Epidemiological correlates of diabetic neuropathy. Report from Pittsburgh Epidemiology of Diabetes Complications Study

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

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

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

OBJECTIVE

The degree to which chronic glycemic exposure (CGE) (fasting plasma glucose [FPG], HbA1c [A1C], duration of diabetes, age at onset of diabetes, or combinations of these) is associated with or predicts the severity of microvessel complications is unsettled. Specifically, we test whether combinations of components correlate and predict complications better than individual components.

RESEARCH DESIGN AND METHODS

Correlations and predictions of CGE and complications were assessed in the Rochester Diabetic Neuropathy Study, a population-based, cross-sectional, and longitudinal epidemiologic survey of 504 patients with diabetes followed for up to 20 years.

RESULTS

In multivariate analysis, A1C and duration of diabetes (and to a lesser degree age at onset of diabetes but not FPG) were the main significant CGE risk covariates for complications. A derived glycemic exposure index (GE(i)) correlated with and predicted complications better than did individual components. Composite or staged measures of polyneuropathy provided higher correlations and better predictions than did dichotomous measures of whether polyneuropathy was present or not. Generally, the mean GE(i) was significantly higher with increasing stages of severity of complications.

CONCLUSIONS

A combination of A1C, duration of diabetes, and age at onset of diabetes (a mathematical index, GE(i)) correlates significantly with complications and predicts later complications better than single components of CGE. Serial measures of A1C improved the correlations and predictions. For polyneuropathy, continuous or staged measurements performed better than dichotomous judgments. Even with intensive assessment of CGE and complications over long times, only about one-third of the variability of the severity of complications is explained, emphasizing the role of other putative risk covariates.

The prevalence of neuropathy and relationship with risk factors in diabetic patients: a single-center experience

OBJECTIVE

To determine the rate of distal symmetrical polyneuropathy (DSP) in patients with type 2 diabetes mellitus, to evaluate the role of history, neurological examination and the electrodiagnostic methods in the diagnosis of DSP, and to determine the association between electromyography-supported neuropathy (ESN), neuropathic complaints (NCs) and risk factors.

SUBJECTS AND METHODS

A total of 191 type 2 DM patients (109 female, 82 male; mean age 58.7 +/- 10 years) were recruited. The NCs were recorded. All patients had electromyographic (EMG) examinations. The relationship between ESN, NCs and risk factors were evaluated.

RESULTS

Of the 191 patients, 83 (43.5%) had DSP on EMG examinations and 92 (48.2%) patients suffered from NCs. Among the ESN patients, a significant relationship existed with HbA1(c) level, illness duration, smoking, male gender or insulin usage (p < 0.05) but not with age, hypertension, hypercholesterolemia or hypertriglyceridemia. The frequency of NCs was higher in patients with ESN. There was also a significant association between NCs and ESN (p < 0.05). The presence of NCs was not related to age, gender, smoking, hypertension, hypercholesterolemia and hypertriglyceridemia (p > 0.05) but NCs were correlated to HbA1(c) level, illness duration and insulin usage (p < 0.05).

CONCLUSION

Our data show that a strong association exists between the presence of DSP and illness duration, HbA1(c), smoking, thereby indicating that cessation of smoking and near normal glycemic control would be additional precautions to delay the beginning or progression of polyneuropathy.

Potential risk factors for diabetic neuropathy: a case control study

Background

Diabetes mellitus type II afflicts at least 2 million people in Iran. Neuropathy is one of the most common complications of diabetes and lowers the patient's quality of life. Since neuropathy often leads to ulceration and amputation, we have tried to elucidate the factors that can affect its progression.

Methods

In this case-control study, 110 diabetic patients were selected from the Shariati Hospital diabetes clinic. Michigan Neuropathic Diabetic Scoring (MNDS) was used to differentiate cases from controls. The diagnosis of neuropathy was confirmed by nerve conduction studies (nerve conduction velocity and electromyography). The multiple factors compared between the two groups included consumption of angiotensin converting enzyme inhibitors (ACEI), blood pressure, serum lipid level, sex, smoking, method of diabetes control and its quality.

