Modeling chronic glycemic exposure variables as correlates and predictors of microvascular complications of diabetes

Morphometry of the sural nerve in diabetic neuropathy: a systematic review

PURPOSE

The aim of this systematic review is to evaluate the usefulness of sural nerve ultrasonography in diagnosing diabetes mellitus (DM) and diabetic polyneuropathy (DPN), the latter of which is a common long-term complication for diabetic patients that frequently involves the sural nerve.

METHODOLOGY

A meta-analysis of the cross-sectional areas (CSAs) of sural nerves in healthy individuals and patients with diabetes mellitus based on a total of 32 ultrasonographic-based studies from 2015 to 2023 was performed. Sub-analyses were performed for factors such as geographical location and measurement site.

RESULTS

The meta-analysis showed that the mean CSA of the sural nerve was significantly larger in DM patients with DPN only compared to healthy individuals across all regions and when pooled together. An age-dependent increase in the CSA of healthy sural nerves is apparent when comparing the paediatric population with adults.

CONCLUSION

Sural nerve ultrasonography can distinguish diabetic adults with DPN from healthy adults based on cross-sectional area measurement. Future studies are needed to clarify the relationships between other parameters, such as body metrics and age, with sural nerve CSAs. Cut-offs for DPN likely need to be specific for different geographical regions.

Association of systemic immune-inflammation index with diabetic kidney disease in patients with type 2 diabetes: a cross-sectional study in Chinese population

Objective

Systemic immune-inflammation index (SII), a novel inflammatory marker, has been reported to be associated with diabetic kidney disease (DKD) in the U.S., however, such a close relationship with DKD in other countries, including China, has not been never determined. We aimed to explore the association between SII and DKD in Chinese population.

Methods

A total of 1922 hospitalized patients with type 2 diabetes mellitus (T2DM) included in this cross-sectional study were divided into three groups based on estimated glomerular filtration rate (eGFR) and urinary albumin-to-creatinine ratio (ACR): non-DKD group, DKD stages 1-2 Alb group, and DKD-non-Alb+DKD stage 3 Alb group. The possible association of SII with DKD was investigated by correlation and multivariate logistic regression analysis, and receiver-operating characteristic (ROC) curves analysis.

Results

Moving from the non-DKD group to the DKD-non-Alb+DKD stage 3 Alb group, SII level was gradually increased (P for trend <0.01). Partial correlation analysis revealed that SII was positively associated with urinary ACR and prevalence of DKD, and negatively with eGFR (all P<0.01). Multivariate logistic regression analysis showed that SII remained independently significantly associated with the presence of DKD after adjustment for all confounding factors [(odds ratio (OR), 2.735; 95% confidence interval (CI), 1.840-4.063; P < 0.01)]. Moreover, compared with subjects in the lowest quartile of SII (Q1), the fully adjusted OR for presence of DKD was 1.060 (95% CI 0.773-1.455) in Q2, 1.167 (95% CI 0.995-1.368) in Q3, 1.266 (95% CI 1.129-1.420) in the highest quartile (Q4) (P for trend <0.01). Similar results were observed in presence of DKD stages 1-2 Alb or presence of DKD-non- Alb+DKD stage 3 Alb among SII quartiles. Last, the analysis of ROC curves revealed that the best cutoff values for SII to predict DKD, Alb DKD stages 1- 2, and DKD-non-Alb+ DKD stage 3 Alb were 609.85 (sensitivity: 48.3%; specificity: 72.8%), 601.71 (sensitivity: 43.9%; specificity: 72.3%), and 589.27 (sensitivity: 61.1%; specificity: 71.1%), respectively.

Conclusion

Higher SII is independently associated with an increased risk of the presence and severity of DKD, and SII might be a promising biomarker for DKD and its distinct phenotypes in Chinese population.

Cumulative HbA1c exposure as a CVD risk in patients with type 2 diabetes: A post hoc analysis of ACCORD trial

AIMS

The study aimed to investigate the relationship between cumulative HbA1c exposure and cardiovascular events in patients with type 2 diabetes (T2D).

METHODS

This study included 9307 participants from the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial. Cumulative HbA1c exposure was calculated as the area under the curve during exposure time.

RESULTS

After adjusting for covariates, a 1-SD increase in cumulative HbA1c exposure was significantly associated with a higher risk of the primary outcome (HR 1.32, 95 % CI: 1.22-1.43, P < 0.001), all-cause mortality (HR 1.33, 95 % CI: 1.21-1.46, P < 0.001), and cardiovascular death (HR 1.45, 95 % CI: 1.27-1.67, P < 0.001). These associations were independent of baseline HbA1c and the first HbA1c level after enrollment. Cross-tabulation analysis showed that participants in the intensive-therapy group with high baseline HbA1c and cumulative HbA1c exposure had a significantly higher risk of primary outcome, all-cause mortality and cardiovascular death.

CONCLUSIONS

Higher cumulative HbA1c exposure was significantly associated with an increased risk of the primary outcome, all-cause mortality and cardiovascular death among T2D patients. Patients with T2D should strive for stable glycemic control to reduce their risk of cardiovascular events, and that those with high baseline HbA1c may require more intensive therapy to achieve this goal.

Recent updates in the treatment of diabetic polyneuropathy

Distal symmetric diabetic peripheral polyneuropathy (DPN) is the most common form of neuropathy in the world, affecting 30 to 50% of diabetic individuals and resulting in significant morbidity and socioeconomic costs. This review summarizes updates in the diagnosis and management of DPN. Recently updated clinical criteria facilitate bedside diagnosis, and a number of new technologies are being explored for diagnostic confirmation in specific settings and for use as surrogate measures in clinical trials. Evolving literature indicates that distinct but overlapping mechanisms underlie neuropathy in type 1 versus type 2 diabetes, and there is a growing focus on the role of metabolic factors in the development and progression of DPN. Exercise-based lifestyle interventions have shown therapeutic promise. A variety of potential disease-modifying and symptomatic therapies are in development. Innovations in clinical trial design include the incorporation of detailed pain phenotyping and biomarkers for central sensitization.

American Association of Clinical Endocrinology Clinical Practice Guideline: Developing a Diabetes Mellitus Comprehensive Care Plan-2022 Update

OBJECTIVE

The objective of this clinical practice guideline is to provide updated and new evidence-based recommendations for the comprehensive care of persons with diabetes mellitus to clinicians, diabetes-care teams, other health care professionals and stakeholders, and individuals with diabetes and their caregivers.

METHODS

The American Association of Clinical Endocrinology selected a task force of medical experts and staff who updated and assessed clinical questions and recommendations from the prior 2015 version of this guideline and conducted literature searches for relevant scientific papers published from January 1, 2015, through May 15, 2022. Selected studies from results of literature searches composed the evidence base to update 2015 recommendations as well as to develop new recommendations based on review of clinical evidence, current practice, expertise, and consensus, according to established American Association of Clinical Endocrinology protocol for guideline development.

RESULTS

This guideline includes 170 updated and new evidence-based clinical practice recommendations for the comprehensive care of persons with diabetes. Recommendations are divided into four sections: (1) screening, diagnosis, glycemic targets, and glycemic monitoring; (2) comorbidities and complications, including obesity and management with lifestyle, nutrition, and bariatric surgery, hypertension, dyslipidemia, retinopathy, neuropathy, diabetic kidney disease, and cardiovascular disease; (3) management of prediabetes, type 2 diabetes with antihyperglycemic pharmacotherapy and glycemic targets, type 1 diabetes with insulin therapy, hypoglycemia, hospitalized persons, and women with diabetes in pregnancy; (4) education and new topics regarding diabetes and infertility, nutritional supplements, secondary diabetes, social determinants of health, and virtual care, as well as updated recommendations on cancer risk, nonpharmacologic components of pediatric care plans, depression, education and team approach, occupational risk, role of sleep medicine, and vaccinations in persons with diabetes.

