016-2017, age 70-89 years) who underwent monofilament testing for peripheral neuropathy using a shared protocol. We used logistic regression to quantify age, sex, and race-adjusted risk factor associations for peripheral neuropathy among middle-aged (40-69 years) and older (≥ 70 years) adults. The age, sex, and race-adjusted prevalence of peripheral neuropathy (decreased sensation on monofilament testing) was 10.4% for middle-aged adults in NHANES, 26.8% for older adults in NHANES, and 39.2% for older adults in ARIC. Diabetes was an important risk factor, but more strongly associated with peripheral neuropathy in middle-aged (OR ~ 5 for long-standing diabetes) compared to older adults (ORs ~ 1.5-2). Male sex (ORs ~ 2), black race (ORs ~ 1.3-1.5), and greater height (ORs ~ 1.5-3) were robust risk factors for peripheral neuropathy. Other risk factors included body mass index, education, and peripheral artery disease. The burden of peripheral neuropathy defined by abnormal monofilament testing among older adults is substantial, even among adults without diabetes. Studies are needed to understand the etiology and prognosis of peripheral neuropathy in the absence of diabetes.

Screening for Diabetes and Prediabetes

Overt type 2 diabetes mellitus (T2DM) is preceded by prediabetes and latent diabetes (lasts 9-12 years). Key dysglycemia screening tests are fasting plasma glucose and hemoglobin A1C. Screen-detected T2DM benefits from multifactorial management of cardiovascular risk beyond glycemia. Prediabetes is best addressed by lifestyle modification, with the goal of preventing T2DM. Although there is no trial evidence of prediabetes/T2DM screening effectiveness, simulations suggest that clinic-based opportunistic screening of high-risk individuals is cost-effective. The most rigorous extant recommendations are those of the American Diabetes Association and US Preventive Services Task Force, which advise opportunistic 3-yearly screening.

A Cross-Sectional Web Survey of Satisfaction with Treatment for Pain in Participants with Suspected Diabetic Peripheral Neuropathic Pain in Both Feet

Introduction

Diabetic peripheral neuropathic pain (DPNP), a symptom of diabetic polyneuropathy (DPN), is underdiagnosed in people with diabetes. To date, no studies have determined the relationship between diagnosis of DPN and satisfaction with treatment for pain. Additionally, the factors that influence satisfaction with treatment for pain remain unknown. This questionnaire study was conducted to understand satisfaction with treatment for pain among participants with diabetes who experienced bilateral pain or numbness in their feet.

Methods

This cross-sectional, observational, web-based questionnaire study for participants with diabetes and suspected DPNP was conducted in Japan. Potential respondents were registered in the INTAGE Disease Panel or the Rakuten Insight Disease Panel. The primary endpoint was the number and percentage of participants who were satisfied with their DPNP treatment. Secondary endpoints included participant opinions regarding treatment-related efficacy, side effects, and economic burden, and factors affecting satisfaction with treatment.

Results

The questionnaire was accessed by 7565 potential participants; 777 met the eligibility criteria (final analysis set). Satisfaction with treatment for bilateral foot pain was low (satisfied, 27.9%; neither satisfied nor unsatisfied, 42.2%; unsatisfied, 23.4%; very unsatisfied, 6.4%). Participants were somewhat more satisfied with treatment side effects than with treatment efficacy and economic burden. Satisfaction with treatment mainly differed by improvement in actions in daily life, improvement in quality of life, and communication with doctors. The diagnostic testing rate for DPN was low, and diagnosis was more common in participants who complained of symptoms of pain and numbness (any visit) versus those who did not.

Conclusion

Participants with diabetes who experience bilateral foot pain or numbness reported a low level of satisfaction with treatment for pain.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12325-021-01810-x.

People with diabetes may develop diabetic polyneuropathy and experience diabetic peripheral neuropathic pain, which is often felt as pain or numbness below the knee. This study aimed to learn whether participants with diabetes who had pain or numbness in both feet were satisfied with the pain treatment they received. Factors affecting satisfaction with treatment were also evaluated. Potential participants with diabetes identified from two commercial databases (INTAGE Disease Panel or Rakuten Insight Disease Panel) of patients with various diseases living in Japan were asked to respond to our web survey. Besides satisfaction with treatment for pain, participants were asked about how well their treatment was working, treatment side effects, how treatment affected them financially, and what factors affected their satisfaction with treatment. The main finding was that only 27.9% of participants were satisfied with their treatment for foot pain and numbness. Generally, participants were more satisfied with treatment side effects than they were with how well the treatment worked, and how treatment affected them financially. Participants were more satisfied if they had an improved ability to perform everyday activities or experienced an improvement in quality of life with treatment. Participants were also more satisfied if they communicated well with their physician. The rate of diagnostic tests was low; however, participants were more likely to receive a diagnostic test when they complained of pain or numbness than when they did not. On the basis of these findings, we think improvements in the treatment of foot pain or numbness in those with diabetes are needed.

Foot deformities in patients with diabetic mellitus (with and without peripheral neuropathy)

BACKGROUND

Diabetic peripheral neuropathy (DPN) is one of the most common complications in diabetes mellitus. It is the disorder that most commonly affects the feet of people with diabetes. The aim of the present study is to determine the relationship between DPN and the presence of deformities in the foot.

MATERIAL AND METHODS

A descriptive observational study was conducted of 111 patients diagnosed with Diabetes Mellitus (DM) type 1 or 2. All participants were aged at least 18 years and were previously informed in detail about the aims and procedures of the study.

