Improvement in Neuropathy Outcomes With Normalizing HbA1c in Patients With Type 2 Diabetes

Development and Progression of Polyneuropathy Over 5 Years in Patients With Type 2 Diabetes

BACKGROUND AND OBJECTIVES

There is a need for knowledge regarding the natural course of diabetic polyneuropathy (DPN), a complication in type 2 diabetes (T2D). The aim of this study was to examine the development of DPN over time.

METHODS

Patients with newly diagnosed T2D, recruited from a national cohort, and controls without diabetes of similar age and sex, underwent sensory phenotyping in 2016-2018. The Toronto consensus criteria were used to classify patients into possible, probable, and confirmed DPN. For this 5-year, observational, follow-up, cohort study, all participants were invited to a reexamination combining bedside sensory examination, quantitative sensory testing (QST), nerve conduction studies (NCSs), and skin biopsies measuring intraepidermal nerve fiber density (IENFD) in order to compare phenotypic and diagnostic changes over time.

RESULTS

Of the baseline 389 patients and 97 controls, 184 patients (median [interquartile range] diabetes duration 5.9 [4.1-7.4] years, mean hemoglobin A1c [HbA1c] 51 ± 11 mmol/mol at baseline) and 43 controls completed follow-up (46.9%). Confirmed DPN was present in 35.8% and 50.3%, probable DPN in 27.2% and 14.6%, possible DPN in 17.2% and 16.6%, and no DPN in 15.2% and 17.9% at baseline and follow-up, respectively. The estimated prevalence (95% CI) of confirmed DPN was 33.5% (24.9-42.1) compared with 22.7% (17.5-28.0) at baseline. During the follow-up period, 43.9% of patients with probable DPN developed confirmed DPN. Progression of neuropathy occurred in 16.5% and 24.7% and regression in 5.9% and 18.6% of patients based on NCS and IENFD, respectively. Progression based on NCS and/or IENFD was associated with higher baseline waist circumference and triglycerides, and regression with lower baseline HbA1c. Patients with at least probable DPN at baseline but neither patients without DPN nor controls developed increased spread of hyposensitivity, more hyposensitivity on QST and lower NCS z-scores at follow-up, and worsening of nerve parameters at follow-up correlated with higher baseline triglycerides.

DISCUSSION

In patients with well-regulated T2D, the proportion of patients with confirmed DPN increased over 5 years driven by progression from probable DPN. A large proportion of patients progressed, and a smaller proportion regressed on nerve parameters. Higher triglycerides correlated with this progression and may constitute a risk factor.

The effect of bariatric surgery on diabetes related foot complications among patients with type 2 diabetes: A systematic review

BACKGROUND

Bariatric surgery leads to considerable weight loss and improved glycaemic control and seems to have a favourable impact on diabetes related foot complications (DFC).

OBJECTIVES

To assess the effect of bariatric surgery on diabetes related foot complications in patients with type 2 diabetes and determine whether DFC symptoms are improved after bariatric surgery.

METHODS

We searched MEDLINE, Embase and Cochrane Central Register of Controlled Trials. The primary outcome was the presence of DFC after bariatric surgery. The secondary outcome was the improvement of DFC after bariatric surgery among patients who already had DFC before surgery.

RESULTS

There were nine studies showing the presence of DFC post bariatric surgery and six detailing the changes in DFC post bariatric surgery. Bariatric surgery was not associated with a lower risk of developing or worsening DFC compared to conventional medical treatment based on 4 randomised control trials (IR 0.87, 95 % CI, 0.26, 2.98), while from observational studies was associated with 51 % lower risk of DFC (IR 0.49, 95 % CI, 0.31, 0.77). Bariatric surgery was associated with improvement in diabetic neuropathy assessment parameters including toe tuning fork score, self-reported neuropathy symptoms, neuropathy symptom score, and neuropathy symptom profile.

CONCLUSION

Bariatric surgery led to a greater reduction in developing or worsening DFC among patients with type 2 diabetes compared to medical treatment in observational studies, but not among RCTs. Bariatric surgery was associated with improvements in diabetic neuropathy related assessment parameters and symptoms. Bariatric surgery could be a promising treatment for patients with type 2 diabetes who are at high risk of DFC.

Corneal confocal microscopy detects early nerve regeneration after pharmacological and surgical interventions: Systematic review and meta-analysis

Corneal confocal microscopy (CCM) is an ophthalmic imaging technique that enables the identification of corneal nerve fibre degeneration and regeneration. To undertake a systematic review and meta-analysis of studies utilizing CCM to assess for corneal nerve regeneration after pharmacological and surgical interventions in patients with peripheral neuropathy. Databases (EMBASE [Ovid], PubMed, CENTRAL and Web of Science) were searched to summarize the evidence from randomized and non-randomized studies using CCM to detect corneal nerve regeneration after pharmacological and surgical interventions. Data synthesis was undertaken using RevMan web. Eighteen studies including 958 patients were included. CCM identified an early (1-8 months) and longer term (1-5 years) increase in corneal nerve measures in patients with peripheral neuropathy after pharmacological and surgical interventions. This meta-analysis confirms the utility of CCM to identify nerve regeneration following pharmacological and surgical interventions. It could be utilized to show a benefit in clinical trials of disease modifying therapies for peripheral neuropathy.

Prevalence and Risk Factors of Distal Symmetric Polyneuropathy Among Predominantly Non-Hispanic Black, Low-Income Patients

BACKGROUND AND OBJECTIVES

Distal symmetric polyneuropathy (DSP) is a disabling, often painful condition associated with falls and reduced quality of life. Non-Hispanic Black people and people with low income are underrepresented in existing DSP studies; therefore, it is unknown whether data accurately reflect the prevalence, risk factors, and burden of disease in these populations.

METHODS

Patients older than 40 years presenting to an outpatient internal medicine clinic predominantly serving Medicaid patients in Flint, Michigan, were enrolled in a cross-sectional study. Demographics, clinical characteristics, including medication use, anthropomorphic measurements, fasting lipids, and hemoglobin A1c were collected. DSP was defined using the modified Toronto Clinical Neuropathy Score (mTCNS). Multivariable logistic regression was performed to model DSP and undiagnosed DSP as a function of potential risk factors age, metabolic syndrome, and race. DSP burden was measured using Peripheral Neuropathy Quality of Life Instrument-97.

RESULTS

Two hundred participants were enrolled, and 169 (85%) completed all data collection. The population was 55% female of mean age (SD) 58.2 years (10.4) and 69% non-Hispanic Black. Among the population, 50% had diabetes, 67% had metabolic syndrome, and 47% had a household income <$20,000. DSP was present in 73% of the population, of which 75% were previously undiagnosed. Neuropathic pain was documented in 57% of participants with DSP. DSP based on mTCNS criteria was associated with older age (odds ratio [OR] 1.1 [95% confidence interval (CI) 1.03-1.2]) and metabolic syndrome (OR 4.4 [1.1-18.1]). Non-Hispanic Black participants had lower odds of DSP (OR 0.1 [0.01-0.4]) than non-Hispanic White and Hispanic participants. DSP burden was high, including increased pain, health-related worry, and poorer quality of life (all p < 0.001).

DISCUSSION

DSP is extremely common and often underrecognized in this predominantly non-Hispanic Black, low-income population and leads to substantial disease burden. Metabolic syndrome is a highly prevalent, modifiable risk factor in this population that should be managed to lower DSP prevalence.

Diabetic Sensorimotor Polyneuropathy: An Overview on Epidemiology, Risk Factors, Classification, Diagnosis, and Treatment

Diabetic distal symmetric sensorimotor polyneuropathy (DSPN) is a common complication of diabetes with devastating consequences. Hyperglycaemia is the major aetiological factor, while emerging data demonstrate that cardiometabolic risk factors also contribute to its development. Diagnosis of DSPN involves interview of medical and neurological history, foot inspection, and sensory and motor function examination with specific tests such as temperature and pinprick perception for small nerve fibers, and vibration and light touch assessments for large nerve fibers. Management includes optimised glycaemic control, treatment of cardiovascular risk factors, and symptomatic treatment aiming at improving life quality. This article provides an overview on epidemiology, risk factors, classification, diagnosis and current treatment of DSPN.