CONCLUSIONS

This updated clinical practice guideline provides evidence-based recommendations to assist with person-centered, team-based clinical decision-making to improve the care of persons with diabetes mellitus.

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.

Recent updates in the treatment of diabetic polyneuropathy

Distal symmetric diabetic peripheral polyneuropathy (DPN) is the most common form of neuropathy in the world, affecting 30 to 50% of diabetic individuals and resulting in significant morbidity and socioeconomic costs. This review summarizes updates in the diagnosis and management of DPN. Recently updated clinical criteria facilitate bedside diagnosis, and a number of new technologies are being explored for diagnostic confirmation in specific settings and for use as surrogate measures in clinical trials. Evolving literature indicates that distinct but overlapping mechanisms underlie neuropathy in type 1 versus type 2 diabetes, and there is a growing focus on the role of metabolic factors in the development and progression of DPN. Exercise-based lifestyle interventions have shown therapeutic promise. A variety of potential disease-modifying and symptomatic therapies are in development. Innovations in clinical trial design include the incorporation of detailed pain phenotyping and biomarkers for central sensitization.

Diabetes duration and glycaemic control as predictors of cardiovascular disease and mortality

AIMS

To assess the associations of diabetes duration and glycaemic control (defined by plasma glycated haemoglobin [HbA1c] level) with the risks of cardiovascular disease (CVD) and all-cause mortality and to determine whether the addition of either or both to the established CVD risk factors can improve predictions.

MATERIALS AND METHODS

A total of 435 679 participants from the UK Biobank without CVD at baseline were included. Cox models adjusting for classic risk factors (sociodemographic and anthropometric characteristics, lipid profiles and medication use) were used, and predictive utility was determined by the C-index and net reclassification improvement (NRI).

RESULTS

Compared with participants without diabetes, participants with longer diabetes durations and poorer glycaemic control had a higher risk of fatal/nonfatal CVD. Among participants with diabetes, the fully-adjusted hazard ratios (HRs) for diabetes durations of 5 to <10 years, 10 to <15 years and ≥15 years were 1.15 (95% confidence interval [CI] 0.99, 1.34), 1.50 (95% CI 1.26, 1.79) and 2.22 (95% CI 1.90, 2.58; P-trend <0.01), respectively, compared with participants with diabetes durations <5 years. In addition, those with the longest disease duration (≥15 years) and poorer glycaemic control (HbA1c ≥64 mmol/mol [8%]) had the highest risk of fatal/nonfatal CVD (HR 3.12, 95% CI 2.52, 3.86). Among participants with diabetes, the addition of both diabetes duration and glycaemic control levels significantly improved both the C-index (change in C-index +0.0254; 95% CI 0.0111, 0.0398) and the overall NRI for fatal/nonfatal CVD (0.0992; 95% CI 0.0085, 0.1755) beyond the use of the classic risk factors.

CONCLUSIONS

Both longer diabetes duration and poorer glycaemic control were associated with elevated risks of CVD and mortality. Clinicians should consider not only glycaemic control but also diabetes duration in CVD risk assessments for participants with diabetes.

Mean and visit-to-visit variability of glycemia and left ventricular diastolic dysfunction: A longitudinal analysis of 3025 adults with serial echocardiography

OBJECTIVE

We aimed to determine the mean glucose thresholds to increase the risk of left ventricular diastolic dysfunction (LVDD) and whether visit-to-visit variability of fasting plasma glucose (FPG) and glycated hemoglobin (A1C) could independently increase the risk in a cohort with serial echocardiography.

METHODS

This was a 3.5-year (range, 0.5-8.3) retrospective longitudinal cohort study of 3025 adults (age, 55.15 ± 7.6 years; without diabetes, n = 2755) with LV ejection fraction > 50% by serial echocardiography between 2006 and 2016. Mean, standard of deviation (SD) and coefficient of variation (CV) of FPG and A1C obtained from three consecutive measurements preceding the first echocardiography. The definition of LVDD in this study was primarily based on early peak mitral inflow velocity and early diastolic mitral annulus motion velocity.

RESULTS

LVDD developed in 611/3025 subjects (20.2%). Cox proportional hazard models showed increased adjusted hazard ratios (HRs) for incident LVDD in the highest quartile of FPG-mean (HR 1.76, 95% confidence interval [CI]; 1.36-2.30), FPG-SD (HR 1.63, 95% CI; 1.27-2.09), FPG-CV (HR 1.47, 95% CI; 1.15-1.89), and A1C-mean (HR 1.83, 95% CI; 1.41-2.38) versus the lowest quartile, which was consistent even in subjects without diabetes. Mean glucose thresholds for the increased risk were below the lower limits for pre-diabetes.

CONCLUSIONS

In terms of mean glycemia, LVDD may be initiated in the earliest diabetic continuum, and such changes could be measurable within several years. Visit-to-visit variability of FPG, but not that of A1C, predicted accelerated development of LVDD.

Correlations Between Glycemic Parameters Obtained from Continuous Glucose Monitoring and Hemoglobin A1c and Glycoalbumin Levels in Type 2 Diabetes Mellitus

It is difficult to detect glycemic excursions using CGM in daily clinical practice. We retrospectively analyzed CGM data in type T2DM to define the correlations between HbA1c and GA levels at admission and the parameters representing glycemic excursions measured by CGM, including the mean amplitude of glycemic excursions (MAGE) and standard deviation (SD). The MAGE correlated significantly with GA and HbA1c, but not with the GA/HbA1c ratio. The SD correlated significantly with GA, HbA1c, and GA/HbA1c. Multivariate analysis identified the GA value to be the most reflective of MAGE. Patients were divided into 2 groups using a MAGE cutoff value of 75 mg/dl, which reflects stable diabetes. There was a significant difference in GA, but not HbA1c, between the groups with low and high mean amplitudes of glycemic excursions. Receiver operating characteristic curve analysis indicated that the cutoff for GA for identifying patients with MAGE of ≤75 mg/dl was 18.1%. Our study identified GA to be the most reflective of glycemic excursions in patients with T2DM. GA can be a useful index of glycemic excursions and treatment optimization to prevent arteriosclerosis.

Electrodiagnostic assessment of the autonomic nervous system: A consensus statement endorsed by the American Autonomic Society, American Academy of Neurology, and the International Federation of Clinical Neurophysiology

Evaluation of disorders of the autonomic nervous system is both an art and a science, calling upon the physician's most astute clinical skills as well as knowledge of autonomic neurology and physiology. Over the last three decades, the development of noninvasive clinical tests that assess the function of autonomic nerves, the validation and standardization of these tests, and the growth of a large body of literature characterizing test results in patients with autonomic disorders have equipped clinical practice further with a valuable set of objective tools to assist diagnosis and prognosis. This review, based on current evidence, outlines an international expert consensus set of recommendations to guide clinical electrodiagnostic autonomic testing. Grading and localization of autonomic deficits incorporates scores from sympathetic cardiovascular adrenergic, parasympathetic cardiovagal, and sudomotor testing, as no single test alone is sufficient to diagnose the degree or distribution of autonomic failure. The composite autonomic severity score (CASS) is a useful score of autonomic failure that is normalized for age and gender. Valid indications for autonomic testing include generalized autonomic failure, regional or selective system syndromes of autonomic impairment, peripheral autonomic neuropathy and ganglionopathy, small fiber neuropathy, orthostatic hypotension, orthostatic intolerance, syncope, neurodegenerative disorders, autonomic hyperactivity, and anhidrosis.