Results

Statistically significant relationships were found between neuropathy and age, gender, quality of diabetes control and duration of disease (P values in the order: 0.04, 0.04, < 0.001 and 0.005). No correlation was found with any atherosclerosis risk factor (high BP, hyperlipidemia, cigarette smoking).

Conclusion

In this study, hyperglycemia was the only modifiable risk factor for diabetic neuropathy. Glycemic control reduces the incidence of neuropathy, slows its progression and improves the diabetic patient's quality of life. More attention must be paid to elderly male diabetic patients with poor diabetes control with regard to regular foot examinations and more practical education.

Impact of overweight on chronic microvascular complications in type 1 diabetic patients

OBJECTIVE

To investigate a possible association of BMI with retinopathy and neuropathy in type 1 diabetes. Retinopathy and neuropathy may not only be related to glycemic control and diabetes duration but also to blood pressure and BMI.

RESEARCH DESIGN AND METHODS

A total of 592 type 1 diabetic patients without nephropathy were studied (M/F: 324/268; age: 41 +/- 12 years; duration: 19 +/- 11 years; HbA(1c) [A1C]: 7.9 +/- 1.1%). Patients were subdivided according to BMI: 168 men and 146 women with BMI <25 kg/m(2), and 156 men and 122 women with BMI > or =25 kg/m(2). Retinopathy was examined by fundoscopy and neuropathy by electromyography.

RESULTS

Hypertension (>130/85 mmHg) was present in 40%, retinopathy in 53%, and neuropathy in 43% of patients. Overweight subjects had more retinopathy (63 vs. 45%, P < 0.0001, odds ratio [OR] = 2.1) and neuropathy (49 vs. 38%, P = 0.008, OR = 1.6) than normal-weight patients. Patients with retinopathy were older (45 +/- 12 vs. 37 +/- 11 years, P < 0.0001) and had a longer diabetes duration (25 +/- 10 vs. 12 +/- 8 years, P < 0.0001), a higher A1C (8.0 +/- 1.1 vs. 7.7 +/- 1.1%, P = 0.001), and a higher BMI (25.8 +/- 4.1 vs. 24.7 +/- 4.2 kg/m(2), P = 0.001) than individuals without retinopathy. The same results are found in neuropathy. Logistic regression analysis showed that diabetes duration (beta = 0.15, P < 0.0001), blood pressure (beta = 0.22, P = 0.0047), and A1C (beta = 0.24, P = 0.01), but not BMI, lipid levels, sex, or age, were independent risk factors for retinopathy. Likewise, duration (beta = 0.05, P < 0.0001), age (beta = 0.04, P = 0.0001), A1C (beta = 0.35, P < 0.0001), and sex (beta = 0.74, P = 0.0001) but not BMI, lipid levels, or hypertension were independently associated with neuropathy. Men had more neuropathy than women (50 vs. 34%, P < 0.0001, OR = 1.9). Leptin and adiponectin levels did not differ between individuals with or without microvascular complications.

CONCLUSIONS

Retinopathy and neuropathy are more prevalent in overweight (BMI > or =25 kg/m(2)) type 1 diabetic subjects. However, logistic regression analysis showed that diabetes duration and A1C remain the main determinants for retinopathy and neuropathy.