Severity of Neuropathy-Related Disability and Associated Factors of Diabetic Peripheral Neuropathy in a Tertiary Healthcare Center: A Comparative Cross-Sectional Study

BACKGROUND AND OBJECTIVES

The widespread presence of diabetic peripheral neuropathy (DN) and its related variables among diagnosed diabetes mellitus (DM) patients in Kerala lacks sufficient evidence. The objective of this study was to evaluate the frequency of DN and its related risk variables among those with DM who were receiving care at a tertiary health institution in Kerala.

MATERIALS AND METHODS

This study was conducted in a tertiary health center in Kerala using a cross-sectional design. The diagnosis of diabetes was established by assessing the glycated hemoglobin A1c (HbA1c) level and the fasting blood glucose (FBG) level. A validated survey questionnaire was employed to gather demographic data as well as the medical history of DM and associated ailments. A thorough physical examination, BMI, and blood pressure were recorded. Dermatological, musculoskeletal, neurological, and vascular assessments were conducted. The subjects were assessed for neuropathy using a neuropathy disability score (NDS). Consequently, those who met the criteria for DM were classified into two groups: those with neuropathy and those without neuropathy. All research participants underwent laboratory examinations such as blood lipid profiles, HbA1c, and vitamin B12 complex concentrations.

RESULTS

The study included 200 DM patients; 120 men and 80 women. Study participants were 40-70 years old, with a median age of 53. The prevalence of DN significantly increased with age (p<0.001). The longer a patient had DM, the higher the prevalence of DN, and this variance in percentage was statistically significant (p<0.009) with an OR (odds ratio) of 9.246. A statistically significant 81 (40.5%) of participants graduated, compared to 119 (59.5%) with only higher secondary education or less (OR = 2.042; p = 0.014). Approximately 107 (53.5%) of individuals earned an income under two lakhs, and this disparity was deemed statistically significant (p = 0.003) with an OR of 2.357. In the group of individuals being studied, 53 (26.5%) of them experienced a decrease in pressure sensation, 47 (23.5%) had a decrease or absence of vibration perception, 48 (24%) had an absence or decreased pinprick response, and 46 (23%) had an absent ankle reflex. The study found that the most commonly reported symptoms were tingling (n = 44; 22%), numbness (n = 42; 21%), burning (n = 37; 18.5%), pricking (n = 29; 14.5%), and pain (n = 27; 13.5%). A strong association was found between DN and glycemic status, namely, FBG levels exceeding 140 mg/dL (OR = 4.511, p < 0.001) and HbA1c levels exceeding 6.5% (OR = 3.87, p < 0.001). The prevalence of abnormal vitamin B12 levels in individuals with DN was 63% (p = 0.19), indicating that the finding was not statistically significant. Within the group of individuals with DN being studied, 22% exhibited mild neuropathy, 34% displayed moderate neuropathy, and 44% had severe neuropathy. The DN individuals had significantly reduced ankle dorsiflexion in cases of severe NDS scores compared to those with mild to moderate NDS scores (p = 0.009). During the binary logistic regression analysis, it was shown that the duration of DM (OR = 1.73; p = 0.038) and FBG levels (OR = 2.87; p = 0.018) were determined as predictors for DN.

CONCLUSION

The findings of this study reveal that the duration of diabetes, age, literacy level, income, HbA1c, and FBG were substantially related to a higher likelihood of DN among diabetic patients.

A critical review on therapeutic approaches of CRISPR-Cas9 in diabetes mellitus

Diabetes mellitus (D.M.) is a common metabolic disorder caused mainly by combining two primary factors, which are (1) defects in insulin production by the pancreatic β-cells and (2) responsiveness of insulin-sensitive tissues towards insulin. Despite the rapid advancement in medicine to suppress elevated blood glucose levels (hyperglycemia) and insulin resistance associated with this hazard, a demand has undoubtedly emerged to find more effective and curative dimensions in therapeutic approaches against D.M. The administration of diabetes treatment that emphasizes insulin production and sensitivity may result in unfavorable side effects, reduced adherence, and potential treatment ineffectiveness. Recent progressions in genome editing technologies, for instance, in zinc-finger nucleases, transcription activator-like effector nucleases, and clustered regularly interspaced short palindromic repeat (CRISPR-Cas)-associated nucleases, have greatly influenced the gene editing technology from concepts to clinical practices. Improvements in genome editing technologies have also opened up the possibility to target and modify specific genome sequences in a cell directly. CRISPR/Cas9 has proven effective in utilizing ex vivo gene editing in embryonic stem cells and stem cells derived from patients. This application has facilitated the exploration of pancreatic beta-cell development and function. Furthermore, CRISPR/Cas9 enables the creation of innovative animal models for diabetes and assesses the effectiveness of different therapeutic strategies in treating the condition. We, therefore, present a critical review of the therapeutic approaches of the genome editing tool CRISPR-Cas9 in treating D.M., discussing the challenges and limitations of implementing this technology.

Assessment of the diagnostic accuracy of Vibrasense compared to a biothesiometer and nerve conduction study for screening diabetic peripheral neuropathy

AIMS

Peripheral neuropathy is a common microvascular complication in diabetes and a risk factor for the development of diabetic foot ulcers and amputations. Vibrasense (Ayati Devices) is a handheld, battery-operated, rapid screening device for diabetic peripheral neuropathy (DPN) that works by quantifying vibration perception threshold (VPT). In this study, we compared Vibrasense against a biothesiometer and nerve conduction study for screening DPN.

METHODS

A total of 562 subjects with type 2 diabetes mellitus underwent neuropathy assessments including clinical examination, 10-g monofilament test, VPT evaluation with Vibrasense and a standard biothesiometer. Those with an average VPT ≥ 15 V with Vibrasense were noted to have DPN. A subset of these patients (N = 61) underwent nerve conduction study (NCS). Diagnostic accuracy of Vibrasense was compared against a standard biothesiometer and abnormal NCS.

RESULTS

Average VPTs measured with Vibrasense had a strong positive correlation with standard biothesiometer values (Spearman's correlation 0.891, P < 0.001). Vibrasense showed sensitivity and specificity of 87.89% and 86.81% compared to biothesiometer, and 82.14% and 78.79% compared to NCS, respectively.

CONCLUSIONS

Vibrasense demonstrated good diagnostic accuracy for detecting peripheral neuropathy in type 2 diabetes and can be an effective screening device in routine clinical settings.

TRIAL REGISTRATION

Clinical trials registry of India (CTRI/2022/11/047002). Registered 3 November 2022.  https://ctri.nic.in/Clinicaltrials/pmaindet2.php?trialid=76167 .

Clinical Pathobiochemistry of Vitamin B12 Deficiency: Improving Our Understanding by Exploring Novel Mechanisms with a Focus on Diabetic Neuropathy

Vitamin B₁₂ (B₁₂) is an essential cofactor of two important biochemical pathways, the degradation of methylmalonic acid and the synthesis of methionine from homocysteine. Methionine is an important donor of methyl groups for numerous biochemical reactions, including DNA synthesis and gene regulation. Besides hematological abnormalities (megaloblastic anemia or even pancytopenia), a deficiency in B₁₂ may cause neurological symptoms, including symptoms resembling diabetic neuropathy. Although extensively studied, the underlining molecular mechanism for the development of diabetic peripheral neuropathy (DPN) is still unclear. Most studies have found a contribution of oxidative stress in the development of DPN. Detailed immunohistochemical investigations in sural nerve biopsies obtained from diabetic patients with DPN point to an activation of inflammatory pathways induced via elevated advanced glycation end products (AGE), ultimately resulting in increased oxidative stress. Similar results have been found in patients with B₁₂ deficiency, indicating that the observed neural changes in patients with DPN might be caused by cellular B₁₂ deficiency. Since novel results show that B₁₂ exerts intrinsic antioxidative activity in vitro and in vivo, B₁₂ may act as an intracellular, particularly as an intramitochondrial, antioxidant, independent from its classical, well-known cofactor function. These novel findings may provide a rationale for the use of B₁₂ for the treatment of DPN, even in subclinical early states.