Inter-practitioner comparisons of nerve conduction studies with standardized techniques in normal subjects: Reap as you sow

This 2-group study was carried out to determine the inter-practitioner difference of nerve conduction studies with standardized techniques.56 normal subjects of 19 to 49 year-old were recruited, 29, and 27 in the 2 labs respectively. Tests were carried out unilaterally on: 5 motor nerve distal latency, conduction velocities (MNCV) and minimum latency of F wave, 3 sensory nerves with negative amplitude, onset, and peak distal latency, sensory nerve distal latency.T-test disclosed 4(15.4%) attributes with statistical significance (P < .05). They were 2 of 4 (50%) compound motor action potentials, which were ulnar and tibial nerve, and 2 of 6 (33.3%) MNCVs, which were elbow-to-wrist MNCV of median nerve and cross-fibula MNCV of peroneal nerve. No differences were disclosed in motor nerve distal latencys, minimum latency of F waves and all sensory attributes.Inconsistency pattern of certain attributes were found. This could be explained with the insufficient definition of related techniques.

Spectrum of diabetic neuropathies

The diabetic state results in neuropathy. The main causative mechanism is hyperglycemia, although microvascular involvement, hypertriglyceridemia, as well as genetic and immune mechanisms may be contributory. There is a growing spectrum of types of diabetic neuropathies that differ based on the type of fibers involved (e.g. myelinated, unmyelinated, autonomic, somatic), distribution of nerves involved, and mechanisms of neuropathy. The most common type is distal sensory neuropathy (DSN), which affects the distal ends of large myelinated fibers, more often sensory than motor, and is often asymptomatic. The next-most common is distal small fiber neuropathy (DSFN), which largely affects the unmyelinated fibers and carries the phenotype of burning feet syndrome. Diabetic autonomic neuropathy (DAN) occurs when widespread involvement of autonomic unmyelinated fibers occurs, and patients can be incapacitated with orthostatic hypotension as well as neurogenic bladder and bowel involvement. Radiculoplexus diabetic neuropathy causes proximal weakness and pain, usually in the lower extremity, and has a combination of immune, inflammatory, and vascular mechanisms. The nerve roots and plexus are involved. These patients present with proximal weakness of a subacute onset, often with severe pain and some autonomic failure. Finally, rapid and sustained reduction of blood glucose can result in treatment-induced diabetic neuropathy (TIND), which largely affects the sensory and autonomic fibers. This occurs if HbA1c is rapidly reduced within 3 months, and the likelihood is proportional to the original A1c and the size of the reduction.

A formula based on autonomic test using EZSCAN and anthropometric data for diagnosis of DM in China

Clinical diagnosis of diabetes mellitus (DM) is time-consuming and invasive. This study aimed to investigate the efficacy and accuracy of EZSCAN in detecting impaired glucose tolerance (IGT) and diabetes mellitus (DM) in Chinese population, and explore a diagnosis formula based on an autonomic test using EZSCAN measurement and anthropometric data. Eligible subjects (n = 1547) had the following data collected: those of anthropometric and EZSCAN measurements and biochemical tests including FPG, OGTT, HbA1c, and serum lipid tests. The support vector machine (SVM) algorithm method was used to derive a diagnostic formula. In this study, 452 and 263 subjects were diagnosed with T2DM and IGT, respectively, while 832 had normal glucose tolerance (NGT). The sensitivity rates for the formula were 77.2% for T2DM and 80.4% for IGT. The diagnostic formula was found to correlate strongly with EZSCAN values. The diagnostic formula based on autonomic test and anthropometric data appears to be a convenient and accurate routine screening option in the Chinese population.

Association Between Diabetic Microangiopathies and Glycemic Variability Assessed by Continuous Glucose Monitoring

The aim of this retrospective study was to elucidate the association between glucose profile using the continuous glucose monitoring system (CGMS) and microvascular complications in patients with type 2 diabetes mellitus (T2DM). The subjects were 160 inpatients with T2DM. The mean blood glucose (MBG) level, percentage of time in a 24-hour period spent with blood glucose level higher than 180 mg/dl (time at >180 mg/dl), standard deviation (SD), and mean amplitude of glycemic excursions (MAGE) were measured continuously over 48 hours using the CGMS. The primary outcome was the association between microvascular complications and glycemic variability. The secondary outcome was the association between microangiopathies and MBG. The SD and MAGE were not associated with presence of microangiopathies or number of complications. There were also no associations between abnormal vibratory sensation in the bilateral lower extremities, coefficient of variation of the R-R interval (CVRR), retinopathy stage, nephropathy stage, or microalbuminuria. MBG was associated, however, with retinopathy, retinopathy stage, and number of complications. Time at >180 mg/dl correlated with abnormal vibratory sensation in the bilateral lower extremities and presence or stage of retinopathy. MBG and time at >180 mg/dl were not associated with presence or stage of nephropathy. Our findings suggest that broad glycemic variability was not associated with microvascular complications, the number of which increased in patients with a high mean glucose level and long time spent with hyperglycemia. It is important, therefore, to reduce the mean glucose level and time spent with hyperglycemia to prevent future microangiopathies.

Nerve ultrasound can distinguish chronic inflammatory demyelinating polyneuropathy from demyelinating diabetic sensorimotor polyneuropathy

Diabetic patients with poor glycaemic control can demonstrate demyelinating distal sensorimotor polyneuropathy (D-DSP) on electrophysiology. Distinguishing D-DSP from chronic inflammatory demyelinating polyneuropathy (CIDP) can be challenging. In this study, we investigated the role of nerve ultrasound in differentiating the two neuropathies. Nerve ultrasound findings of D-DSP patients (fulfilling the electrophysiological but not clinical criteria for CIDP) were compared with non-diabetic CIDP patients (fulfilling both criteria). We studied 108 and 95 nerves from 9 D-DSP and 10 CIDP patients respectively. CIDP patients had significantly larger cross-sectional areas of the median nerve at the mid-arm (17.0 ± 12.5 vs 8.7 ± 2.6; p = 0.005), ulnar nerve at the wrist (7.3 ± 3.1 vs 4.1 ± 1.0; p = 0.001), mid forearm (8.8 ± 5.3 vs 5.5 ± 1.5; p = 0.002) and mid-arm (14.5 ± 14.1 vs 7.5 ± 1.9; p = 0.013), and radial nerve at mid forearm (4.1 ± 2.4 vs 1.2 ± 0.4; p < 0.001). In comparison to D-DSP, CIDP patients had markedly larger nerves at the proximal and non-entrapment sites of the upper limbs, suggesting that nerve ultrasound is useful in differentiating the two neuropathies.

Prevention of cardiovascular disease through reduction of glycaemic exposure in type 2 diabetes: A perspective on glucose-lowering interventions

Type 2 diabetes is a leading cause of cardiovascular disease (CVD). Observational studies have consistently shown an association between glycaemic level and risk of major adverse cardiovascular events (MACE); however, intervention studies have provided limited evidence supporting a reduction in the cardiovascular burden of diabetes through intensive glucose control. In the present review, we aimed to examine the concept of cumulative glycaemic exposure with regard to protection against CVD in diabetes. We address how we can move from a binary approach in trials, to a more quantitative approach based on differences in cumulative glycaemic exposure. We plotted the association between differing glycaemic exposures between study arms and the hazard ratio for MACE in randomized controls trials comparing intensive with conventional glycaemic control in type 2 diabetes. We found a strikingly strong correlation between differential exposure and cardiovascular risk reduction. Similar results were obtained for trials comparing antidiabetes drugs with placebo. The results suggest that a minimum study duration and a minimum gain in glycated haemoglobin (HbA1c) reduction are necessary to drive a relevant risk reduction in CVD risk, and we provide a quantitative perspective in that respect. The present analysis underlines that the duration of the intensification of glycemic control, and the amplitude of the resulting reduction in HbA1c, are important notions for clinical decision-making.