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

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

Altered nerve excitability properties in established diabetic neuropathy

The underlying cause of diabetic neuropathy remains unclear, although pathological studies have suggested an ischaemic basis related to microangiopathy, possibly mediated through effects on the energy-dependent Na+/K+ pump. To investigate the pathophysiology of diabetic neuropathy, axonal excitability techniques were undertaken in 20 diabetic patients with neuropathy severity graded through a combination of quantitative sensory testing (QST) using a vibratory stimulus, assessment of symptom severity using the Total Neuropathy Symptom Score (T-NSS) and measurement of glycosylated haemoglobin as a marker of disease control. To assess axonal excitability, compound muscle action potentials were recorded at rest from abductor pollicis brevis following stimulation of the median nerve, and stimulus-response behaviour, threshold electrotonus, a current-threshold relationship and the recovery of excitability were recorded in each patient. All patients had established neuropathy, with abnormalities of T-NSS present in all patients and QST abnormalities present in 65%. Compared with controls, diabetic neuropathy patients had significant reduction in maximal CMAP amplitude (P < 0.0005), accompanied by a 'fanning in' of threshold electrotonus. In addition, the strength-duration time constant was decreased in diabetic neuropathy patients and recovery cycles were altered with reductions in refractoriness, the duration of the relative refractory period, superexcitability and subexcitability. It is proposed that while the changes in threshold electrotonus with supportive findings in the current-threshold relationship are consistent with axonal depolarization, possibly mediated by a decrease in Na+/K+ pump activity, the alterations in the recovery cycle of excitability could be explained on the basis of a smaller action potential, reflecting a limitation on the nodal driving current imposed by a reduction in Na+ conductances.

Effect of Glycemic Control on Electrophysiologic Changes of Diabetic Neuropathy in Type 2 Diabetic Patients

Diabetic neuropathy is a common complication of diabetes mellitus. Effective blood glucose control retards changes in nerve conduction velocity in type 1 diabetes. This study examined the relationship between glycemic control and electrophysiologic changes in diabetic neuropathy in 57 type 2 diabetic patients. Nerve conduction in the peroneal motor nerve, tibial motor nerve, and sural nerve were measured at study entry and at follow-up 24+/-3.12 months later. Changes in individual nerves are expressed as a percentage change (PC) and overall electrophysiologic changes are expressed as the sum of individual PCs. The PCs for peroneal motor nerve velocity, tibial motor nerve velocity, and sural nerve velocity were all lower in patients with a mean HbA1c of 8.5% or less compared with those in patients with a mean HbA1c of more than 8.5%, and SPCV (sum of PC in velocity) was significantly inversely correlated with mean HbA1c. However, there was no significant difference in SPCV in subjects with or without hypertension, hypertriglyceridemia, or low high-density lipoprotein cholesterol concentration. In conclusion, hyperglycemia is the most important etiology for electrophysiologic progression in type 2 diabetic patients. Furthermore, a mean HbA1c of more than 8.5% will result in significant deterioration in electrophysiology.

Changing the Natural History of Diabetic Neuropathy: Incidence of Ulcer/Amputation in the Contralateral Limb of Patients With a Unilateral Nerve Decompression Procedure

The natural history of diabetes neuropathy is progressive and irreversible loss of sensibility in the feet, leading to ulceration and/or amputation in 15% of patients. The prevalence of neuropathy is more than 50% in those who have been diabetic for 20 years. Decompression of the tibial and peroneal nerves in those with diabetic neuropathy improves sensation in 70% of patients. The impact of this surgery on the development of ulcers and amputations in both the operated and the contralateral, nonoperated limb was evaluated in a retrospective analysis of 50 patients with diabetes a mean of 4.5 years (range, 2-7 years) from the date of surgery. No ulcers or amputations occurred in the index limb of these patients. In contrast, there were 12 ulcers and 3 amputations in 15 different patients in contralateral limbs. This difference was significant at P < 0.001. It is concluded that decompression of lower extremity nerves in diabetic neuropathy changes the natural history of this disease, representing a paradigm shift in health care costs.

Chronic painful peripheral neuropathy in an urban community: a controlled comparison of people with and without diabetes

AIMS

A cross-sectional study has been performed in order to estimate the prevalence, severity, and current treatment of chronic painful peripheral neuropathy (CPPN) in people with diabetes in the community.

METHODS

Using a structured questionnaire and examination we have assessed these factors in a community sample of people with diabetes (n=350) and compared them with 344 age- and sex-matched people without diabetes from the same locality.