Association of Elevated Serum Uric Acid with Nerve Conduction Function and Peripheral Neuropathy Stratified by Gender and Age in Type 2 Diabetes Patients

Background: The relationship between serum uric acid (SUA) level and diabetic peripheral neuropathy (DPN) remains controversial. We aimed to investigate the association between SUA level and DPN and evaluate the effects of SUA level on nerve conduction function via electromyography in patients with type 2 diabetes (T2DM), stratified by gender and age. Methods: This cross-sectional study included 647 inpatients with T2DM from the First Affiliated Hospital of Wenzhou Medical University between February 2017 and October 2020. The diagnosis of DPN was confirmed according to the Toronto Expert Consensus. Clinical data, SUA level, and nerve conduction parameters were obtained from electronic medical records. Results: A total of 647 patients with T2DM were included, and 471 patients were diagnosed with DPN. The level of SUA was higher in the DPN group than in the Non-DPN group (330.58 ± 99.67 vs. 309.16 ± 87.04, p < 0.05). After adjustment, a higher SUA level was associated with the presence of DPN [odds ratio (OR) 1.003, 95% confidence interval (CI), 1.001−1.005; p = 0.017]. The area under the curve for the prediction of DPN was 0.558 (95% CI, 0.509−0.608; p = 0.022), and the optimized cut-off of SUA level was 297.5 µmol/L. The SUA > 297.5 µmol/L level was independently associated with DPN in the male subgroup (OR 2.507, 95% CI, 1.405−4.473; p = 0.002) rather than in the female subgroup. Besides, SUA > 297.5 µmol/L was independently associated with DPN in the younger subgroup (age < 65 years) (OR 2.070, 95% CI, 1.278−3.352; p = 0.003) rather than in the older subgroup. In multiple linear regression analysis, SUA was significantly correlated with certain nerve conduction study parameters in the all patients group, and was also observed in the male and younger subgroups. Conclusions: Elevated SUA was independently associated with poorer nerve conduction functions, and hyperuricemia was also significantly associated with a higher risk of developing DPN in T2DM patients, especially in male and younger patients.

Retinal Neurodegeneration in Euglycemic Hyperinsulinemia, Prediabetes, and Diabetes

Diabetic retinopathy (DR) is a challenging public health problem mainly because of its growing prevalence and risk of blindness. In general, our current knowledge and practice have failed to prevent the onset or progression of DR to sight-threatening complications. While there are treatment options for sight-threatening complications of DR, it is crucial to pay more attention to the early stages of DR to decrease its prevalence. Growing evidence suggests many pathologic changes occur before clinical presentations of DR in euglycemic hyperinsulinemia, prediabetes, and diabetes. These pathological changes occur in retinal neurons, glia, and microvasculature. A new focus on these preclinical pathologies - especially on hyperinsulinemia - may provide further insight into disease mechanisms, endpoints for clinical trials, and druggable targets in early disease. Here, we review the current evidence on the pathophysiological changes reported in preclinical DR and appraise preventive and treatment options for DR.

Continuous glucose monitoring reveals a novel association between duration and severity of hypoglycemia, and small nerve fiber injury in patients with diabetes

Objective

Continuous glucose monitoring (CGM) has revealed that glycemic variability and low time in range are associated with albuminuria and retinopathy. We have investigated the relationship between glucose metrics derived from CGM and a highly sensitive measure of neuropathy using corneal confocal microscopy in participants with type 1 and type 2 diabetes.

Methods

A total of 40 participants with diabetes and 28 healthy controls underwent quantification of corneal nerve fiber density (CNFD), corneal nerve branch density (CNBD), corneal nerve fiber length (CNFL) and inferior whorl length (IWL) and those with diabetes underwent CGM for four consecutive days.

Results

CNBD was significantly lower in patients with high glycemic variability (GV) compared to low GV (median (range) (25.0 (19.0-37.5) vs 38.6 (29.2-46.9); P = 0.007); in patients who spent >4% compared to <4% time in level 1 hypoglycemia (54-69 mg/dL) (25.0 (22.9-37.5) vs 37.5 (29.2-46.9); P = 0.045) and in patients who spent >1% compared to <1% time in level 2 hypoglycemia (<54 mg/dL) (25.0 (19.8-41.7) vs 35.4 (28.1-44.8); P = 0.04). Duration in level 1 hypoglycemia correlated with CNBD (r = -0.342, P = 0.031). Duration in level 1 (181-250 mg/dL) and level 2 (>250 mg/dL) hyperglycemia did not correlate with CNFD (P > 0.05), CNBD (P > 0.05), CNFL (P > 0.05) or IWL (P > 0.05).

Conclusions

Greater GV and duration in hypoglycemia, rather than hyperglycemia, are associated with nerve fiber loss in diabetes.

A Nomogram for Predicting the Possibility of Peripheral Neuropathy in Patients with Type 2 Diabetes Mellitus

Background and Purpose: Diabetic peripheral neuropathy (DPN) leads to ulceration, noninvasive amputation, and long-term disability. This study aimed to develop and validate a nomogram for forecasting the probability of DPN in type 2 diabetes mellitus patients. Methods: From February 2017 to May 2021, 778 patients with type 2 diabetes mellitus were included in this study. We confirmed the diagnosis of DPN according to the Toronto Expert Consensus. Patients were randomly divided into a training cohort (n = 519) and a validation cohort (n = 259). In the training cohort, univariate and multivariate logistic regression analyses were performed, and a simple nomogram was built using the stepwise method. The receiver operating characteristic (ROC), calibration curve, and decision curve analysis were computed in order to validate the discrimination and clinical value of the nomogram model. Results: About 65.7% and 72.2% of patients were diagnosed with DPN in the training and validation cohorts. We developed a novel nomogram to predict the probability of DPN based on the parameters of age, gender, duration of diabetes, body mass index, uric acid, hemoglobin A1c, and free triiodothyronine. The areas under the curves (AUCs) of the nomogram model were 0.763 in the training cohort and 0.755 in the validation cohort. The calibration plots revealed well-fitted accuracy between the predicted and actual probability in the training and validation cohorts. Decision curve analysis confirmed the clinical value of the nomogram. In subgroup analysis, the predictive ability of the nomogram model was strong. Conclusions: The nomogram of age, gender, duration of diabetes, body mass index, uric acid, hemoglobin A1c, and free triiodothyronine may assist clinicians with the early identification of DPN in patients with type 2 diabetes mellitus.

Progressive loss of corneal nerve fibers is associated with physical inactivity and glucose lowering medication associated with weight gain in type 2 diabetes

Aims/Introduction

Limited studies have identified risk factors linked to the progression of diabetic peripheral neuropathy (DPN) in type 2 diabetes. This study examined the association of risk factors with change in neuropathy measures over 2 years.

Materials and Methods

Participants with type 2 diabetes (n = 78) and controls (n = 26) underwent assessment of clinical and metabolic parameters and neuropathy using corneal confocal microscopy (CCM), vibration perception threshold (VPT), and the DN4 questionnaire at baseline and 2 year follow‐up.

Results

Participants with type 2 diabetes had a lower corneal nerve fiber density (CNFD), branch density (CNBD), and fiber length (CNFL) (P ≤ 0.0001) and a higher VPT (P ≤ 0.01) compared with controls. Over 2 years, despite a modest reduction in HbA1c (P ≤ 0.001), body weight (P ≤ 0.05), and LDL (P ≤ 0.05) the prevalence of DPN (P = 0.28) and painful DPN (P = 0.21) did not change, but there was a significant further reduction in CNBD (P ≤ 0.0001) and CNFL (P ≤ 0.05). CNFD, CNBD, and CNFL decreased significantly in physically inactive subjects (P < 0.05–0.0001), whilst there was no change in CNFD (P = 0.07) or CNFL (P = 0.85) in physically active subjects. Furthermore, there was no change in CNFD (P = 0.82), CNBD (P = 0.08), or CNFL (P = 0.66) in patients treated with glucose lowering medication associated with weight loss, whilst CNBD (P = 0.001) decreased in patients on glucose lowering medication associated with weight gain.