Vascular Complications of Diabetes

Over the last several decades, the global incidence and prevalence of diabetes mellitus has increased significantly. The raised incidence rate is projected to continue as greater numbers of persons adopt a Western lifestyle and diet. Patients with diabetes mellitus are at heightened risk of both adverse microvascular and cardiovascular events. Moreover, once cardiovascular disease develops, diabetes mellitus exacerbates progression and worsens outcomes. The medical management of patients with diabetes mellitus mandates comprehensive risk factor modification and antiplatelet therapy. Recent clinical trials of new medical therapies continue to inform the care of patients with diabetes mellitus to reduce both cardiovascular morbidity and mortality.

Small and large fiber neuropathy in those with type 1 and type 2 diabetes: a 5-year follow-up study

The purpose of this study was to evaluate progression of diabetic polyneuropathy and differences in the spectrum and evolution of large- and small-fiber involvement in patients with diabetes type 1 and 2 over 5 years. Fifty-nine patients (35 type 1 and 24 type 2) were included. Nerve conduction studies (NCS), quantitative sensory testing, skin biopsy for quantification of intraepidermal nerve fiber density (IENFD), symptom scoring and clinical evaluations were performed. Z-scores were calculated to adjust for the physiologic effects of age and height/gender. Neuropathic symptoms were not significantly more frequent in type 2 than in type 1 diabetic patients at follow-up (54% vs. 37%). The overall mean NCS Z-score remained within the normal range, but there was a small significant decline after 5 years in both groups: type 1 (p = 0.004) and type 2 (p = 0.02). Mean IENFD Z-scores changed from normal to abnormal in both groups, but only significantly in those with type 2 diabetes (reduction from 7.9 ± 4.8 to 4.3 ± 2.8 fibers/mm, p = 0.006). Cold perception threshold became more abnormal only in those with type 2 diabetes (p = 0.049). There was a minimal progression of large fiber neuropathy in both groups. Reduction of small fibers predominated and progressed more rapidly in those with type 2 diabetes.

MicroRNA transport in cardiovascular complication of diabetes

MicroRNAs (miRNAs) are post-transcriptional inhibitory regulators of gene expression by binding to complementary messenger RNA (mRNA) transcripts. Extracellular miRNAs are transported by membrane-derived vesicles (exosomes and microparticles), lipoproteins, and other ribonucleoprotein complexes. Extracellular microRNAs are emerging as important mediators of intercellular communications, being involved in the transmission of biological signals between cells. Several miRNAs have been identified as having a primary impact on many biological processes that are of direct relevance to cardiovascular complications of diabetes. Whether the extracellular miRNAs are directly involved in the regulation of these processes is yet to be established. Here, we review recent progresses in extracellular miRNA biology and the role of extracellular miRNA in diabetes induced cardiovascular disease, describing the regulators affecting miRNA transport and the mechanisms for different miRNA transporters. In addition, we discuss the advancement of the research in this field and identify the associated challenges. This article is part of a Special Issue entitled: MicroRNAs and lipid/energy metabolism and related diseases edited by Carlos Fernández-Hernando and Yajaira Suárez.

Serum levels of TGF-β1 in patients of diabetic peripheral neuropathy and its correlation with nerve conduction velocity in type 2 diabetes mellitus

AIMS

To correlate serum levels of TGF-β1 with motor and sensory nerve conduction velocities in patients of type 2 diabetes mellitus

MATERIALS AND METHODS

The study was conducted in diagnosed type 2 diabetes mellitus patients which were divided in patients with clinically detectable peripheral neuropathy of shorter duration (n=37) and longer duration (n=27). They were compared with patients without clinical neuropathy (n=22). Clinical diagnosis was based on neuropathy symptom score (NSS) and Neuropathy disability score (NDS) for signs. Blood samples were collected for baseline investigations and estimation of serum TGF-β1. Nerve conduction velocity was measured in both upper and lower limbs. Median, Ulnar, Common Peroneal and Posterior Tibial nerves were selected for motor nerve conduction study and Median and Sural nerves were selected for sensory nerve conduction study

RESULTS

In patients of type 2 diabetes mellitus with clinically detectable and serum TGF-β1 showed positive correlation with nerve conduction velocities

CONCLUSION

High level of TGF-β1 in serum of T2DM patients with neuropathy show possible contribution in development of neuropathy. Due to its independent association this cytokine might be used as biomarker for diabetic peripheral neuropathy.

Delayed Gastric Emptying Is Associated With Early and Long-term Hyperglycemia in Type 1 Diabetes Mellitus

BACKGROUND & AIMS

After the Diabetes Control and Complications Trial (DCCT), the Epidemiology of Diabetes Interventions and Complications (EDIC) study continued to show persistent benefit of prior intensive therapy on neuropathy, retinopathy, and nephropathy in type 1 diabetes mellitus (DM). The relationship between control of glycemia and gastric emptying (GE) is unclear.

METHODS

We assessed GE with a (13)C-spirulina breath test and symptoms in 78 participants with type 1 diabetes at year 20 of EDIC. The relationship between delayed GE and glycated hemoglobin (HbA1c), complications of DM, and gastrointestinal symptoms were evaluated.

RESULTS

GE was normal (37 participants; 50%), delayed (35 participants; 47%), or rapid (2 participants; 3%). The latest mean HbA1c was 7.7%. In univariate analyses, delayed GE was associated with greater DCCT baseline HbA1c and duration of DM before DCCT (P ≤ .04), greater mean HbA1c over an average of 27 years of follow-up evaluation (during DCCT-EDIC, P = .01), lower R-R variability during deep breathing (P = .03) and severe nephropathy (P = .05), and a greater composite upper gastrointestinal symptom score (P < .05). In multivariate models, retinopathy was the only complication of DM associated with delayed GE. Separately, DCCT baseline HbA1c (odds ratio [OR], 1.6; 95% confidence interval [CI], 1.1-2.3) and duration of DM (OR, 1.2; 95% CI, 1.01-1.3) before DCCT entry and mean HbA1c during DCCT-EDIC (OR, 2.2; 95% CI, 1.04-4.5) were associated independently with delayed GE.

CONCLUSIONS

In the DCCT/EDIC study, delayed GE was remarkably common and associated with gastrointestinal symptoms and with measures of early and long-term hyperglycemia. ClinicalTrials.gov numbers NCT00360815 and NCT00360893.

Near-normoglycaemia and development of neuropathy: a 24-year prospective study from diagnosis of type 1 diabetes

OBJECTIVE

Complete prevention of diabetic neuropathies has not been previously demonstrated. We sought to determine whether long-term near-normoglycaemia maintained from the diagnosis of type 1 diabetes is associated with polyneuropathy and cardiac autonomic dysfunction.

DESIGN

Prospective observational study over 24 years.

SETTING

Ambulatory care.

PARTICIPANTS

32 newly diagnosed patients with type 1 diabetes aged 20.3 ± 1.0 years, duration of diabetes 2.7 ± 0.3 weeks.