RESULTS

The prevalence of CPPN was estimated to be 16.2%[95% confidence interval (CI): 6.8-16%] in people with diabetes compared with 4.9% (95% CI: 2.6-7.2%) in the control sample (P < 0.0001). Diabetic subjects with and without CPPN did not differ in age, sex, type and duration of diabetes, body mass index, smoking status and glycaemic control. However, CPPN diabetic subjects had significantly higher Visual Analogue Scale (VAS) scores for pain over the preceding 24 h [median (interquartile range) 3.5 (1.5-6.7) cm vs. 0.7 (0-3.9) cm, P < 0.0001]. Also, the total McGill Pain Questionnaire Score (a measure of pain quality and severity) was 18 (13-31.5) vs. 10 (4-16) (P < 0.0001). Of patients with diabetes and CPPN, 12.5% (7/56) had never reported their symptoms to their treating physician and 39.3% (22/56) had never received any treatment for their painful symptoms.

CONCLUSIONS

CPPN is common, often severe but frequently unreported and inadequately treated.

Diabetic neuropathy in children and adolescents

Diabetic neuropathy (DN) represents a major complication of type 1 diabetes mellitus (T1DM) but there is considerable uncertainty as to its incidence, prevalence, diagnosis and prognosis in pediatric population. Generally, DN is classified as polyneuropathy, focal neuropathy and autonomic neuropathy. The latter seems to be detectable even in asymptomatic children and adolescents with diabetes and is associated with the most serious consequences, such as hypoglycemia unawareness and cardiovascular dysfunction. A near-normal control of blood glucose in the early years after onset of diabetes may delay the development of clinically significant nerve impairment and, therefore, children and adolescents with diabetes represent a critical target for primary prevention of this complication. The aim of this review is to focus on the main clinical, epidemiological and prognostic aspects of DN in children and adolescents with T1DM. Etiopathogenetic theories and diagnostic tools are also reviewed from in a pediatric perspective.

Asp299Gly and Thr399Ile genotypes of the TLR4 gene are associated with a reduced prevalence of diabetic neuropathy in patients with type 2 diabetes

OBJECTIVE

To establish whether single nucleotide polymorphisms (Asp299Gly and Thr399Ile) of the toll-like receptor 4 have an association with late diabetic complications.

RESEARCH DESIGN AND METHODS

The study was conducted in 246 type 1 and 530 type 2 diabetic patients. The alleles of both polymorphisms were detected using PCR and subsequent cleavage by NcoI and HinfI restriction endonucleases.

RESULTS

No difference was found between type 1 and type 2 diabetic patients in the prevalence of alleles of the Asp299Gly and Thr399Ile polymorphisms. In most cases, the alleles Gly299 and Ile399 occurred in a co-segregatory manner. The prevalence of the Gly299/Ile399 haplotype was 10.6 and 12.1% in type 1 and type 2 diabetic patients, respectively (P = 0.63). No association with diabetic nephropathy or diabetic neuropathy was found in type 1 diabetic patients. In type 2 diabetic patients, however, heterozygote carriers of the Asp299Gly and Thr399Ile genotypes had a significantly reduced prevalence of diabetic neuropathy (odds ratio 0.35 [95% CI 0.19-0.61]; P = 0.0002); no association with diabetic nephropathy was found.

CONCLUSIONS

Our data indicate that Asp299Gly and Thr399Ile genotypes of the TLR4 gene are associated with reduced prevalence of diabetic neuropathy in type 2, but not in type 1, diabetes. Thus different mechanisms may be involved in the pathophysiology of diabetic neuropathy in type 1 and type 2 diabetes.

Optimal blood glucose control during 18 years preserves peripheral nerve function in patients with 30 years' duration of type 1 diabetes

OBJECTIVE

To assess the association between 18 years of mean HbA(1c) and nerve conduction parameters of the lower limb in patients with type 1 diabetes of 30 years' duration.

RESEARCH DESIGN AND METHODS

HbA(1c) has been examined prospectively since 1982 in a group of 39 patients with type 1 diabetes. Mean age at baseline was 25 years (range 18-40) with 12 years' disease duration. The mean age at diagnosis of diabetes was 12.5 years. Nerve function of lower limbs was assessed at baseline, after 8 years, and after 18 years.