RESULTS

Regarding the presence of DPN, the only significant relationships were found for the right foot with the deformity of the second toe (claw, hammer or mallet) (p = 0.017, OR 0.29 [0.10-0.83]) and for the left foot with the deformity of the second toe (p = 0.048; OR: 0.37 [0.14-1.01]), third toe (p = 0.012; OR: 0.29 [0.11-0.79]) and the presence of hallux extensus (p = 0.05; OR: 8.27 [1.05-64.98]).

CONCLUSIONS

A significant number of foot deformities were observed among these patients with DM, regardless of the presence of DPN. These deformities should be carefully evaluated in order to determine the most appropriate treatment at an early stage, which will reduce the risk of ulceration. Although it should be use with caution to be transferrable to the general population with peripheral neuropathy.

Efficacy of exercise on balance, fear of falling, and risk of falls in patients with diabetic peripheral neuropathy: a systematic review and meta-analysis

Diabetic peripheral neuropathy (DPN) is the most common complication of diabetes mellitus. Our objective was to evaluate the efficacy of exercise interventions in DPN patients from randomized controlled trials. The primary outcomes were the risk of falls, fear of falling, balance and quality of life. Two reviewers independently selected studies from Embase, Medline, LILACS, CENTRAL, and PEDro. They assessed the risk of bias and extracted data from the trials. The relative risk (RR) and the differences between means (MD) were calculated with a 95% confidence interval (CI) and used as the effect size. We used a random-effects model to pool results across studies, and the Grading of Recommendations Assessment, Development, and Evaluation system to evaluate the certainty of evidence. Eight trials were included. No clear effect was observed in the risk of falls (RR: 0.93, 95% CI: 0.41 to 2.09, 79 participants, 1 trial, low-certainty evidence). Regarding fear of falling, using the Falls Efficacy Scale, a small difference in favor of the intervention was observed (MD: -2.42, 95%, CI: -4.7 to -0.15, 3 trials, 185 participants, low-certainty evidence). The meta-analysis of balance using the unipedal stance test showed a small difference in favor of the intervention. One study evaluated quality of life, and in the mental score there was a MD in favor of the intervention. In DPN patients, a combination of gait, balance, and functional training improved balance, the fear of falling, quality of life in the mental score, but not the risk of falls.

A Cross-sectional Survey of Patients with Suspected Diabetic Peripheral Neuropathic Pain in Japan

Objective The burden of diabetic peripheral neuropathic pain (DPNP) is poorly understood. The present study reported on the current status of DPNP in Japan, to improve our understanding of this condition among healthcare providers and inform future clinical research on its prevalence, diagnosis, and management. Methods A cross-sectional, observational study (UMIN000037023) was conducted via a web-based survey. The primary endpoints were the frequency of patients with bilateral foot symptoms, consulting a doctor, understanding DPNP, and reporting problems in daily life, as well as the treatment awareness of patients. Patients Adults ≥20 years old who were registered in the Rakuten Insight Disease Panel and receiving anti-diabetic therapy in Japan were included. Results Bilateral foot pain symptoms were reported by 1,768/7,754 (22.8%) respondents, most commonly intense numbness (13.0%). Of those with symptoms, 55.3% consulted a doctor; the most common reason for not seeking consultation was feeling that symptoms were insufficiently severe to bother their doctor (89.4%). Nearly 60% reported understanding the causes of their symptoms, with diabetes-associated neurologic deficits (58.8%) most commonly identified. About one-quarter reported daily life problems, including an inability to walk for long periods (58.3%) and feeling anxious (58.1%). Treatment awareness was reported by 18.2%; oral medications were commonly recognized (64.6%). Conclusion In Japan, 22.8% of patients with diabetes have bilateral foot pain symptoms; some experience problems in their daily life without understanding the causes of their symptoms. This supports the importance of actions to increase awareness and minimize DPNP-associated impairment of daily life in patients with diabetes.

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.

Advances in Screening, Early Diagnosis and Accurate Staging of Diabetic Neuropathy

The incidence of both type 1 and type 2 diabetes is increasing worldwide. Diabetic peripheral neuropathy (DPN) is among the most distressing and costly of all the chronic complications of diabetes and is a cause of significant disability and poor quality of life. This incurs a significant burden on health care costs and society, especially as these young people enter their peak working and earning capacity at the time when diabetes-related complications most often first occur. DPN is often asymptomatic during the early stages; however, once symptoms and overt deficits have developed, it cannot be reversed. Therefore, early diagnosis and timely intervention are essential to prevent the development and progression of diabetic neuropathy. The diagnosis of DPN, the determination of the global prevalence, and incidence rates of DPN remain challenging. The opinions vary about the effectiveness of the expansion of screenings to enable early diagnosis and treatment initiation before disease onset and progression. Although research has evolved over the years, DPN still represents an enormous burden for clinicians and health systems worldwide due to its difficult diagnosis, high costs related to treatment, and the multidisciplinary approach required for effective management. Therefore, there is an unmet need for reliable surrogate biomarkers to monitor the onset and progression of early neuropathic changes in DPN and facilitate drug discovery. In this review paper, the aim was to assess the currently available tests for DPN's sensitivity and performance.

Associations of Cardiac, Kidney, and Diabetes Biomarkers With Peripheral Neuropathy among Older Adults in the Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

The aim of this study was to assess the association of high-sensitivity cardiac troponin (hs-cTnT) and other cardiac, kidney, hyperglycemia, and inflammatory biomarkers with peripheral neuropathy (PN) in a community-based population.