INTERVENTION

Insulin therapy according to standards of care.

PRIMARY AND SECONDARY OUTCOME MEASURES

Motor and sensory nerve conduction velocity (MNCV and SNCV), heart rate variability (HRV), and confirmed clinical polyneuropathy measured at 15 time points over 24 years and quantitative sensory testing (QST) determined over 20-22 years.

RESULTS

11 patients were well controlled over 24 years with mean glycated haemoglobin (HbA1c) <7.0% (6.5 ± 0.1%; group 1), whereas 21 patients were poorly controlled (mean HbA1c ≥ 7.0%: 8.3 ± 0.2%; group 2). After 24 years, MNCV was faster in group 1 versus group 2 in the median (55.5 ± 1.6 vs 48.9 ± 1.6 m/s), ulnar (56.5 ± 1.5 vs 49.3 ± 1.7 m/s) and peroneal nerve (44.7 ± 1.6 vs 36.8 ± 2.5 m/s), while SNCV was faster in the median (53.6 ± 1.6 vs 45.5 ± 2.8 m/s), ulnar (54.7 ± 1.8 vs 43.0 ± 3.9 m/s), and sural nerve (44.5 ± 1.8 vs 35.5 ± 2.6 m/s; all p<0.05). The annual decline in peroneal MNCV and sural SNCV in group 1 was sixfold and threefold faster in group 2 than in group 1, respectively. Likewise, impairment in QST and HRV developed at faster rates in group 2. After 24 years, 64% of patients in group 2, but none in group 1, developed confirmed clinical polyneuropathy.

CONCLUSIONS

Near-normoglycaemia maintained from the diagnosis of type 1 diabetes over 24 years was associated with a complete prevention of the decline in hyperglycaemia-related peripheral and autonomic nerve function, and development of confirmed clinical polyneuropathy.

Does prediabetes cause small fiber sensory polyneuropathy? Does it matter?

BACKGROUND AND OBJECTIVES

The association between prediabetes and distal polyneuropathy (DPN) remains controversial. Here we test whether the prevalence of small fiber sensory distal polyneuropathy is increased in prediabetes.

METHODS

Prospectively recruited cohorts of healthy subjects and those with prediabetes from Olmsted County, Minnesota, were assessed for positive neuropathic sensory symptoms, or pain symptoms characteristic of small fiber sensory DPN. Hyperalgesia and hypoalgesia were assessed by "smart" quantitative sensation testing (QST). The prevalence of symptoms and QST abnormalities were compared among the groups.

RESULTS

There was no significant increase in the prevalence of positive neuropathic sensory or pain symptoms, nor of hyper- or hypoalgesia in the prediabetes group. There was an increased prevalence of hypoalgesia of the foot only in newly diagnosed diabetes.

CONCLUSIONS

Based on positive sensory and pain symptoms and QSTs, we did not find an increase in small fiber sensory DPN in prediabetes. Recognizing that obesity and diabetes mellitus are implicated in macro- and microvessel complications, physicians should encourage healthy living and weight loss in patients with prediabetes. In medical practice, alternate causes should be excluded before concluding that small fiber sensory distal neuropathy is secondary to prediabetes.

Prevalence and correlates of diabetic peripheral neuropathy in a Saudi Arabic population: a cross-sectional study

The purpose of this cross-sectional study was to investigate the prevalence and correlates of diabetic peripheral neuropathy (DPN) in a Saudi population. The study population consisted of 552 diabetic participants with an average age of 53.4 years. Among this population, 62.7% were male and 94.9% had type 2 diabetes. The average body mass index was 31.1 kg/m². DPN was diagnosed based on a combination of reduced vibration perception measured by neurothesiometer and/or reduced light touch perception evaluated by the 10-g Semmes-Weinstein monofilament, as well as neurological symptoms. Information on socio-demographic variables, smoking status, duration of diabetes, and medications was obtained through interviews by physicians. Body weight, height, waist circumference, blood pressure and clinical markers were assessed following standard procedures. The prevalence of DPN in this population was 19.9% (95% CI, 16.7%-23.5%). In the multivariable analyses, longer duration of diabetes [odds ratio (OR) for every 5-year increase, 2.49, 95% CI, 1.75-3.53], abdominal obesity (OR, 2.53, 95% CI, 1.41-4.55), and higher levels of fasting blood glucose (OR for every 1 mmol/L increase, 1.05, 95% CI, 0.99-1.12), creatinine (OR for every 10 µmol/L increase, 1.07, 95% CI, 0.99-1.14) and white blood cell count (OR for every 10⁶/L increase, 1.08, 95% CI, 1.01-1.16) were associated with higher odds of DPN, while oral hypoglycemic medication use was associated with a lower odds of DPN (OR, 0.47, 95% CI, 0.26-0.85). In this large Saudi population, several correlates for DPN, in addition to glycemic control and diabetes duration, were identified, including abdominal obesity, creatinine and white blood cell count.

The role of insulin resistance in diabetic neuropathy in Koreans with type 2 diabetes mellitus: a 6-year follow-up study

PURPOSE

We previously reported that insulin resistance, low high-density lipoprotein (HDL) cholesterol, and glycaemic exposure Index are independently associated with peripheral neuropathy in Korean patients with type 2 diabetes mellitus. We followed the patients who participated in that study in 2006 for another 6 years to determine the relationship between insulin resistance and neuropathy.

MATERIALS AND METHODS

This study involved 48 of the original 86 Korean patients with type 2 diabetes mellitus who were referred to the Neurology clinic for the assessment of diabetic neuropathy from January 2006 to December 2006. These 48 patients received management for glycaemic control and prevention of diabetic complications in the outpatient clinic up to 2012. We reviewed blood test results and the nerve conduction study findings of these patients, taken over a 6-year period.

RESULTS

Low HDL cholesterol and high triglycerides significantly influenced the development of diabetic neuropathy. Kitt value (1/insulin resistance) in the previous study affected the occurrence of neuropathy, despite adequate glycaemic control with HbA1c <7%. Insulin resistance affected the development of diabetic neuropathy after 6 years: insulin resistance in 2006 showed a positive correlation with a change in sural sensory nerve action potential in 2012.

CONCLUSION

Diabetic neuropathy can be affected by previous insulin resistance despite regular glycaemic control. Dyslipidaemia should be controlled in patients who show high insulin resistance because HDL cholesterol and triglycerides are strongly correlated with later development of diabetic neuropathy.

Small- and large-fiber neuropathy after 40 years of type 1 diabetes: associations with glycemic control and advanced protein glycation: the Oslo Study

OBJECTIVE

To study large- and small-nerve fiber function in type 1 diabetes of long duration and associations with HbA1c and the advanced glycation end products (AGEs) N-ε-(carboxymethyl)lysine (CML) and methylglyoxal-derived hydroimidazolone.

RESEARCH DESIGN AND METHODS

In a long-term follow-up study, 27 persons with type 1 diabetes of 40 ± 3 years duration underwent large-nerve fiber examinations, with nerve conduction studies at baseline and years 8, 17, and 27. Small-fiber functions were assessed by quantitative sensory thresholds (QST) and intraepidermal nerve fiber density (IENFD) at year 27. HbA1c was measured prospectively through 27 years. Serum CML was measured at year 17 by immunoassay. Serum hydroimidazolone was measured at year 27 with liquid chromatography-mass spectrometry.