RESULTS

A total of 23 men and 16 women were studied. Mean age was 43 years. Mean HbA(1c) was 8.2% (range 6.6-11.3) during 18-year follow-up. Nerve conduction velocity (NCV) and nerve action potential amplitude (NAPA) at the last examination were significantly associated with mean HbA(1c) (P < 0. 05). From 1982 to 1999, there was a significant reduction in nerve function in patients with mean HbA(1c) >or=8.4% (highest tertile). For example, the mean NCV in the tibial nerve was reduced from 47 to 31 m/s (P < 0.01). The number of nerves with NCV (P < 0.01) and NAPA (P = 0.01) reduced to below the reference level in each patient was also significantly associated to mean HbA(1c). No significant associations were found between nerve function parameters, sex, disease duration, blood pressure, serum cholesterol, microalbuminuria, or smoking.

CONCLUSIONS

The present study shows that mean HbA(1c) is a strong predictor of nerve function. Mean HbA(1c) <8.4% over 18 years was associated with near-normal nerve function.

Pharmacotherapy of painful diabetic neuropathy

The scope of this review is to describe the epidemiology, physiology, symptomatology, and treatment of diabetic painful neuropathy, which is a common complication of diabetes with significant morbidity. This article focuses on treatment options. Various clinical trials of several classes of medications (eg, antidepressants, anticonvulsants, and topical medications) and alternative treatments (eg, acupuncture, electrostimulation, magnets) are reviewed. Physicians have a large panel of medications that can be used effectively solely or in combination at their disposal. However, a number of these treatments have significant side effects, which are noted, that limit their use. As the understanding of the pathophysiologic mechanisms of diabetic neuropathy improves, new medications are under investigation, which are reviewed in this article. There is great hope that the future may hold treatments that would prevent nerve damage.

Lipoprotein subclass measurements by nuclear magnetic resonance spectroscopy improve the prediction of coronary artery disease in Type 1 diabetes. A prospective report from the Pittsburgh Epidemiology of Diabetes Complications Study

AIM/HYPOTHESIS

To examine whether nuclear magnetic resonance lipoprotein spectroscopy improves the prediction of coronary artery disease in patients with Type 1 diabetes, independently of conventional lipid and other risk factors.

METHODS

A prospective nested case-control design of subjects with childhood onset Type 1 diabetes from the Pittsburgh Epidemiology of Diabetes Complications Study was used. 59 controls were age-, sex- and duration-matched to 59 incident cases of coronary artery disease (fatal or non-fatal myocardial infarction, angina, coronary stenosis >50%) occurring during 10 years of follow-up. Lipid mass and particle concentrations of VLDL, LDL, and HDL subclasses, grouped into three size categories (large, medium, and small), were assessed prior to event with nuclear magnetic resonance spectroscopy.

RESULTS

Univariate analyses showed that both lipid mass and particle concentrations of all three VLDL subclasses, small LDL, medium LDL, and medium HDL were increased in CAD cases compared to controls, while large HDL was decreased. Mean LDL and HDL particle sizes were lower in cases. In multivariate models using conventional lipid and non-lipid risk factors, triglycerides and overt nephropathy were the strongest predictors of CAD. Nuclear magnetic resonance measures further improved the prediction, i.e. large HDL particle concentration (OR=0.43, p=0.030), medium HDL mass (OR=3.79, p=0.026) and total VLDL particle concentration (OR=2.33, p=0.033).

CONCLUSION/INTERPRETATION

While these results underscore the importance of triglycerides and overt nephropathy in CAD risk in Type 1 diabetic patients, they also suggest that nuclear magnetic resonance lipoprotein spectroscopy could further refine its prediction and show novel findings concerning HDL subclasses.

Validation of the Toronto Clinical Scoring System for diabetic polyneuropathy

OBJECTIVE

The aim of the current study was to determine the validity of the Toronto Clinical Scoring System (CSS) in reflecting the presence and severity of diabetic peripheral sensorimotor polyneuropathy (DSP) as determined by myelinated fiber density (FD) on sural nerve biopsy.