METHODS

We conducted a cross-sectional analysis of 3056 black and white participants in the Atherosclerosis Risk in Communities (ARIC) study who underwent standardized monofilament PN testing and had measures of cardiac function (hs-cTnT, N-terminal pro-B-type natriuretic peptide [NT-proBNP], and growth differentiation factor 15 [GDF15]), kidney function (serum creatinine, cystatin C, β-2 microglobulin, urine albumin-to-creatinine ratio), hyperglycemia (fasting glucose, hemoglobin A1c [Hb A1c], fructosamine, glycated albumin, 1,5-anhydroglucitol), and inflammation (C-reactive protein) assessed at visit 6 (2016-2017; age 71-94 years). We used logistic regression to assess the associations of these biomarkers (modeled in diabetes-specific tertiles) with PN in older adults with and without diabetes after adjusting for traditional risk factors.

RESULTS

In total, 33.5% of participants had PN (37.3% with diabetes and 31.9% without diabetes). There was an independent association of hs-cTnT with PN regardless of diabetes status (diabetes T3 vs. T1: odds ratio [OR], 2.15 [95% CI, 1.44-3.22]; no diabetes: OR, 2.31 [95%CI, 1.76-3.03]; P = 0.72 for interaction). Among participants without diabetes, there were also significant associations of NT-proBNP (OR, 1.40 [95% CI, 1.08-1.81]) and urine albumin-to-creatinine ratio (OR, 1.55 [95% CI, 1.22-1.97]) with PN. Associations of hyperglycemia biomarkers including Hb A1c (OR, 1.76 [95% CI, 1.22-2.54]), fructosamine (OR, 1.71 [95% CI, 1.19-2.46]), and glycated albumin (OR, 1.45 [95% CI, 1.03-2.03]) with PN were significant only among participants with diabetes.

CONCLUSIONS

Overall, hs-cTnT appears to be a global marker of end organ damage, including PN. Laboratory biomarkers may be able to help us identify those individuals with PN.

Cardiometabolic risk factors as determinants of peripheral nerve function: the Maastricht Study

AIMS/HYPOTHESIS

We aimed to examine associations of cardiometabolic risk factors, and (pre)diabetes, with (sensorimotor) peripheral nerve function.

METHODS

In 2401 adults (aged 40-75 years) we previously determined fasting glucose, HbA_1c, triacylglycerol, HDL- and LDL-cholesterol, inflammation, waist circumference, blood pressure, smoking, glucose metabolism status (by OGTT) and medication use. Using nerve conduction tests, we measured compound muscle action potential, sensory nerve action potential amplitudes and nerve conduction velocities (NCVs) of the peroneal, tibial and sural nerves. In addition, we measured vibration perception threshold (VPT) of the hallux and assessed neuropathic pain using the DN4 interview. We assessed cross-sectional associations of risk factors with nerve function (using linear regression) and neuropathic pain (using logistic regression). Associations were adjusted for potential confounders and for each other risk factor. Associations from linear regression were presented as standardised regression coefficients (β) and 95% CIs in order to compare the magnitudes of observed associations between all risk factors and outcomes.

RESULTS

Hyperglycaemia (fasting glucose or HbA_1c) was associated with worse sensorimotor nerve function for all six outcome measures, with associations of strongest magnitude for motor peroneal and tibial NCV, β_{fasting glucose} = -0.17 SD (-0.21, -0.13) and β_{fasting glucose} = -0.18 SD (-0.23, -0.14), respectively. Hyperglycaemia was also associated with higher VPT and neuropathic pain. Larger waist circumference was associated with worse sural nerve function and higher VPT. Triacylglycerol, HDL- and LDL-cholesterol, and blood pressure were not associated with worse nerve function; however, antihypertensive medication usage (suggestive of history of exposure to hypertension) was associated with worse peroneal compound muscle action potential amplitude and NCV. Smoking was associated with worse nerve function, higher VPT and higher risk for neuropathic pain. Inflammation was associated with worse nerve function and higher VPT, but only in those with type 2 diabetes. Type 2 diabetes and, to a lesser extent, prediabetes (impaired fasting glucose and/or impaired glucose tolerance) were associated with worse nerve function, higher VPT and neuropathic pain (p for trend <0.01 for all outcomes).

CONCLUSIONS/INTERPRETATION

Hyperglycaemia (including the non-diabetic range) was most consistently associated with early-stage nerve damage. Nonetheless, larger waist circumference, inflammation, history of hypertension and smoking may also independently contribute to worse nerve function.

Epidemiology of diabetes phenotypes and prevalent cardiovascular risk factors and diabetes complications in the National Health and Nutrition Examination Survey 2003-2014

AIMS

To characterize unique diabetes phenotypes among National Health and Nutrition Examination Survey (NHANES) participants and assess associations with race/ethnicity, cardiovascular disease (CVD) risk factors, and prevalent complications.

METHODS

We included participants (age ≥ 20 years) from NHANES exams 2003-04 through 2013-14 with diabetes (self-report of diabetes diagnosis or medication use, fasting glucose ≥7.0 mmol/L, random glucose ≥11.1 mmol/L, and glycated hemoglobin (HbA1c) ≥ 48 mmol/mol). We used k-means clustering to characterize unique diabetes subgroups based on data for age of diabetes diagnosis, body mass index (BMI), waist circumference, HbA1c, and years of insulin use. We estimated subgroup prevalence of CVD risk factors and microvascular complications, accounting for demographics and survey sampling.