RESULTS

Sixteen patients (59%) had large-fiber neuropathy. Twenty-two (81%) had small-fiber dysfunction by QST. Heat pain thresholds in the foot were associated with hydroimidazolone and HbA1c. IENFD was abnormal in 19 (70%) and significantly lower in diabetic patients than in age-matched control subjects (4.3 ± 2.3 vs. 11.2 ± 3.5 mm, P < 0.001). IENFD correlated negatively with HbA1c over 27 years (r = -0.4, P = 0.04) and CML (r = -0.5, P = 0.01). After adjustment for age, height, and BMI in a multiple linear regression model, CML was still independently associated with IENFD.

CONCLUSIONS

Small-fiber sensory neuropathy is a major manifestation in type 1 diabetes of 40 years duration and more prevalent than large-fiber neuropathy. HbA1c and the AGEs CML and hydroimidazolone are important risk factors in the development of large- and small-fiber dysfunction in long-term type 1 diabetes.

Serum levels of TNF-α in peripheral neuropathy patients and its correlation with nerve conduction velocity in type 2 diabetes mellitus

OBJECTIVE

To compare serum levels of TNF-α in patients of peripheral neuropathy and patients without neuropathy in type 2 diabetes mellitus.

MATERIAL AND METHODS

This cross sectional study was conducted in diagnosed type 2 diabetes mellitus patients. They were divided in groups, Group I (n=37) with clinically detectable diabetic peripheral neuropathy of shorter duration and Group II (n=27) with clinically detectable diabetic peripheral neuropathy of longer duration. They were compared with patients without clinical neuropathy (n=22), clinical diagnosis was based on neuropathy symptom score (NSS) and neuropathy disability score (NDS) for signs. Blood samples were collected for baseline investigations and estimation of serum TNF-α. Nerve conduction velocity was measured in both upper and lower limbs. Median, Ulnar, Common Peroneal and Posterior Tibial nerves were selected for motor nerve conduction study and Median and Sural nerves were selected for sensory nerve conduction study.

RESULTS

The comparisons were done between various clinical and biochemical parameters in clinically detectable and undetectable peripheral neuropathy groups of type 2 diabetes mellitus. The study showed raised serum levels of TNF-α in peripheral neuropathy patients and significant correlation with nerve conduction velocity.

CONCLUSION

High level of TNF-α in serum of T2DM patients with neuropathy shows possible contribution in development of neuropathy. Due to its independent association this cytokine might be used as biomarker for diabetic peripheral neuropathy.

A trial of proficiency of nerve conduction: greater standardization still needed

INTRODUCTION

The aim of this study was to test the proficiency (accuracy among evaluators) of measured attributes of nerve conduction (NC).

METHODS

Expert clinical neurophysiologists, without instruction or consensus development, from 4 different medical centers, independently assessed 8 attributes of NC in 24 patients with diabetes mellitus (DM) on consecutive days.

RESULTS

No significant intraobserver differences between days 1 and 2 were found, but significant interobserver differences were seen. Use of standard reference values did not correct for these observed differences.

CONCLUSIONS

Interobserver variability was attributed to differences in performance of NC. It was of sufficient magnitude that it is of concern for the conduct of therapeutic trials. To deal with interrater variability in therapeutic trials, the same electromyographers should perform all NC assessments of individual patients or, preferably, NC procedures should be more standardized. A further trial is needed to test whether such standardization would eliminate interobserver variability.

Autonomic test by EZSCAN in the screening for prediabetes and diabetes

BACKGROUND

Autonomic neuropathy is common in diabetics and may occur in prediabetes. A new and noninvasive autonomic test-EZSCAN evaluates sudomotor function precisely. No generally accepted EZSCAN thresholds to screen for prediabetes and diabetes have been defined.

METHODOLOGY AND PRINCIPAL FINDINGS

Cross-sectional study of 5, 824 Chinese adults aged 40 and older was conducted in Shanghai, China. We used EZSCAN to evaluate autonomic function in different glucose status and screen for prediabetes and diabetes. The prevalence of prediabetes and diabetes were 21.9% and 17.5% respectively. Compared with the lowest quintile, the highest quintile of EZSCAN value had odds ratios for having dysglycemia (prediabetes or diabetes) of 2.08 (95% CI 1.67-2.58) in total population, 2.89 (95% CI 2.06-4.05) in men and 1.70 (95% CI 1.28-2.25) in women after adjustment for confounding factors. EZSCAN value improved the areas under ROC curve for detection of dysglycemia or diabetes beyond the contribution of conventional risk factors by 0.8% and 12.9%. The cut-off point of EZSCAN value higher than 30% provided reasonable sensitivities (70.3-83.7%) to detect dysglycemia not only in total population regardless of sex but also in individuals with high risk of developing diabetes.

CONCLUSIONS AND SIGNIFICANCE

EZSCAN value higher than 30% indicate an increased risk of prevalent prediabetes and diabetes, suggesting that subjects with EZSCAN ≥30% should be further evaluated by oral glucose tolerance test. The improvement of EZSCAN for diabetes detection was still of limited clinical relevance. Thus the clinical application value of EZSCAN is needed to be explored in future studies.

Can ultrasound of the tibial nerve detect diabetic peripheral neuropathy? A cross-sectional study

OBJECTIVE

Peripheral nerve imaging by portable ultrasound (US) may serve as a noninvasive and lower-cost alternative to nerve conduction studies (NCS) for diagnosis and staging of diabetic sensorimotor polyneuropathy (DSP). We aimed to examine the association between the size of the posterior tibial nerve (PTN) and the presence and severity of DSP.

RESEARCH DESIGN AND METHODS

We performed a cross-sectional study of 98 consecutive diabetic patients classified by NCS as subjects with DSP or control subjects. Severity was determined using the Toronto Clinical Neuropathy Score. A masked expert sonographer measured the cross-sectional area (CSA) of the PTN at 1, 3, and 5 cm proximal to the medial malleolus.

RESULTS

Fifty-five patients had DSP. The mean CSA of the PTN in DSP compared with control subjects at distances of 1 (23.03 vs. 17.72 mm(2); P = 0.004), 3 (22.59 vs. 17.69 mm(2); P < 0.0001), and 5 cm (22.05 vs. 17.25 mm(2); P = 0.0005) proximal to the medial malleolus was significantly larger. Although the area under the curve (AUC) for CSA measurements at all three anatomical levels was similar, the CSA measured at 3 cm above the medial malleolus had an optimal threshold value for identification of DSP (19.01 mm(2)) with a sensitivity of 0.69 and a specificity of 0.77 by AUC analysis.

CONCLUSIONS

This large study of diabetic patients confirms that the CSA of the PTN is larger in patients with DSP than in control subjects, and US is a promising point-of-care screening tool for DSP.

Diabetic peripheral neuropathy and the management of diabetic peripheral neuropathic pain

Diabetic peripheral neuropathy (DPN) affects approximately half of patients with diabetes. Neuropathic pain is a major complaint of patients with diabetic polyneuropathy. Diabetic peripheral neuropathy can also lead to autonomic dysfunction. This article provides an outline of the clinical subtypes, pathophysiological features, and diagnosis of DPN. Disease-modifying treatments are reviewed, with particular attention paid to DPN pain management.