RESEARCH DESIGN AND METHODS

Eighty-nine patients with both type 1 and type 2 diabetes, ascertained from a large therapeutic randomized controlled trial, were included in this cross-sectional, observational cohort study. Morphological severity of DSP was expressed as the FD in the sural nerve biopsy. The Toronto CSS was applied to all patients to determine a clinical neuropathy score. General linear regression models were used to assess the relationship between the morphological severity of DSP and the Toronto CSS.

RESULTS

The Toronto CSS showed a significant negative correlation with sural nerve FD (R(2) = 0.256, P < 0.0001). The Toronto CSS was lower in those with better glycemic control (HbA(1c) </=8%). Sural nerve FD and the Toronto CSS showed strong correlations with electrophysiology, by both summed amplitude and summed conduction velocity values.

CONCLUSIONS

The Toronto CSS is a valid instrument to reflect the presence and severity of DSP as measured by sural nerve morphology and electrophysiology. The results of the current study underscore the interrelationships between clinical deficits, electrophysiological findings, and morphological changes in DSP. This evidence suggests that the Toronto CSS may prove useful in documenting and monitoring DSP in the clinic and in clinical research trials.

Longitudinal assessment of the development of diabetic polyneuropathy and associated risk factors

AIMS

To longitudinally assess risk factors for diabetic polyneuropathy (DPN) severity, and to longitudinally assess risk factors for the change of DPN severity during 2-4 years of follow-up.

METHODS

From 1995 to 1999, 486 Type 2 diabetes patients in general practice were examined annually with regard to DPN severity and its possible risk factors. DPN severity was assessed with a clinical neurological examination (CNE) which included pinprick sense, light touch sense, vibration sense and ankle jerk. Longitudinal (multivariate) linear associations of (change of) CNE score and predicting variables were analysed using multilevel analyses.

RESULTS

In this population, 50% of participants were men and had a mean age of 65.4 years, almost one-third (31.7%) of the participants had a CNE score > 4 at baseline and were classified with DPN. CNE score significantly increased during follow-up. Among participants not graded with DPN at baseline, 21.3% progressed towards a CNE score > 4 after 3 years of follow-up. Longitudinal multivariate analyses showed that age, diabetes duration, HbA1c, height, body mass index and ankle-arm index together best predicted CNE score during follow-up. Change of CNE score during follow-up was best predicted by age, diabetes duration and HbA1c, with the latter being the strongest predictor.

CONCLUSIONS

Although several factors are longitudinally associated with DPN, HbA1c, age and diabetes duration were the best predictors of CNE change during follow-up. Therefore, improving glycaemia remains an important amenable factor in preventing worsening of diabetic polyneuropathy.

Risk factors for diabetic neuropathy and foot ulceration

Peripheral sensory neuropathy (PSN) and foot ulcers are disabling and expensive complications of diabetes with few therapeutic options. Knowledge of risk factors for both complications, based on prospective observational studies, permits identification of individuals at high risk and provides options for intervention. Glycemia is the main modifiable risk factor for PSN, whereas PSN and trauma are the principal potentially modifiable risk factors for the development of foot ulceration.

Peripheral nerve function is increasingly impaired during puberty in adolescents with type 1 diabetes

OBJECTIVE

To evaluate the impact of puberty on peripheral nerve function in adolescents with type 1 diabetes.

RESEARCH DESIGN AND METHODS

Of 138 eligible patients with type 1 diabetes, 100 patients (age >9 years and diabetes duration >2 years) attending an outpatient diabetes clinic and 100 age- and sex-matched healthy control subjects took part in this cross-sectional study. Peripheral motor and sensory nerve conduction tests, cardiovascular reflex tests on the autonomic nervous system, and measurements of vibration-perception threshold (VPT) were performed.

RESULTS

Nerve conduction velocity (NCV) in the distal motor and sensory nerves, the motor nerve distal latency, and the sensory nerve action potential (SNAP) amplitude were impaired in the adolescent patients with type 1 diabetes. The deterioration in motor NCV, H-reflex latency, and SNAP amplitude became more conspicuous in late puberty and postpuberty and was related to poor metabolic control. A total of 10 patients had distal diabetic polyneuropathy (DP) neurophysiologically, and these patients had significantly lower heart-rate variation in the deep breathing test than the other patients. Three of the patients with DP had peripheral neurological signs or symptoms. A slight difference in the VPT between the patients and control subjects was observed after puberty.