Conclusions

In participants with type 2 diabetes, despite a modest improvement in HbA1c, body weight, and LDL there was a progressive loss of corneal nerve fibers; except in those who were physically active or on glucose lowering medication associated with weight loss.

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

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

Longitudinal effects of one-leg standing time on neuropathy outcomes in association with glycemic control in non-elderly patients with type 2 diabetes

Aims/Introduction

Diabetic neuropathy leads to postural instability. This study compared longitudinal changes in neuropathy outcomes relative to long‐term glycemic control in patients aged <60 years with uncontrolled type 2 diabetes with and without a short one‐leg standing time (OLST <60 s).

Materials and Methods

In this retrospective study, 58 hospitalized patients with type 2 diabetes (glycated hemoglobin [HbA1c] >7.0%; aged 17–59 years), who underwent re‐evaluation of neuropathic sensory symptoms, ankle reflexes and nerve conduction attributes, and cardiac autonomic function (R‐R interval), >1 year after discharge were divided into OLST <60 and ≥60 s groups. Patients were followed up every 2–3 months for HbA1c levels for up to 8 years. Neuropathy outcomes relative to OLST and HbA1c levels at baseline and over follow up were compared.

Results

Additional development of sensory symptoms (one patient) and abnormal ankle reflexes (five patients) were identified during follow up, and decreased peripheral and cardiac autonomic function at both baseline and follow up, only in patients with OLST <60 s. Mean HbA1c levels were significantly higher in patients with OLST <60 s versus ≥60 s (7.8 ± 0.9% vs 7.2 ± 1.2%; P = 0.022). Better glycemic control during follow up was associated with better neuropathy outcomes only in patients with OLST ≥60 s.

Conclusion

Non‐elderly type 2 diabetes patients with OLST <60 s and decreased peripheral nerve function at baseline are at increased risk for intractable diabetic neuropathy. Better glycemic control alone might not improve neuropathy outcomes in these patients.

Sodium Glucose Cotransporter-2 Inhibitor Protects Against Diabetic Neuropathy and Nephropathy in Modestly Controlled Type 2 Diabetes: Follow-Up Study

AIMS

This three-year follow-up study aimed to elucidate whether sodium-glucose cotransporter-2 inhibitors (SGLT2is) have any protection against diabetic neuropathy and nephropathy in patients with type 2 diabetes via reducing variability in glycemia and extraglycemic factors or their averages.

METHODS

Two type 2 diabetic cohorts of 40 and 73 patients treated with or without SGLT2i along with 60 control subjects were recruited. Two diabetic cohorts matched for HbA1c levels and oral hypoglycemic agents other than SGLT2is underwent glycemic control with or without SGLT2is more than two years. The urinary albumin to creatinine ratio (ACR), estimated glomerular filtration rate (eGFR) every 3 months and neuropathy outcome measures and mean Z-score of 8 neurophysiological tests were determined at the baseline and endpoint. Glycemic variability, evaluated by the coefficient of variation of monthly measured HbA1c levels and casual postprandial plasma glucose (CPPG), and coefficient of variation and average of extraglycemic parameters in diabetic cohorts were determined.

RESULTS

The glycemic variability and variability of some extraglycemic factors in SGLT2i cohort were smaller than those in non-SGLT2i cohort. However, only smaller coefficient of variation of HbA1c improved some neuropathy outcome measures, and ameliorated eGFR decline. SGLT2i improved the Z-score of neurophysiological tests. The optimized changes in the blood pressure, HDL-cholesterol and uric acid by SGLT2i led to neurological and renal protection. SGLT2i decreased the prevalence of nephropathy significantly and the prevalence of neuropathy insignificantly.

CONCLUSION

Over 3 years period, SGLT2i significantly improved some neuropathy outcome measures, mean Z-score of 8 neurophysiological tests, and attenuated nephropathy in modestly controlled type 2 diabetes by reducing glycemic variability and mean nonglycemic factors of diabetic microvascular complication.

Perspectives of glycemic variability in diabetic neuropathy: a comprehensive review

Diabetic neuropathy is one of the most prevalent chronic complications of diabetes, and up to half of diabetic patients will develop diabetic neuropathy during their disease course. Notably, emerging evidence suggests that glycemic variability is associated with the pathogenesis of diabetic complications and has emerged as a possible independent risk factor for diabetic neuropathy. In this review, we describe the commonly used metrics for evaluating glycemic variability in clinical practice and summarize the role and related mechanisms of glycemic variability in diabetic neuropathy, including cardiovascular autonomic neuropathy, diabetic peripheral neuropathy and cognitive impairment. In addition, we also address the potential pharmacological and non-pharmacological treatment methods for diabetic neuropathy, aiming to provide ideas for the treatment of diabetic neuropathy.

Zhang et al. describe metrics for evaluating glycaemic variability (GV) in clinical practice and summarize the role and related mechanisms of GV in diabetic neuropathy, including cardiovascular autonomic neuropathy, diabetic peripheral neuropathy and cognitive impairment. They aim to stimulate ideas for the treatment of diabetic neuropathy.

Management of diabetic neuropathy

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

Association of platelet count and plateletcrit with nerve conduction function and peripheral neuropathy in patients with type 2 diabetes mellitus

AIMS/INTRODUCTION

Diabetes has been considered as a 'pro-thrombotic state' with enhanced platelet reactivity. Abnormality in platelet aggregation has been found in patients with its most common chronic complication - diabetic peripheral neuropathy (DPN). The purpose of this study was to investigate the potential association of platelet indices with nerve conduction function and the presence of DPN in Chinese patients with type 2 diabetes mellitus.

MATERIALS AND METHODS

This study involved a total of 211 inpatients with type 2 diabetes mellitus and 55 healthy individuals for whom nerve conduction studies were carried out. DPN was diagnosed according to the American Diabetes Association recommendation. Clinical data were retrospectively collected.

RESULTS

Patients with diabetes in whom neuropathy developed had lower levels of platelet count (PLT) and plateletcrit (PCT) than healthy controls (P < 0.05). Statistically significant associations of low PLT and PCT levels with the reduction of summed amplitude/velocity Z-score, and the prolongation of F-wave minimum latency in nerve conduction studies were found. Furthermore, after multivariate adjustment, logistic regression analysis showed that low levels of PLT (odds ratio 2.268, 95% confidence interval 1.072-4.797; P < 0.05; PLT <226 vs PLT ≥226) and PCT (odds ratio 2.050, 95% confidence interval 1.001-4.201; P < 0.05; PCT <0.222 vs PCT ≥0.222) in type 2 diabetes mellitus patients were risk factors for the presence of DPN.

CONCLUSIONS

Lower PLT and PCT levels are closely associated with poorer peripheral nerve conduction functions and the presence of neuropathy in patients with type 2 diabetes mellitus, which suggests that PLT and PCT might be potential biomarkers for showing DPN.

Painful diabetic neuropathy is associated with increased nerve regeneration in patients with type 2 diabetes undergoing intensive glycemic control

AIMS/INTRODUCTION

Painful diabetic peripheral neuropathy (pDPN) is associated with small nerve fiber degeneration and regeneration. This study investigated whether the presence of pDPN might influence nerve regeneration in patients with type 2 diabetes undergoing intensive glycemic control.

MATERIALS AND METHODS

This exploratory substudy of an open-label randomized controlled trial undertook the Douleur Neuropathique en 4 questionnaire and assessment of electrochemical skin conductance, vibration perception threshold and corneal nerve morphology using corneal confocal microscopy in participants with and without pDPN treated with exenatide and pioglitazone or basal-bolus insulin at baseline and 1-year follow up, and 18 controls at baseline only.