Metanx alleviates multiple manifestations of peripheral neuropathy and increases intraepidermal nerve fiber density in Zucker diabetic fatty rats

Metanx is a product containing L-methylfolate, pyridoxal 5'-phosphate, and methylcobalamin for management of endothelial dysfunction. Metanx ingredients counteract endothelial nitric oxide synthase uncoupling and oxidative stress in vascular endothelium and peripheral nerve. This study evaluates Metanx on diabetic peripheral neuropathy in ZDF rats, a model of type 2 diabetes. Metanx was administered to 15-week-old ZDF and ZDF lean rats at either 4.87 mg ⋅ kg(-1) ⋅ day(-1) (a body weight-based equivalent of human dose) or 24.35 mg ⋅ kg(-1) ⋅ day(-1) by oral gavage two times a day for 4 weeks. Both doses alleviated hind limb digital sensory, but not sciatic motor, nerve conduction slowing and thermal and mechanical hypoalgesia in the absence of any reduction of hyperglycemia. Low-dose Metanx increased intraepidermal nerve fiber density but did not prevent morphometric changes in distal tibial nerve myelinated fibers. Metanx treatment counteracted endothelial nitric oxide synthase uncoupling, inducible nitric oxide synthase upregulation, and methylglyoxal-derived advanced glycation end product, nitrotyrosine, and nitrite/nitrate accumulation in the peripheral nerve. In conclusion, Metanx, at a body weight-based equivalent of human dose, increased intraepidermal nerve fiber density and improved multiple parameters of peripheral nerve function in ZDF rats. Clinical studies are needed to determine if Metanx finds use in management of diabetic peripheral neuropathy.

Use of haemoglobin A1c to detect impaired fasting glucose or Type 2 diabetes in a United Kingdom community based population

AIMS

To evaluate the diagnostic accuracy of haemoglobin A1c (HbA1c) in screening for impaired fasting glucose and Type 2 diabetes (T2DM).

METHODS

We screened 3904 adults aged 45-70 (mean age 58.6 [standard deviation (SD) 6.9] years, mean body mass index (BMI) 29.9 [SD 4.7]kg/m(2)), with fasting plasma glucose (FPG) and HbA1c as part of a large diabetes prevention programme. We assessed the diagnostic accuracy of HbA1c for predicting impaired fasting glucose (IFG), (defined either as FPG 5.6-6.9 mmol/l, or 6.1-6.9 mmol/l), and T2DM (FPG ≥ 7.0 mmol/l).

RESULTS

The prevalences of IFG were 13.8% (FPG 5.6-6.9 mmol/l) and 4.5% (FPG 6.1-6.9 mmol/l) and of T2DM was 2.1%. Using FPG 5.6-6.9 mmol/l as the IFG reference standard, HbA1c of 39-47 mmol/mol (5.7-6.4%) was 63% sensitive and 81% specific, and HbA1c 43-47 mmol/mol (6.1-6.4%) was 21% sensitive and 98% specific, in diagnosing IFG. HbA1c ≥ 48 mmol/mol (6.5%) was 61% sensitive and 99% specific in diagnosing T2DM. Having HbA1c 39-47 mmol/mol (5.7-6.4%), male sex, and body mass index >29.5 together increased the odds of IFG 6.5-fold (95% confidence interval (CI) 5.5-7.8) compared to the pre-test odds.

CONCLUSION

Defining 'pre-diabetes' at a lower HbA1c threshold of 39 mmol/mol (5.7%) instead of 47 mmol/mol (6.1%) increases its sensitivity in diagnosing IFG, but current American Diabetes Association definitions of 'pre-diabetes' based on HbA1c would fail to detect almost 40% of people currently classified as IFG. This has implications for current and future diabetes prevention programmes, for vascular risk management, and for clinical advice given to people with 'pre-diabetes' based on fasting glucose data.

Role of ATP-sensitive K+ channels in the antinociception induced by non-steroidal anti-inflammatory drugs in streptozotocin-diabetic and non-diabetic rats

There is evidence that systemic sulfonylureas block diclofenac-induced antinociception in normal rat, suggesting that diclofenac activates ATP-sensitive K(+) channels. However, there is no evidence for the systemic interaction between different non-steroidal anti-inflammatory drugs (NSAIDs) and sulfonylureas in streptozotocin (STZ)-diabetic rats. Therefore, this work was undertaken to determine whether two sulfonylureas, glibenclamide and glipizide, have any effect on the systemic antinociception that is induced by diclofenac (30 mg/kg), lumiracoxib (56 mg/kg), meloxicam (30 mg/kg), metamizol (56 mg/kg) and indomethacin (30 mg/kg) using the non-diabetic and STZ-diabetic rat formalin test. Systemic injections of NSAIDs produced dose-dependent antinociception during the second phase of the test in both non-diabetic and STZ-diabetic rats. Systemic pretreatment with glibenclamide (10 mg/kg) and glipizide (10 mg/kg) blocked diclofenac-induced systemic antinociception in the second phase of the test (P<0.05) in both non-diabetic and STZ-diabetic rats. In contrast, pretreatment with glibenclamide or glipizide did not block lumiracoxib-, meloxicam-, metamizol-, and indomethacin-induced systemic antinociception (P>0.05) in both groups. Results showed that systemic NSAIDs are able to produce antinociception in STZ-diabetic rats. Likewise, data suggest that diclofenac, but not other NSAIDs, activated K(+) channels to induce its systemic antinociceptive effect in the non-diabetic and STZ-diabetic rat formalin test.

Insulin resistance is independently associated with peripheral and autonomic neuropathy in Korean type 2 diabetic patients

In addition to chronic hyperglycemia, insulin resistance itself has been proposed to cause a diabetic neuropathy. We evaluated the role of insulin resistance in the pathogenesis of peripheral and autonomic neuropathy in patients with type 2 diabetes. Eighty-six patients with type 2 diabetes were evaluated for the anthropometric and biochemical profiles, and Kitt value was calculated from insulin tolerance test to assess the insulin resistance. Various autonomic function tests, nerve conduction velocity, and quantitative sensory tests were performed to assess autonomic and peripheral neuropathy. In univariate analysis, both autonomic and peripheral neuropathy were significantly associated with glycemic exposure index (GE index), HDL-cholesterol, duration of DM, and Kitt value. In stepwise linear regression analysis, GE index was an independent predictor of autonomic and peripheral neuropathy (β = 0.643, P < 0.001; β = 0.207, P = 0.013, respectively), and Kitt value was also an independent factor for the autonomic and peripheral neuropathy (β = - 0.306, P < 0.001; β = - 0.329, P < 0.001, respectively). Low HDL-cholesterol increased the odds ratio for peripheral neuropathy. Insulin resistance is independently associated with peripheral and autonomic neuropathy in Korean Type 2 diabetic patients along with hyperglycemia and HDL-cholesterol.

Impaired glycemia and diabetic polyneuropathy: the OC IG Survey

OBJECTIVE

To test whether diabetic polyneuropathies (DPNs), retinopathy, or nephropathy is more prevalent in subjects with impaired glycemia (IG) (abnormality of impaired fasting glucose [IFG], impaired glucose tolerance [IGT], or impaired HbA(1c) [IA1C]) than in healthy subjects (non-IG).

RESEARCH DESIGN AND METHODS

Matched IG and non-IG volunteers were randomly identified from population-based diagnostic and laboratory registries, restudied, and reclassified as non-IG (n = 150), IG (n = 174), or new diabetes (n = 218).

RESULTS

Frequency (%) of DPN in non-IG, IG, and new diabetes was 3 (2.0%), 3 (1.7%), and 17 (7.8%) narrowly defined (no other cause for polyneuropathy) and 19 (12.7%), 22 (12.6%), and 38 (17.4%) broadly defined. Mean and frequency distribution of composite scores of nerve conduction and quantitative sensation tests were not significantly different between IG and non-IG but were worse in new diabetes. Frequency of retinopathy and nephropathy was significantly increased only in new diabetes. In secondary analysis, small but significant increases in retinopathy and nephropathy were found in IGT, IFG, and IGT combined groups.