RESULTS

Among 4300 adults with diabetes, we identified four unique subgroups of diabetes related to aging (AR, 51.3%), severe obesity (SO, 30.3%), severe hyperglycemia (SH, 12.5%), and young adulthood-onset (YA, 5.9%). We observed differences in subgroup proportion by race/ethnicity. Compared to the AR phenotype, all groups had higher HbA1c and BMI, the YA and SO groups had greater blood pressure, and the YA group had greater prevalence of renal, eye, and neuropathy complications.

CONCLUSIONS

Whether consideration of diabetes phenotypes with treatment strategies reduce diabetes incidence, morbidity, and mortality merits evaluation.

The association between perceived discrimination in midlife and peripheral neuropathy in a population-based cohort of women: the Study of Women's Health Across the Nation

PURPOSE

Peripheral neuropathy (PN) is a highly prevalent condition with serious sequelae. Many studies of the condition have been restricted to populations with diabetes, limiting evidence of potential contributing risk factors including salient psychosocial risk factors such as discrimination.

METHODS

The longitudinal Study of Women's Health Across the Nation was used to assess the relationship between perceived discrimination and prevalent PN in 1718 ethnically diverse midlife women. We used multivariable logistic regression to determine the association between perceived discrimination (Detroit Area Study Everyday Discrimination Scale) and PN (symptom questionnaire and monofilament testing) and conducted an assessment of the mediating effects of body mass index (BMI).

RESULTS

The prevalence of PN was 26.1% in the total sample and 40.9% among women with diabetes. Women who reported perceived discrimination had 29% higher odds of PN compared with women who did not report perceived discrimination (95% confidence interval, 1.01-1.66). Approximately 30% of the total effect of discrimination on PN was mediated indirectly by BMI.

CONCLUSIONS

More research is needed to determine the contributing factors to nondiabetic PN. Our findings reaffirm the impact of financial strain, BMI, and diabetes as significant correlates of PN and highlight discrimination as an important risk factor.

Epidemiology of Peripheral Neuropathy and Lower Extremity Disease in Diabetes

PURPOSE OF REVIEW

Diabetic peripheral neuropathy eventually affects nearly 50% of adults with diabetes during their lifetime and is associated with substantial morbidity including pain, foot ulcers, and lower limb amputation. This review summarizes the epidemiology, risk factors, and management of diabetic peripheral neuropathy and related lower extremity complications.

RECENT FINDINGS

The prevalence of peripheral neuropathy is estimated to be between 6 and 51% among adults with diabetes depending on age, duration of diabetes, glucose control, and type 1 versus type 2 diabetes. The clinical manifestations are variable, ranging from asymptomatic to painful neuropathic symptoms. Because of the risk of foot ulcer (25%) and amputation associated with diabetic peripheral neuropathy, aggressive screening and treatment in the form of glycemic control, regular foot exams, and pain management are important. There is an emerging focus on lifestyle interventions including weight loss and physical activity as well. The American Diabetes Association has issued multiple recommendation statements pertaining to diabetic neuropathies and the care of the diabetic foot. Given that approximately 50% of adults with diabetes will be affected by peripheral neuropathy in their lifetime, more diligent screening and management are important to reduce the complications and health care burden associated with the disease.

Post-9/11 Peripheral Neuropathy Symptoms among World Trade Center-Exposed Firefighters and Emergency Medical Service Workers

Peripheral neuropathy can result from numerous conditions including metabolic disorders, inflammatory disease, or exposure to environmental or biological toxins. We analyzed questionnaire data from 9239 Fire Department of the City of New York (FDNY) World Trade Center (WTC)-exposed firefighters and emergency medical service workers (EMS) to evaluate the association between work at the WTC site and subsequent peripheral neuropathy symptoms using the validated Diabetic Neuropathy Symptom (DNS) score. We grouped the population into an "Indicated" group with conditions known to be associated with paresthesia (N = 2059) and a "Non-Indicated" group without conditions known to be associated (N = 7180). The level of WTC exposure was categorized by time of arrival to the WTC. Overall, 25% of workers aged 40 and older reported peripheral neuropathy symptoms: 30.6% in the Indicated and 23.8% in the Non-Indicated groups, respectively. Multivariable logistic models performed on the Non-Indicated group, and on the Non-Indicated in comparison with non-WTC exposed National Health and Nutrition Examination Survey (NHANES), found that the highest level of WTC-exposure was significantly associated with DNS positive outcomes, after controlling for potential confounders. In conclusion, this study suggests that symptoms of peripheral neuropathy and paresthesias are common and are associated with WTC-exposure intensity.

A comparative analysis of skin substitutes used in the management of diabetic foot ulcers

OBJECTIVE

To compare the relative product cost and clinical outcomes of four skin substitutes used as adjunctive treatments for diabetic foot ulcers (DFUs).

METHOD

Medicare claims data from 2011 to 2014 were used to identify beneficiaries with diabetes and foot ulcers. Patients treated with one of four types of skin substitute (Apligraf, Dermagraft, OASIS, and MatriStem) were identified. The skin substitutes were compared on episode length; amputation rate; skin substitute utilisation; and skin substitute costs.