RESULTS

Participants with type 2 diabetes, with (n = 13) and without (n = 28) pDPN had comparable corneal nerve fiber measures, electrochemical skin conductance and vibration perception threshold at baseline, and pDPN was not associated with the severity of DPN. There was a significant glycated hemoglobin reduction (P < 0.0001) and weight gain (P < 0.005), irrespective of therapy. Participants with pDPN showed a significant increase in corneal nerve fiber density (P < 0.05), length (P < 0.0001) and branch density (P < 0.005), and a decrease in the Douleur Neuropathique en 4 score (P < 0.01), but no change in electrochemical skin conductance or vibration perception threshold. Participants without pDPN showed a significant increase in corneal nerve branch density (P < 0.01) and no change in any other neuropathy measures. A change in the severity of painful symptoms was not associated with corneal nerve regeneration and medication for pain.

CONCLUSIONS

This study showed that intensive glycemic control is associated with greater corneal nerve regeneration and an improvement in the severity of pain in patients with painful diabetic neuropathy.

Using corneal confocal microscopy to compare Mecobalamin intramuscular injections vs oral tablets in treating diabetic peripheral neuropathy: a RCT

This randomized controlled study used corneal confocal microscopy (CCM) to compare the efficacy of Mecobalamin intramuscular injections vs oral tablets in treating mild to moderate diabetic peripheral neuropathy (DPN) by detecting early nerve fiber repair. Enrolled patients were randomized approximately 1:1 to receive Mecobalamin intramuscular injections (0.5 mg/day, 3 times/week) or Mecobalamin oral tablets (1.5 mg/day) for 8 weeks. Primary outcome was change of inferior whorl length (IWL) from baseline. Secondary outcomes included changes of corneal nerve fibre length (CNFL), corneal nerve fibre density (CNFD), corneal nerve branch density (CNBD) and the Survey of Autonomic Symptoms (SAS). 15 (93.75%) patients in the injection group and 17 (89.47%) patients in the tablet group completed the study. The injection treatment significantly improved patients' IWL from baseline (21.64 ± 3.00 mm/mm2 vs 17.64 ± 4.83 mm/mm2, P < 0.01) while the tablet treatment didn't. Additionally, the injection treatment led to significantly improved CNFL, CNBD and SAS from baseline (all P < 0.05) while the tablet treatment did not. No patient experienced any adverse events. In conclusion, CCM is sensitive enough to detect the superior efficacy of 8-week Mecobalamin intramuscular injection treatment for DPN compared to the oral tablet treatment.ClinicalTrials.gov registration number: NCT04372316 (30/04/2020).

Pathogenesis, diagnosis and clinical management of diabetic sensorimotor peripheral neuropathy

Diabetic sensorimotor peripheral neuropathy (DSPN) is a serious complication of diabetes mellitus and is associated with increased mortality, lower-limb amputations and distressing painful neuropathic symptoms (painful DSPN). Our understanding of the pathophysiology of the disease has largely been derived from animal models, which have identified key potential mechanisms. However, effective therapies in preclinical models have not translated into clinical trials and we have no universally accepted disease-modifying treatments. Moreover, the condition is generally diagnosed late when irreversible nerve damage has already taken place. Innovative point-of-care devices have great potential to enable the early diagnosis of DSPN when the condition might be more amenable to treatment. The management of painful DSPN remains less than optimal; however, studies suggest that a mechanism-based approach might offer an enhanced benefit in certain pain phenotypes. The management of patients with DSPN involves the control of individualized cardiometabolic targets, a multidisciplinary approach aimed at the prevention and management of foot complications, and the timely diagnosis and management of neuropathic pain. Here, we discuss the latest advances in the mechanisms of DSPN and painful DSPN, originating both from the periphery and the central nervous system, as well as the emerging diagnostics and treatments.

Corneal Confocal Microscopy: A Biomarker for Diabetic Peripheral Neuropathy

PURPOSE

Diagnosing early diabetic peripheral neuropathy remains a challenge due to deficiencies in currently advocated end points. The cornea is densely innervated with small sensory fibers, which are structurally and functionally comparable to intraepidermal nerve fibers. Corneal confocal microscopy is a method for rapid, noninvasive scanning of the living cornea with high resolution and magnification.

METHODS

This narrative review presents the framework for the development of biomarkers and the literature on the use and adoption of corneal confocal microscopy as an objective, diagnostic biomarker in experimental and clinical studies of diabetic peripheral neuropathy. A search was performed on PubMed and Google Scholar based on the terms "corneal confocal microscopy," "diabetic neuropathy," "corneal sensitivity," and "clinical trials."

FINDINGS

A substantial body of evidence underpins the thesis that corneal nerve loss predicts incident neuropathy and progresses with the severity of diabetic peripheral neuropathy. Corneal confocal microscopy also identifies early corneal nerve regeneration, strongly arguing for its inclusion as a surrogate end point in clinical trials of disease-modifying therapies.

IMPLICATIONS

There are sufficient diagnostic and prospective validation studies to fulfill the US Food and Drug Administration criteria for a biomarker to support the inclusion of corneal confocal microscopy as a primary end point in clinical trials of disease-modifying therapies in diabetic neuropathy.

Normative values of the vibration perception thresholds at finger pulps and metatarsal heads in healthy adults

AIMS

To establish normative values of vibration perception thresholds (VPTs), using multi-frequency vibrometry at finger pulps and at metatarsal heads of the foot in healthy adults. We also aimed to investigate factors that could potentially affect VPTs such as age, sex, height, weight, foot- or handedness and skin temperature.

METHODS

VPTs were examined in 924 healthy and randomly selected subjects in the southern Sweden (mean 46 years; 628 women and 296 men). Inclusion criterias were adult subjects (>18 years) in considerable health without diabetes mellitus or other nerve affecting disorders. VPTs were measured at the finger pulps of index and little finger, as well as the first and fifth metatarsal heads of the foot, through multi-frequency vibrometry using the VibroSense Meter® I device. Patient characteristics were recorded and skin temperature was measured before assessment of VPTs.

RESULTS

We present normative values of VPTs for a large population of both male and female subjects in various ages. VPTs detoriated as age increased (0.09-0.59 dB per year; p<0.001), i.e. progressing with normal aging. Increasing skin temperature affected VPTs in finger pulps, but not at metatarsal heads, with -0.2 to -1.6 dB, i.e. vibration perception improved with higher temperatures. Height was only found to affect the VPTs of metatarsal heads (250 Hz: 0.42 dB per cm). Sex, weight and handedness did not affect the VPTs.

CONCLUSION

We investigated the normative values of VPTs and presented affecting factors as age, skin temperature and height. With these results, VPT testing through multi-frequency vibrometry is enabled to be used in a clinical practice as a diagnostic tool when investigating neuropathy and other neurological disorders.

Diabetic neuropathy in children and youth: New and emerging risk factors

Pediatric neuropathy attributed to metabolic dysfunction is a well-known complication in children and youth with type 1 diabetes. Moreover, the rise of obesity and in particular of type 2 diabetes may cause an uptick in pediatric neuropathy incidence. However, despite the anticipated increase in neuropathy incidence, pathogenic insights and strategies to prevent or manage neuropathy in the setting of diabetes and obesity in children and youth remain unknown. Data from adult studies and available youth cohort studies are providing an initial understanding of potential diagnostic, management, and preventative measures in early life. This review discusses the current state of knowledge emanating from these efforts, with particular emphasis on the prevalence, clinical presentation, diagnostic approaches and considerations, and risk factors of neuropathy in type 1 and type 2 diabetes in children and youth. Also highlighted are current management strategies and recommendations for neuropathy in children and youth with diabetes. This knowledge, along with continued and sustained emphasis on identifying and eliminating modifiable risk factors, completing randomized controlled trials to assess effectiveness of strategies like weight loss and exercise, and enhancing awareness to support early detection and prevention, are pertinent to addressing the rising incidence of neuropathy associated with diabetes and obesity in children and youth.