CONCLUSIONS

In population studies of Olmsted County, Minnesota, inhabitants, prevalence of typical DPN, retinopathy, and nephropathy was significantly increased only in subjects with new diabetes-not in subjects with IG as defined by American Diabetes Association (ADA) criteria of abnormality of IFG, IGT, or IA1C. For atypical DPN, such an increase was not observed even in subjects with new diabetes. In medical practice, explanations other than IG should be sought for patients with atypical DPN (chronic idiopathic axonal polyneuropathy) who have IG.

Modeling nerve conduction criteria for diagnosis of diabetic polyneuropathy

INTRODUCTION

In this study we aimed to determine which criteria are valid for nerve conduction (NC) diagnosis of typical diabetic sensorimotor polyneuropathy (DSPN).

METHODS

Eight criteria were assessed from among diabetes databases, the Rochester Diabetic Neuropathy Study (RDNS, N = 456), and in healthy subjects (RDNS-HS, N = 330).

RESULTS

In the RDNS, the most frequent abnormal attributes (≤2.5th/≥97.5th percentile) are: fibular motor nerve conduction velocity (MNCV; 26.3%); sural sensory nerve conduction velocity (SNAP; 25.4%); tibial MNCV (24.8%); ulnar MNCV (21.3%); fibular F latency (16.9%); and ulnar F latency (16.0%). Normal deviate (from percentiles) composite scores of NC included: representative of neurophysiological abnormalities; sensitive and specific for diagnosis and useful for epidemiological surveys; randomized trials; and medical practice. By contrast, abnormality of one or more attributes in any nerve or abnormally of two most sensitive attributes performed poorly.

CONCLUSIONS

Composite sum scores of normal deviates (from percentiles corrected for applicable variables) of sensitive NC attributes and with modifications, RDNS and AAN criteria performed acceptably for diagnosis of DSPN.

A controlled study of medial arterial calcification of legs: implications for diabetic polyneuropathy

BACKGROUND

Diabetes mellitus (DM) is associated with an increased prevalence of peripheral arterial disease and medial arterial calcification (MAC), possibly related to prevalence and severity of diabetic polyneuropathy (DPN).

OBJECTIVE

To assess the prevalence, risk covariates, and implication of MAC in a controlled study of healthy subjects and patients with DM.

DESIGN

Masked evaluation of radiographs.

SETTING

Olmsted County, Minnesota.

PATIENTS

Ambulatory volunteers with DM from the Rochester Diabetic Neuropathy Study cohort (n = 260) and matched healthy subjects from the Rochester Diabetic Neuropathy Study-Healthy Subject cohort (n = 221).

METHODS

Patients and controls underwent standard radiographs of distal legs and feet from January 1, 1995, through December 31, 2002. The radiographs were independently read by masked, experienced radiologists for vessel calcification. Medial arterial calcification prevalence, risk covariates, correlation with peripheral arterial disease, and implication for distal, length-dependent sensorimotor polyneuropathy (DSPN) were studied.

RESULTS

Of 481 study participants, MAC was found in 66 (13.7%): 55 of 260 (21.2%) in patients with DM and 11 of 221 (5.0%) in healthy subjects (P < .001). Interrater agreement of MAC was 94.1% (κ coefficient of 0.7). Medial arterial calcification was significantly associated with DSPN (P < .001). In stepwise logistic regression analysis, the significant risk covariates for MAC were advancing age, male sex, DM, and stage of microvessel disease (retinopathy).

CONCLUSIONS

Medial arterial calcification of legs was approximately 4 times as prevalent in population-representative ambulatory persons with DM as in healthy subjects. Advancing age, male sex, DM, and retinopathy were the significant risk covariates for MAC of legs. Medial arterial calcification of legs, although significantly associated with DSPN, was not a useful surrogate marker of DSPN. Also, MAC was not shown to be a risk covariate for late worsening of DSPN, although other lines of evidence suggest that peripheral arterial disease may worsen DSPN.

Diabetic polyneuropathies: update on research definition, diagnostic criteria and estimation of severity

Prior to a joint meeting of the Neurodiab Association and International Symposium on Diabetic Neuropathy held in Toronto, Ontario, Canada, 13-18 October 2009, Solomon Tesfaye, Sheffield, UK, convened a panel of neuromuscular experts to provide an update on polyneuropathies associated with diabetes (Toronto Consensus Panels on DPNs, 2009). Herein, we provide definitions of typical and atypical diabetic polyneuropathies (DPNs), diagnostic criteria, and approaches to diagnose sensorimotor polyneuropathy as well as to estimate severity. Diabetic sensorimotor polyneuropathy (DSPN), or typical DPN, usually develops on long-standing hyperglycaemia, consequent metabolic derangements and microvessel alterations. It is frequently associated with microvessel retinal and kidney disease-but other causes must be excluded. By contrast, atypical DPNs are intercurrent painful and autonomic small-fibre polyneuropathies. Recognizing that there is a need to detect and estimate severity of DSPN validly and reproducibly, we define subclinical DSPN using nerve conduction criteria and define possible, probable, and confirmed clinical levels of DSPN. For conduct of epidemiologic surveys and randomized controlled trials, it is necessary to pre-specify which attributes of nerve conduction are to be used, the criterion for diagnosis, reference values, correction for applicable variables, and the specific criterion for DSPN. Herein, we provide the performance characteristics of several criteria for the diagnosis of sensorimotor polyneuropathy in healthy subject- and diabetic subject cohorts. Also outlined here are staged and continuous approaches to estimate severity of DSPN.

Low peripheral nerve conduction velocities and amplitudes are strongly related to diabetic microvascular complications in type 1 diabetes: the EURODIAB Prospective Complications Study

OBJECTIVE

Slow nerve conduction velocity and reduction in response amplitude are objective hallmarks of diabetic sensorimotor polyneuropathy. Because subjective or clinical indicators of neuropathy do not always match well with the presence of abnormal nerve physiology tests, we evaluated associations to nerve conduction in patients with type 1 diabetes.

RESEARCH DESIGN AND METHODS

Nerve conduction studies were performed in the distal sural and ulnar sensory nerves and the peroneal motor nerve in 456 individuals with type 1 diabetes who participated in the follow-up visit of the EURODIAB Prospective Complications Study (EPCS). We used multivariate regression models to describe associations to decreased nerve conduction measures.

RESULTS

In addition to an effect of duration of diabetes and A1C, which were both associated with low nerve conduction velocity and response amplitude, we found that the presence of nephropathy, retinopathy, or a clinical diagnosis of neuropathy was associated with low nerve conduction velocity and amplitude. In the case of nonproliferative retinopathy, the odds ratio (OR) for being in lowest tertile was 2.30 (95% CI 1.13-4.67) for nerve conduction velocity. A similar OR was found for each 2% difference in A1C (2.39 [1.68-3.41]).

CONCLUSIONS

We show that the presence of other microvascular diabetes complications, together with diabetes duration and A1C, are associated with low nerve conduction velocity and amplitude response and that cardiovascular disease or risk factors do not seem to be associated with these measures.

Diabetic neuropathies: update on definitions, diagnostic criteria, estimation of severity, and treatments

Preceding the joint meeting of the 19th annual Diabetic Neuropathy Study Group of the European Association for the Study of Diabetes (NEURODIAB) and the 8th International Symposium on Diabetic Neuropathy in Toronto, Canada, 13-18 October 2009, expert panels were convened to provide updates on classification, definitions, diagnostic criteria, and treatments of diabetic peripheral neuropathies (DPNs), autonomic neuropathy, painful DPNs, and structural alterations in DPNs.