RESULTS

There were 13,193 skin substitute treatment episodes: Apligraf (HML) was used in 4926 (37.3%), Dermagraft (HSL) in 5530 (41.9%), OASIS (SIS) in 2458 (18.6%) and MatriStem (UBM) in 279 (2.1%). The percentage of DFUs that healed at 90 days were: UBM 62%; SIS 63%; HML 58%; and HSL 58%. Over the entire time, UBM was non-inferior to SIS (p<0.001), and either was significantly better than HML or HSL (p<0.005 in all four tests). HML was marginally superior to HSL (p=0.025 unadjusted for multiple testing). Medicare reimbursements for skin substitutes per DFU episode for UBM ($1435 in skin substitutes per episode) and SIS ($1901) appeared to be equivalent to each other, although non-inferiority tests were not significant. Both were less than HML ($5364) or HSL ($14,424) (p<0.0005 in all four tests). HML was less costly than HSL (p<0.0005).

CONCLUSION

Various types of skin substitutes appear to be able to confer important benefits to both patients with DFUs and payers. Analysis of the four skin-substitute types resulted in a demonstration that UBM and SIS were associated with both shorter DFU episode lengths and lower payer reimbursements than HML and HSL, while HML was less costly than HSL but equivalent in healing.

DECLARATION OF INTEREST

MM and NM are health economic consultants who completed and authored this analysis. They have no financial interest in ACell, Inc. Their fees were not contingent on the outcome of this analysis.

Significance of prediabetes as a nosological entity

Prediabetes is a glucose metabolism disorder considered as a distinct nosological entity which strongly predicts the development of type 2 diabetes mellitus. This nosological entity itself is a serious condition indicating an increased risk of atherosclerotic and oncological complications. In patients with prediabetes, other components of metabolic syndrome are usually present, such as arterial hypertension, obesity or dyslipidaemia, further increasing an individual's risk of morbidity and mortality. Prediabetes is a long-developing disorder which offers enough time for early diagnosis and intervention; it may even be reversible. This review summarizes current knowledge on the definition, detection, epidemiology, cardiovascular and other consequences of prediabetes. It also gives suggestions for future research, along with recommendations for clinical practice.

Sensory Polyneuropathies

PURPOSE OF REVIEW

This article describes the methods of diagnosis and management of the sensory-predominant polyneuropathies. To simplify the approach to this category of patients, sensory-predominant polyneuropathies are divided broadly into either small fiber (or pain-predominant) neuropathies and large fiber (or ataxia-predominant) neuropathies, of which the sensory neuronopathies (dorsal root ganglionopathies) are highlighted.

RECENT FINDINGS

Physicians can now easily perform skin biopsies in their offices, allowing access to the gold standard pathologic diagnostic tool for small fiber neuropathies. Additional diagnostic techniques, such as corneal confocal microscopy, are emerging. Recently, small fiber neuropathies have been associated with a broader spectrum of diseases, including fibromyalgia, sodium channel mutations, and voltage-gated potassium channel antibody autoimmune disease.

SUMMARY

Despite advances in diagnosing small fiber neuropathies and sensory neuronopathies, many of these neuropathies remain refractory to treatment. In select cases, early identification and treatment may result in better outcomes. "Idiopathic" should be a diagnosis of exclusion and a thorough investigation for treatable causes pursued.

Association of Hemoglobin A1c and Wound Healing in Diabetic Foot Ulcers

OBJECTIVE

This study evaluated the association between hemoglobin A_1c (A1C) and wound outcomes in patients with diabetic foot ulcers (DFUs).

RESEARCH DESIGN AND METHODS

We conducted a retrospective analysis of an ongoing prospective, clinic-based study of patients with DFUs treated at an academic institution during a 4.7-year period. Data from 270 participants and 584 wounds were included in the analysis. Cox proportional hazards regression was used to assess the incidence of wound healing at any follow-up time in relation to categories of baseline A1C and the incidence of long-term (≥90 days) wound healing in relation to tertiles of nadir A1C change and mean A1C change from baseline, adjusted for potential confounders.

RESULTS

Baseline A1C was not associated with wound healing in univariate or fully adjusted models. Compared with a nadir A1C change from baseline of -0.29 to 0.0 (tertile 2), a nadir A1C change of 0.09 to 2.4 (tertile 3) was positively associated with long-term wound healing in the subset of participants with baseline A1C <7.5% (hazard ratio [HR] 2.07; 95% CI 1.08-4.00), but no association with wound healing was seen with the mean A1C change from baseline in this group. Neither nadir A1C change nor mean A1C change were associated with long-term wound healing in participants with baseline A1C ≥7.5%.

CONCLUSIONS

There does not appear to be a clinically meaningful association between baseline or prospective A1C and wound healing in patients with DFUs. The paradoxical finding of accelerated wound healing and increase in A1C in participants with better baseline glycemic control requires confirmation in further studies.

Descriptive vs mechanistic scientific approach to study wound healing and its inhibition: Is there a value of translational research involving human subjects?