Glycated Hemoglobin (HbA1c) as a Biomarker for Diabetic Foot Peripheral Neuropathy

BACKGROUND

Diabetic peripheral neuropathy (DPN) is known to predict foot ulceration, lower-extremity amputation and mortality. Patients with diabetes mellitus have a predisposition toward developing chronic inflammatory demyelinating polyneuropathy, and this may also facilitate the formation of diabetic foot and cutaneous impairment, which are considered one of the most serious impairments of diabetes mellitus, with a prevalence of 4-10% in this population. Biomarkers research provides opportunities for the early diagnosis of these complications for specific treatments useful to prevent amputation and, therefore, physical inability and mental disturbance. The recent literature has suggested that glycemic levels may be a novel factor in the pathogenesis of diabetic foot complications and is an important mediator of axonal dysfunction. The aim of this systematic literary review is to determine whether hemoglobin A1c (HbA1c) is a positive predictor for diabetic foot peripheral neuropathy and its complications, such as foot cutaneous impairments. There is a lack of consensus regarding the effect of glycemic variability on diabetic foot peripheral neuropathy, unlike other complications such as retinopathy, nephropathy or micro/macrovascular pathology Methods: Relevant articles were searched in the Medline database using PubMed and Scopus and relevant keywords. The primary search terms used were "glycated hemoglobin" OR "HbA1c" AND "diabetic neuropathies" AND "Foot".

RESULTS

A number of articles (336) were initially identified while searching the scientific literature regarding this topic, and 32 articles were selected and included in this review.

CONCLUSIONS

This review highlights the role of HbA1c in diabetic foot peripheral neuropathy. Biomarkers play an important role in the decision-making process, and HbA1c levels are extensively used for diabetic foot clinical outcomes and settings, but biomarker research in diabetic foot peripheral neuropathy is in its infancy and will require careful attention to a number of factors and associations, since the consequences of DPN also include neurological alterations. HbA1c is an accurate and easy-to-administer test and can be an effective biomarker in establishing the diagnosis of diabetes, but future research should focus on standardizing the HbA1c level and selecting which DPN value and its correlated complications, such as foot cutaneous impairments, are the most informative.

Vitamin B12 Supplementation in Diabetic Neuropathy: A 1-Year, Randomized, Double-Blind, Placebo-Controlled Trial

AIM

To investigate the effect of normalizing vitamin B12 (B12) levels with oral B12 (methylcobalamin) 1000 μg/day for one year in patients with diabetic neuropathy (DN).

PATIENTS AND METHODS

In this prospective, double-blind, placebo-controlled trial, 90 patients with type 2 diabetes on metformin for at least four years and both peripheral and autonomic DN were randomized to an active treatment group (n = 44) receiving B12 and a control group (n = 46) receiving a placebo. All patients had B12 levels less than 400 pmol/L. Subjects underwent measurements of sural nerve conduction velocity (SNCV), sural nerve action potential (amplitude) (SNAP), and vibration perception threshold (VPT), and they performed cardiovascular autonomic reflex tests (CARTs: mean circular resultant (MCR), Valsalva test, postural index, and orthostatic hypotension). Sudomotor function was assessed with the SUDOSCAN that measures electrochemical skin conductance in hands and feet (ESCH and ESCF, respectively). We also used the Michigan Neuropathy Screening Instrument Questionnaire and Examination (MNSIQ and MNSIE, respectively) and questionnaires to evaluate quality of life (QoL) and level of pain (pain score).

RESULTS

B12 levels increased from 232.0 ± 71.8 at baseline to 776.7 ± 242.3 pmol/L at follow-up, p < 0.0001, in the active group but not in the control group. VPT, MNSIQ, QoL, pain score, SNCV, SNAP, and ESCF significantly improved in the active group (p < 0.001, p = 0.002, p < 0.0001, p < 0.000, p < 0.0001, p < 0.0001, and p = 0.014, respectively), whereas CARTS and MNSIE improved but not significantly. MCR, MNSIQ, SNCV, SNAP, and pain score significantly deteriorated in the control group (p = 0.025, p = 0.017, p = 0.045, p < 0.0001, and p < 0.0001, respectively).

CONCLUSIONS

The treatment of patients with DN with 1 mg of oral methylcobalamin for twelve months increased plasma B12 levels and improved all neurophysiological parameters, sudomotor function, pain score, and QoL, but it did not improve CARTS and MNSIE.

Corneal confocal microscopy identifies small fibre damage and progression of diabetic neuropathy

Accurately quantifying the progression of diabetic peripheral neuropathy is key to identify individuals who will progress to foot ulceration and to power clinical intervention trials. We have undertaken detailed neuropathy phenotyping to assess the longitudinal utility of different measures of neuropathy in patients with diabetes. Nineteen patients with diabetes (age 52.5 ± 14.7 years, duration of diabetes 26.0 ± 13.8 years) and 19 healthy controls underwent assessment of symptoms and signs of neuropathy, quantitative sensory testing, autonomic nerve function, neurophysiology, intra-epidermal nerve fibre density (IENFD) and corneal confocal microscopy (CCM) to quantify corneal nerve fibre density (CNFD), branch density (CNBD) and fibre length (CNFL). Mean follow-up was 6.5 years. Glycated haemoglobin (p = 0.04), low-density lipoprotein-cholesterol (LDL-C) (p = 0.0009) and urinary albumin creatinine ratio (p < 0.0001) improved. Neuropathy symptom profile (p = 0.03), neuropathy disability score (p = 0.04), vibration perception threshold (p = 0.02), cold perception threshold (p = 0.006), CNFD (p = 0.03), CNBD (p < 0.0001), CNFL (p < 0.0001), IENFD (p = 0.04), sural (p = 0.02) and peroneal motor nerve conduction velocity (p = 0.03) deteriorated significantly. Change (∆) in CNFL correlated with ∆CPT (p = 0.006) and ∆Expiration/Inspiration ratio (p = 0.002) and ∆IENFD correlated with ∆CNFD (p = 0.005), ∆CNBD (p = 0.02) and ∆CNFL (p = 0.01). This study shows worsening of diabetic neuropathy across a range of neuropathy measures, especially CCM, despite an improvement in HbA1c and LDL-C. It further supports the utility of CCM as a rapid, non-invasive surrogate measure of diabetic neuropathy.

Diagnosis of Neuropathy and Risk Factors for Corneal Nerve Loss in Type 1 and Type 2 Diabetes: A Corneal Confocal Microscopy Study

OBJECTIVE

To assess the diagnostic utility of corneal confocal microscopy (CCM) for diabetic peripheral neuropathy (DPN) and the risk factors for corneal nerve loss.

RESEARCH DESIGN AND METHODS

A total of 490 participants, including 72 healthy control subjects, 149 with type 1 diabetes, and 269 with type 2 diabetes, underwent detailed assessment of peripheral neuropathy and CCM in relation to risk factors.

RESULTS

Corneal nerve fiber density (CNFD) (P < 0.0001 and P < 0.0001), corneal nerve fiber branch density (CNBD) (P < 0.0001 and P < 0.0001), and corneal nerve fiber length (CNFL) (P < 0.0001 and P = 0.02) were significantly lower in patients with type 1 and type 2 diabetes compared with control subjects. CNFD (P < 0.0001), CNBD (P < 0.0001), and CNFL (P < 0.0001) were lower in type 1 diabetes compared with type 2 diabetes. Receiver operating characteristic curve analysis for the diagnosis of DPN demonstrated a good area under the curve for CNFD of 0.81, CNBD of 0.74, and CNFL of 0.73. Multivariable regression analysis showed a significant association among reduced CNFL with age (β = -0.27, P = 0.007), HbA_1c (β = -1.1; P = 0.01), and weight (β = -0.14; P = 0.03) in patients with type 2 diabetes and with duration of diabetes (β = -0.13; P = 0.02), LDL cholesterol (β = 1.8, P = 0.04), and triglycerides (β = -2.87; P = 0.009) in patients with type 1 diabetes.

CONCLUSIONS

CCM identifies more severe corneal nerve loss in patients with type 1 diabetes compared with type 2 diabetes and shows good diagnostic accuracy for DPN. Furthermore, the risk factors for a reduction in corneal nerve fiber length differ between type 1 and type 2 diabetes.