The clinical field of wound healing is challenged by numerous hurdles. Not only are wound-healing disorders complex and multifactorial, but the corresponding patient population is diverse, often elderly and burdened by multiple comorbidities such as diabetes and cardiovascular disease. The care of such patients requires a dedicated, multidisciplinary team of physicians, surgeons, nurses and scientists. In spite of the critical clinical need, it has been over 15 years since a treatment received approval for efficacy by the FDA in the United States. Among the reasons contributing to this lack of effective new treatment modalities is poor understanding of mechanisms that inhibit healing in patients. Additionally, preclinical models do not fully reflect the disease complexity of the human condition, which brings us to a paradox: if we are to use a "mechanistic" approach that favours animal models, we can dissect specific mechanisms using advanced genetic, molecular and cellular technologies, with the caveat that it may not be directly applicable to patients. Traditionally, scientific review panels, for either grant funding or manuscript publication purposes, favour such "mechanistic" approaches whereby human tissue analyses, deemed "descriptive" science, are characterized as a "fishing expedition" and are considered "fatally flawed." However, more emerging evidence supports the notion that the use of human samples provides significant new knowledge regarding the molecular and cellular mechanisms that control wound healing and contribute to inhibition of the process in patients. Here, we discuss the advances, benefits and challenges of translational research in wound healing focusing on human subject research.

Diabetes and obesity are the main metabolic drivers of peripheral neuropathy

Objective

To determine the associations between individual metabolic syndrome (MetS) components and peripheral neuropathy in a large population‐based cohort from Pinggu, China.

Methods

A cross‐sectional, randomly selected, population‐based survey of participants from Pinggu, China was performed. Metabolic phenotyping and neuropathy outcomes were performed by trained personnel. Glycemic status was defined according to the American Diabetes Association criteria, and the MetS using modified consensus criteria (body mass index instead of waist circumference). The primary peripheral neuropathy outcome was the Michigan Neuropathy Screening Instrument (MNSI) examination. Secondary outcomes were the MNSI questionnaire and monofilament testing. Multivariable models were used to assess for associations between individual MetS components and peripheral neuropathy. Tree‐based methods were used to construct a classifier for peripheral neuropathy using demographics and MetS components.

Results

The mean (SD) age of the 4002 participants was 51.6 (11.8) and 51.0% were male; 37.2% of the population had normoglycemia, 44.0% prediabetes, and 18.9% diabetes. The prevalence of peripheral neuropathy increased with worsening glycemic status (3.25% in normoglycemia, 6.29% in prediabetes, and 15.12% in diabetes, P < 0.0001). Diabetes (odds ratio [OR] 2.60, 95% CI 1.77–3.80) and weight (OR 1.09, 95% CI 1.02–1.18) were significantly associated with peripheral neuropathy. Age, diabetes, and weight were the primary splitters in the classification tree for peripheral neuropathy.

Interpretation

Similar to previous studies, diabetes and obesity are the main metabolic drivers of peripheral neuropathy. The consistency of these results reinforces the urgent need for effective interventions that target these metabolic factors to prevent and/or treat peripheral neuropathy.

Association Between Metabolic Syndrome Components and Polyneuropathy in an Obese Population

Importance

Past studies have shown an association between metabolic syndrome and polyneuropathy, but the precise components that drive this association remain unclear.

Objectives

To determine the prevalence of polyneuropathy stratified by glycemic status in well-characterized obese and lean participants and investigate the association of specific components of metabolic syndrome with polyneuropathy.

Design, Setting, and Participants

We performed a cross-sectional, observational study from November 1, 2010, to December 31, 2014, in obese participants (body mass index [calculated as weight in kilograms divided by height in meters squared] of 35 or more with no comorbid conditions or 32 or more with at least 1 comorbid condition) from a weight management program and lean controls from a research website. The prevalence of neuropathy, stratified by glycemic status, was determined, and a Mantel-Haenszel χ2 test was used to investigate for a trend. Logistic regression was used to model the primary outcome of polyneuropathy as a function of the components of metabolic syndrome after adjusting for demographic factors. Participants also completed quantitative sudomotor axon reflex testing, quantitative sensory testing, the neuropathy-specific Quality of Life in Neurological Disorders instrument, and the short-form McGill Pain Questionnaire.

Exposures

Components of metabolic syndrome (as defined by the National Cholesterol Education Program Adult Treatment Panel III), including glycemic status (as defined by the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus).

Main Outcomes and Measures

Toronto consensus definition of probable polyneuropathy. Secondary outcomes included intraepidermal nerve fiber density and nerve conduction study parameters.

Results

We enrolled 102 obese participants (mean [SD] age, 52.9 [10.2] years; 48 men and 54 women; 45 with normoglycemia [44.1%], 31 with prediabetes [30.4%], and 26 with type 2 diabetes [25.5%]) and 53 lean controls (mean [SD] age, 48.5 [9.9] years; 16 men and 37 women). The prevalence of polyneuropathy was 3.8% in lean controls (n = 2), 11.1% in the obese participants with normoglycemia (n = 5), 29% in the obese participants with prediabetes (n = 9), and 34.6% in the obese participants with diabetes (n = 9) (P < .01 for trend). Age (odds ratio, 1.09; 95% CI, 1.02-1.16), diabetes (odds ratio, 4.90; 95% CI, 1.06-22.63), and waist circumference (odds ratio, 1.24; 95% CI, 1.00-1.55) were significantly associated with neuropathy in multivariable models. Prediabetes (odds ratio, 3.82; 95% CI, 0.95-15.41) was not significantly associated with neuropathy.

Conclusions and Relevance

The prevalence of polyneuropathy is high in obese individuals, even those with normoglycemia. Diabetes, prediabetes, and obesity are the likely metabolic drivers of this neuropathy.

Trial Registration

clinicaltrials.gov Identifier: NCT02689661.

Mediators of diabetic neuropathy: is hyperglycemia the only culprit?

PURPOSE OF REVIEW

Diabetic peripheral neuropathy (DPN) is a disabling, highly prevalent complication of both type 1 and type 2 diabetes mellitus (T1DM and T2DM). Large clinical studies support the concept that, in addition to hyperglycemia, components of the metabolic syndrome (MetS) may underlie the pathogenesis of DPN, especially in T2DM. This review will present the evidence supporting the MetS and its individual components as potential causal factors for the development of neuropathy.

RECENT FINDINGS

In addition to poor glycemic control and duration of diabetes, components of MetS such as dyslipidemia, obesity, and hypertension may have an important impact on the prevalence of DPN. Obesity and prediabetes have the most data to support their role in neuropathy, whereas hypertension and dyslipidemia have more mixed results. Nonmetabolic factors, such as genetic susceptibility, age, height, sex, smoking, and alcohol, have also been highlighted as potential risk factors in peripheral neuropathy, although the exact contribution of these factors to DPN remains unknown.

SUMMARY

DPN is a chronic and disabling disease, and the accurate identification and modification of DPN risk factors is important for clinical management. Recent data support a role for components of the MetS and other risk factors in the development of DPN, offering novel targets beyond hyperglycemia for therapeutic development.

The amputation prevention initiative

BACKGROUND

The Amputation Prevention Initiative is a project conducted jointly by the Massachusetts Public Health Association and the Massachusetts Podiatric Medical Society that seeks to study methods to reduce nontraumatic lower-extremity amputations from diabetes.

METHODS

To determine the rate of diabetes-related lower-extremity amputations in Massachusetts and identify the groups most at risk, hospital billing and discharge data were analyzed. To examine the components of the diabetic foot examination routinely performed by general practitioners, surveys were conducted in conjunction with physician meetings in Massachusetts (n = 149) and in six other states (n = 490).

RESULTS

The average age-adjusted number of diabetes-related lower-extremity amputations in 2004 was 30.8 per 100,000 and 5.3 per 1,000 diabetic patients in MA, with high-risk groups being identified as men and black individuals. Among the general practitioners surveyed in Massachusetts, only 2.01% reported routinely conducting all four key components of the diabetic foot examination, with 28.86% reporting not performing any components.

CONCLUSIONS

These findings suggest that many general practitioners may be failing to perform the major components of the diabetic foot examination believed to prevent foot ulcers and lower-extremity amputations.

Non-traumatic lower limb amputation in patients with end-stage renal failure on dialysis: an Australian perspective

BACKGROUND

End-stage renal failure (ESRF) and dialysis have been identified as a risk factor for lower limb amputations (LLAs). High rate of ESRF amongst the Australian population has been reported, however till date no study has been published identifying magnitude and risk factors of LLA in subjects on renal dialysis.

OBJECTIVE

The study aims to document trends in the prevalence and identify risk factors of non-traumatic LLA in Australian patients on dialysis.

METHODS

A retrospective review of all patients (218) who attended the regional dialysis center between 1st January 2009 and 31st December 2013 was conducted. Demographic, clinical and biochemical data were analyzed.

RESULTS

We identified a high prevalence of 13.3% of LLAs amongst Australian patients with ESRF on dialysis at our center. The associated risk factors were the presence of diabetes (OR 1.67 [1.49-1.88] p < 0.001), history of foot ulceration (OR 81 [18.20-360.48] p < 0.001), peripheral arterial disease (OR 31.29 [9.02-108.56] p < 0.001), peripheral neuropathy (OR 31.29 [9.02-108.56] p < 0.001), foot deformity (OR 23.62 [5.82-95.93] p < 0.001), retinopathy (OR 6.08 [2.64-14.02] p < 0.001), dyslipidemia (OR 4.6 [1.05-20.05] p= 0.049) and indigenous background (OR 3.39 [1.38-8.33] p= 0.01). 75% of the amputees had aboriginal heritage. We also identified higher HbA1c and CRP levels as well as low serum albumin, hemoglobin and vitamin D levels to have a strong association with LLAs (p < 0.05).

CONCLUSION

There is high prevalence of LLAs amongst Australian indigenous patients with diabetes on dialysis in North Queensland. Other strongly associated risk factors include history of foot ulceration, foot deformity and peripheral neuropathy as well as high HbA1c levels and low serum albumin levels.

Metabolic Syndrome Components Are Associated With Symptomatic Polyneuropathy Independent of Glycemic Status

OBJECTIVE

Previous studies demonstrate that the metabolic syndrome is associated with distal symmetric polyneuropathy (DSP). We aimed to determine the magnitude of this effect and the precise components involved.

RESEARCH DESIGN AND METHODS

We determined the symptomatic DSP prevalence in the Health, Aging, and Body Composition (Health ABC) study (prospective cohort study, with subjects aged 70-79 years at baseline), stratified by glycemic status (glucose tolerance test) and the number of additional metabolic syndrome components (updated National Cholesterol Education Program/Adult Treatment Panel III definition). DSP was defined as neuropathic symptoms (questionnaire) plus at least one of three confirmatory tests (heavy monofilament, peroneal conduction velocity, and vibration threshold). Multivariable logistic and linear regression evaluated the association of metabolic syndrome components with DSP in cross-sectional and longitudinal analyses.