The Impact of Glycemic Control on Retinal Photoreceptor Layers and Retinal Pigment Epithelium in Patients With Type 2 Diabetes Without Diabetic Retinopathy: A Follow-Up Study

AIMS

To establish the sequential changes by glycemic control in the mean thickness, volume and reflectance of the macular photoreceptor layers (MPRLs) and retinal pigment epithelium in patients with type 2 diabetes without diabetic retinopathy.

METHODS

Thirty-one poorly controlled (HbA1c > 8.0%) patients with type 2 diabetes without diabetic retinopathy undergoing glycemic control and 39 control subjects with normal HbA1c levels (< 5.9%) underwent periodical full medical, neurological and ophthalmological examinations over 2 years. Glycemic variability was evaluated by standard deviation and coefficient of variation of monthly measured HbA1c levels and casual plasma glucose. 3D swept source-optical coherence tomography (OCT) and OCT-Explorer-generated enface thickness, volume and reflectance images for 9 subfields defined by Early Treatment Diabetic Retinopathy Study of 4 MPRLs {outer nuclear layer, ellipsoid zone, photoreceptor outer segment (PROS) and interdigitation zone} and retinal pigment epithelium were acquired every 3 months.

RESULTS

Glycemic control sequentially restored the thickness and volume at 6, 4 and 5 subfields of outer nuclear layer, ellipsoid zone and PROS, respectively. The thickness and volume of outer nuclear layer were restored related to the decrease in HbA1c and casual plasma glucose levels, but not related to glycemic variability and neurological tests. The reflectance of MPRLs and retinal pigment epithelium in patients was marginally weaker than controls, and further decreased at 6 or 15 months during glycemic control. The reduction at 6 months coincided with high HbA1c levels.

CONCLUSION

Glycemic control sequentially restored the some MPRL thickness, especially of outer nuclear layer. In contrast, high glucose during glycemic control decreased reflectance and may lead to the development of diabetic retinopathy induced by glycemic control. The repeated OCT examinations can clarify the benefit and hazard of glycemic control to the diabetic retinopathy.

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.

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

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

Lipopolysaccharide-binding protein is a distinctive biomarker of abnormal pain threshold in the general Japanese population

INTRODUCTION

Small fiber neuropathy (SFN) is an early manifestation in diabetic polyneuropathy (DPN); however, the mechanisms are not fully understood. In diabetes, SFN is presumed to be common in individuals with overt DPN, enhancing activation of polyol pathway, oxidative stress, advanced glycation end products (AGEs), and inflammation. We explored the relationship between clinicohematological factors related to DPN and pain sensation in the Japanese population.

RESEARCH DESIGN AND METHODS

We conducted a population-based study, recruiting 1030 individuals (average age 54.4±0.5 years), in 2017, to participate in our Iwaki project. After initial screening by fasting blood glucose and glycohemoglobin A1c (HbA1c) measurements, the subjects were categorized into control (n=894), type 2 diabetes (n=81), and impaired fasting glucose (n=55) groups. Clinical data were gathered, and relationships between pain threshold from intraepidermal electrical stimulation (PINT) and DPN were examined by analysis of variance, post hoc test, and χ² tests to study correlations among and between groups of the clinical data and DPN.

RESULTS

Univariate linear regression analyses showed significant correlations between PINT and serum lipopolysaccharide-binding protein (LBP) level (ß=0.1025, p=0.001). Adjustments for the clinical measurements confirmed a positive correlation (ß=0.070, p=0.034). Logistic regression analysis revealed high LBP value (>6.7 mg/dL) as a significant risk factor toward abnormal PINT (≥0.35 mA). LBP significantly correlated with the high-sensitivity C reactive protein, inflammation marker, elevated similarly in both pre-diabetic and overt-diabetic groups, compared with controls, but it did not correlate with a decreased Achilles tendon reflex. In contrast, urine 8-hydroxy-2'-deoxyguanosine, oxidative stress marker, and pentosidine, AGEs, markedly increased in individuals with type 2 diabetes with high HbA1c.

CONCLUSIONS

Individuals with high LBP exhibited an elevated PINT in the Japanese population. Low level of inflammation evoked by metabolic endotoxemia is possibly implicated in the pathophysiology of SFN from pre-diabetic stage.

Corneal nerve loss in children with type 1 diabetes mellitus without retinopathy or microalbuminuria

Aims/Introduction

Corneal confocal microscopy is a rapid, non‐invasive ophthalmic technique to identify subclinical neuropathy. The aim of this study was to quantify corneal nerve morphology in children with type 1 diabetes mellitus compared with age‐matched healthy controls using corneal confocal microscopy.

Materials and Methods

A total of 20 participants with type 1 diabetes mellitus (age 14 ± 2 years, diabetes duration 4.08 ± 2.91 years, glycated hemoglobin 9.3 ± 2.1%) without retinopathy or microalbuminuria and 20 healthy controls were recruited from outpatient clinics. Corneal confocal microscopy was undertaken, and corneal nerve fiber density (n/mm²), corneal nerve branch density (n/mm²), corneal nerve fiber length (mm/mm²), corneal nerve fiber tortuosity and inferior whorl length (mm/mm²) were quantified manually.

Results

Corneal nerve fiber density (22.73 ± 8.84 vs 32.92 ± 8.59; P < 0.001), corneal nerve branch density (26.19 ± 14.64 vs 47.34 ± 20.01; P < 0.001), corneal nerve fiber length (13.26 ± 4.06 vs 19.52 ± 4.54; P < 0.001) and inferior whorl length (15.50 ± 5.48 vs 23.42 ± 3.94; P < 0.0001) were significantly lower, whereas corneal nerve fiber tortuosity (14.88 ± 5.28 vs 13.52 ± 3.01; P = 0.323) did not differ between children with type 1 diabetes mellitus and controls. Glycated hemoglobin correlated with corneal nerve fiber tortuosity (P < 0.006) and aspartate aminotransferase correlated with corneal nerve fiber density (P = 0.039), corneal nerve branch density (P = 0.003) and corneal nerve fiber length (P = 0.037).

Conclusion

Corneal confocal microscopy identifies significant subclinical corneal nerve loss, especially in the inferior whorl of children with type 1 diabetes mellitus without retinopathy or microalbuminuria.

Effect of treatment with exenatide and pioglitazone or basal-bolus insulin on diabetic neuropathy: a substudy of the Qatar Study

INTRODUCTION

To assess the effect of exenatide and pioglitazone or basal-bolus insulin on diabetic peripheral neuropathy (DPN) in patients with poorly controlled type 2 diabetes (T2D).

RESEARCH DESIGN AND METHODS

This is a substudy of the Qatar Study, an open-label, randomized controlled trial. 38 subjects with poorly controlled T2D were studied at baseline and 1-year follow-up and 18 control subjects were assessed at baseline only. A combination of exenatide (2 mg/week) and pioglitazone (30 mg/day) or glargine with aspart insulin were randomly assigned to patients to achieve an HbA1c <53 mmol/mol (<7%). DPN was assessed with corneal confocal microscopy (CCM), DN4, vibration perception and sudomotor function.

RESULTS

Subjects with T2D had reduced corneal nerves, but other DPN measures were comparable with the control group. In the combination treatment arm (n=21), HbA1c decreased by 35.2 mmol/mol (3.8 %) (p<0.0001), body weight increased by 5.6 kg (p<0.0001), corneal nerve branch density increased (p<0.05), vibration perception worsened (p<0.05), and DN4 and sudomotor function showed no change. In the insulin treatment arm, HbA1c decreased by 28.7 mmol/mol (2.7 %) (p<0.0001), body weight increased by 4.6 kg (p<0.01), corneal nerve branch density and fiber length increased (p≤0.01), vibration perception improved (p<0.01), and DN4 and sudomotor function showed no change. There was no association between the change in CCM measures with change in HbA1c, weight or lipids.

CONCLUSIONS

Treatment with exenatide and pioglitazone or basal-bolus insulin results in corneal nerve regeneration, but no change in neuropathic symptoms or sudomotor function over 1 year.

Improved metabolic control using glucose monitoring systems leads to improvement in vibration perception thresholds in type 1 diabetes patients

AIMS

Few studies have examined how improved metabolic control might influence vibration perception thresholds (VPTs). The aim of this study was to evaluate if improved HbA_1c can influence vibration thresholds in adults with type 1 diabetes (T1DM).