RESULTS

Of 2,382 participants with neuropathy measures (mean age 73.5 ± 2.9 years, 38.2% black, 51.7% women), 21.0% had diabetes, 29.9% prediabetes, 52.8% metabolic syndrome, and 11.1% DSP. Stratified by glycemic status, DSP prevalence increased as the number of metabolic syndrome components increased (P = 0.03). Diabetes (cross-sectional model, odds ratio [OR] 1.65 [95% CI 1.18-2.31]) and baseline hemoglobin A1C (longitudinal model, OR 1.42 [95% CI 1.15-1.75]) were the only metabolic syndrome measures significantly associated with DSP. Waist circumference and HDL were significantly associated with multiple secondary neuropathy outcomes.

CONCLUSIONS

Independent of glycemic status, symptomatic DSP is more common in those with additional metabolic syndrome components. However, the issue of which metabolic syndrome components drive this association, in addition to hyperglycemia, remains unclear. Larger waist circumference and low HDL may be associated with DSP, but larger studies with more precise metabolic measures are needed.

Guiding diabetes screening and prevention: rationale, recommendations and remaining challenges

Advances made in diabetes management are not sufficient to reduce morbidity, mortality and cost without making prevention efforts at various levels imperative for substantial impact. Research has demonstrated the efficacy of lifestyle intervention and medications in preventing type 2 diabetes among diverse high-risk groups commonly identified with oral glucose tolerance testing. Efficacy, sustainability and safety data are most comprehensive for lifestyle and metformin, with other medications also demonstrating efficacy and potential in the pharmacoprevention of diabetes. Subsequent implementation studies have demonstrated feasibility of lifestyle intervention programs at health centers, communities, and at local and national government levels. Challenges remain in widespread translation and reaching and engaging at-risk individuals and populations.

Peripheral Neuropathy and Nerve Dysfunction in Individuals at High Risk for Type 2 Diabetes: The PROMISE Cohort

OBJECTIVE

Emerging evidence suggests that peripheral neuropathy begins in the early stages of diabetes pathogenesis. Our objective was to describe the prevalence of peripheral neuropathy and nerve dysfunction according to glucose tolerance and metabolic syndrome status and examine how these conditions are associated with neurological changes in individuals at risk for type 2 diabetes.

RESEARCH DESIGN AND METHODS

We studied 467 individuals in the longitudinal PROMISE (Prospective Metabolism and Islet Cell Evaluation) cohort. Peripheral neuropathy was defined by Michigan Neuropathy Screening Instrument (MNSI) scores (>2), and the severity of nerve dysfunction was measured objectively by vibration perception thresholds (VPTs) using a neurothesiometer. Metabolic syndrome was defined using the International Diabetes Federation/American Heart Association harmonized criteria.

RESULTS

The prevalence of peripheral neuropathy was 29%, 49%, and 50% for normal glycemia, prediabetes, and new-onset diabetes, respectively (P < 0.001 for trend). The mean VPT was 6.5 V for normal glycemia, 7.9 V for prediabetes, and 7.6 V for new-onset diabetes (P = 0.024 for trend). Prediabetes was associated with higher MNSI scores (P = 0.01) and VPTs (P = 0.004) versus normal glycemia, independent of known risk factors. Additionally, progression of glucose intolerance over 3 years predicted a higher risk of peripheral neuropathy (P = 0.007) and nerve dysfunction (P = 0.002). Metabolic syndrome was not independently associated with MNSI scores or VPTs.

CONCLUSIONS

In individuals with multiple risk factors for diabetes, prediabetes was associated with similar risks of peripheral neuropathy and severity of nerve dysfunction as new-onset diabetes. Prediabetes, but not metabolic syndrome, was independently associated with both the presence of peripheral neuropathy and the severity of nerve dysfunction.

Impairments and comorbidities of polyneuropathy revealed by population-based analyses

OBJECTIVE

To quantify polyneuropathy impairments and comorbidities utilizing the Rochester Epidemiology Project (2010 census = 148,201).

METHODS

ICD-9-CM coding identified polyneuropathy cases (2006-2010) and their 5:1 age- and sex-matched controls. Mortality and impairments were evaluated while identifying and adjusting for Charlson Index comorbidities.

RESULTS

Overall prevalence of polyneuropathy was 1.66%, and markedly rose to 6.6% in persons older than 60 years. Cases (n = 2,892) had more comorbidities than controls (n = 14,435) with higher median Charlson Index (6 vs 3, p < 0.001). Diabetes with end-organ disease represented the largest increased comorbidity in cases compared with controls (46.8% vs 6.5%). Diabetic polyneuropathy was the most common specific subtype (38.2%). Miscoded idiopathic cases and false-negative controls also commonly had diabetic polyneuropathy. Median modified Rankin Scale score was considerably higher for cases than controls (4 vs 1, p < 0.001). Multiple comorbidities were found associated with polyneuropathy after adjusting for diabetes co-occurrence, including pulmonary disease, dementia, and others. Polyneuropathy was an independent contributor to multiple functional impairments including difficulty walking (odds ratio [OR] = 1.9), climbing stairs (OR = 2.0), using an assistive device (OR = 2.0), fall tendency (OR = 2.4), work disability (OR = 4.2), lower limb amputations (OR = 3.9), and opioid use (OR = 2.7). Prevalent cases had a younger median age at death than controls (80 vs 86 years, p < 0.001), and incident cases had a 6-month shorter survival.

CONCLUSIONS

Polyneuropathies have notable neurologic impairments beyond their identified multiple comorbidities. Life expectancy is shortened. Diabetic polyneuropathy is underidentified. The quantified extent of the disease burden and refined comorbidity associations emphasize that greater research efforts and health care initiatives are needed.