METHODS

VPTs were investigated at six frequencies (4-125 Hz) using VibroSense Meter in the sole of the foot at two occasions in 159 T1DM patients, at the heads of the first and fifth metatarsal bones, i.e. MTH1 and MTH5, respectively. The participants were divided into three groups: group A: HbA_1c improved by more than 1 mmol/mol (n = 95), group B: HbA_1c deteriorated by more than 1 mmol/mol (n = 48) and group C: HbA_1c unchanged (± 1 mmol/mol) (n = 16) compared to baseline.

RESULTS

In group A, the mean z-score, reflecting the combined effect of all VPTs, improved being lower at the follow-up than at the baseline [0.2 (- 0.3 to 1.2) vs. -0.1 (- 0.7 to 0.8), p = 0.00002]. VPTs improved at 4 and 64 Hz at both MTH1 (metatarsal head 1) and MTH5. The VPTs at 125 Hz frequency improved at MTH5, but not at MTH1. No significant differences were seen in group B or group C.

CONCLUSIONS

Lower HbA_1c and lower VPTs in T1DM patients were associated with improved VPT, suggesting a reversible effect on nerve function by improved metabolic control.

Lumos for the long trail: Strategies for clinical diagnosis and severity staging for diabetic polyneuropathy and future directions

Diabetic polyneuropathy, which is a chronic symmetrical length-dependent sensorimotor polyneuropathy, is the most common form of diabetic neuropathy. Although diabetic polyneuropathy is the most important risk factor in cases of diabetic foot, given its poor prognosis, the criteria for diagnosis and staging of diabetic polyneuropathy has not been established; consequently, no disease-modifying treatment is available. Most criteria and scoring systems that were previously proposed consist of clinical signs, symptoms and quantitative examinations, including sensory function tests and nerve conduction study. However, in diabetic polyneuropathy, clinical symptoms, including numbness, pain and allodynia, show no significant correlation with the development of pathophysiological changes in the peripheral nervous system. Therefore, these proposed criteria and scoring systems have failed to become a universal clinical end-point for large-scale clinical trials evaluating the prognosis in diabetes patients. We should use quantitative examinations of which validity has been proven. Nerve conduction study, for example, has been proven effective to evaluate dysfunctions of large nerve fibers. Baba's classification, which uses a nerve conduction study, is one of the most promising diagnostic methods. Loss of small nerve fibers can be determined using corneal confocal microscopy and intra-epidermal nerve fiber density. However, no staging criteria have been proposed using these quantitative evaluations for small fiber neuropathy. To establish a novel diagnostic and staging criteria of diabetic polyneuropathy, we propose three principles to be considered: (i) include only generalizable objective quantitative tests; (ii) exclude clinical symptoms and signs; and (iii) do not restrictively exclude other causes of polyneuropathy.

Insulin Treatment Attenuates Small Nerve Fiber Damage in Rat Model of Type 2 Diabetes

INTRODUCTION

Current clinical guidelines for management of diabetic peripheral neuropathy (DPN) emphasize good glycemic control. However, this has limited effect on prevention of DPN in type 2 diabetic (T2D) patients. This study investigates the effect of insulin treatment on development of DPN in a rat model of T2D to assess the underlying causes leading to DPN.

METHODS

Twelve-week-old male Sprague-Dawley rats were allocated to a normal chow diet or a 45% kcal high-fat diet. After eight weeks, the high-fat fed animals received a mild dose of streptozotocin to induce hyperglycemia. Four weeks after diabetes induction, the diabetic animals were allocated into three treatment groups receiving either no insulin or insulin-releasing implants in a high or low dose. During the 12-week treatment period, blood glucose and body weight were monitored weekly, whereas Hargreaves' test was performed four, eight, and 12 weeks after treatment initiation. At study termination, several blood parameters, body composition, and neuropathy endpoints were assessed.

RESULTS

Insulin treatment lowered blood glucose in a dose-dependent manner. In addition, both doses of insulin lowered lipids and increased body fat percentage. High-dose insulin treatment attenuated small nerve fiber damage assessed by Hargreaves' test and intraepidermal nerve fiber density compared to untreated diabetes and low-dose insulin; however, neuropathy was not completely prevented by tight glycemic control. Linear regression analysis revealed that glycemic status, circulating lipids, and sciatic nerve sorbitol level were all negatively associated with the small nerve fiber damage observed.

CONCLUSION

In summary, our data suggest that high-dose insulin treatment attenuates small nerve fiber damage. Furthermore, data also indicate that both poor glycemic control and dyslipidemia are associated with disease progression. Consequently, this rat model of T2D seems to fit well with progression of DPN in humans and could be a relevant preclinical model to use in relation to research investigating treatment opportunities for DPN.

Diabetic neuropathy

The global epidemic of prediabetes and diabetes has led to a corresponding epidemic of complications of these disorders. The most prevalent complication is neuropathy, of which distal symmetric polyneuropathy (for the purpose of this Primer, referred to as diabetic neuropathy) is very common. Diabetic neuropathy is a loss of sensory function beginning distally in the lower extremities that is also characterized by pain and substantial morbidity. Over time, at least 50% of individuals with diabetes develop diabetic neuropathy. Glucose control effectively halts the progression of diabetic neuropathy in patients with type 1 diabetes mellitus, but the effects are more modest in those with type 2 diabetes mellitus. These findings have led to new efforts to understand the aetiology of diabetic neuropathy, along with new 2017 recommendations on approaches to prevent and treat this disorder that are specific for each type of diabetes. In parallel, new guidelines for the treatment of painful diabetic neuropathy using distinct classes of drugs, with an emphasis on avoiding opioid use, have been issued. Although our understanding of the complexities of diabetic neuropathy has substantially evolved over the past decade, the distinct mechanisms underlying neuropathy in type 1 and type 2 diabetes remains unknown. Future discoveries on disease pathogenesis will be crucial to successfully address all aspects of diabetic neuropathy, from prevention to treatment.

Diabetic neuropathy

The global epidemic of prediabetes and diabetes has led to a corresponding epidemic of complications of these disorders. The most prevalent complication is neuropathy, of which distal symmetric polyneuropathy (for the purpose of this Primer, referred to as diabetic neuropathy) is very common. Diabetic neuropathy is a loss of sensory function beginning distally in the lower extremities that is also characterized by pain and substantial morbidity. Over time, at least 50% of individuals with diabetes develop diabetic neuropathy. Glucose control effectively halts the progression of diabetic neuropathy in patients with type 1 diabetes mellitus, but the effects are more modest in those with type 2 diabetes mellitus. These findings have led to new efforts to understand the aetiology of diabetic neuropathy, along with new 2017 recommendations on approaches to prevent and treat this disorder that are specific for each type of diabetes. In parallel, new guidelines for the treatment of painful diabetic neuropathy using distinct classes of drugs, with an emphasis on avoiding opioid use, have been issued. Although our understanding of the complexities of diabetic neuropathy has substantially evolved over the past decade, the distinct mechanisms underlying neuropathy in type 1 and type 2 diabetes remains unknown. Future discoveries on disease pathogenesis will be crucial to successfully address all aspects of diabetic neuropathy, from prevention to treatment.

Diagnosing and managing diabetic somatic and autonomic neuropathy

The diagnosis and management of diabetic neuropathy can be a major challenge. Late diagnosis contributes to significant morbidity in the form of painful diabetic neuropathy, foot ulceration, amputation, and increased mortality. Both hyperglycaemia and cardiovascular risk factors are implicated in the development of somatic and autonomic neuropathy and an improvement in these risk factors can reduce their rate of development and progression. There are currently no US Food and Drug Administration (FDA)-approved disease-modifying treatments for either somatic or autonomic neuropathy, as a consequence of multiple failed phase III clinical trials. While this may be partly attributed to premature translation, there are major shortcomings in trial design and outcome measures. There are a limited number of partially effective FDA-approved treatments for the symptomatic relief of painful diabetic neuropathy and autonomic neuropathy.