CONCLUSIONS

Increasing subclinical motor nerve impairment can be detected during late puberty and after puberty, and sensory NCV and SNAP amplitude are reduced in adolescents with type 1 diabetes. Poor metabolic control during puberty appears to induce deteriorating peripheral neural function in young patients with type 1 diabetes.

New trends in the etiopathogenesis of diabetic peripheral neuropathy

Neuropathy is well recognized as a major complication of insulin-dependent diabetes mellitus in adults, resulting in significant morbidity and possibly an increased mortality. Both the peripheral and autonomic nervous systems can be involved, and adolescents with diabetes can show early evidence of neuropathy. The pathogenesis of diabetic neuropathy remains unclear but is thought to involve various mechanisms. This complication can be traced to the metabolic effects of hyperglycemia and/or other effects of insulin deficiency on the various constituents of the peripheral nerve. The polyol pathway and/or nonenzymatic glycation affecting one or more cell types in the multicellular constituents of the peripheral nerve appear likely to have an inciting role. The role of other factors, such as possible direct neurotrophic effects of insulin and insulin-related growth factors, seems to be relevant.

Factor analysis of thermal and vibration thresholds in young patients with Type 1 diabetes mellitus

AIMS

To identify factors that represent relationships among sets of interrelated thermal and vibration threshold variables and to find clinical correlates that are significantly associated with these factors.

METHODS

Thermal and vibration perception thresholds were tested in the hands and feet of Type 1 diabetic patients treated in an outpatient clinic for juvenile-onset diabetes. Factor analysis was used to identify factors that represent relationships among sets of thermal and vibration threshold variables.

RESULTS

One hundred and forty-eight patients (47.3% males, median current age 22.3 years and median duration of diabetes 11.4 years) were evaluated. Three factors explained 77% of the total variance: 'hand sensation' factor, underlying cold, warmth and vibration perception thresholds in the hand; 'foot sensation' factor, underlying the same sensory thresholds in the foot; and 'heat-related pain' factor, underlying heat pain perception threshold in both limbs. The 'foot sensation' factor was the only factor that significantly correlated with diabetes-related variables (e.g. duration and cumulative glycaemic control of the disease) and concurrent diabetic microangiopathy. Male sex was associated with higher values of the 'heat-related' factor, while the 'hand sensation' factor did not correlate with any of the study variables.

CONCLUSIONS

The distribution of the various thermal and vibration threshold variables according to the three factors may point at length-dependent mechanism of axonal degeneration. Cold, warmth and vibration perception thresholds in the foot may be the only valuable psychophysical parameters in the evaluation of early sensory impairment associated with diabetes.

Diabetic neuropathy--a continuing enigma

In this article we will review the clinical signs and symptoms of diabetic somatic polyneuropathy (DPN), its prevalence and clinical management. Staging and classification of DPN will be exemplified by various staging paradigms of varied sophistication. The results of therapeutic clinical trials will be summarized. The pathogenesis of diabetic neuropathy reviews an extremely complex issue that is still not fully understood. Various recent advances in the understanding of the disease will be discussed, particularly with respect to the differences between neuropathy in the two major types of diabetes. The neuropathology and natural history of diabetic neuropathy will be discussed pointing out the heterogeneities of the disease. Finally, the various prospective therapeutic avenues will be dealt with and discussed.

Maculopathy in patients with diabetes mellitus type 1 and type 2: associations with risk factors

AIM

To examine possible relation between diabetic maculopathy and various risk factors for diabetic complications in patients with diabetes mellitus type 1 and type 2.

METHODS

Cross sectional study of two cohorts of diabetic patients, comprising 1796 patients with type 1 diabetes (mean age 47 years, mean duration of diabetes 24 years) and 1563 patients with type 2 diabetes (mean age 62 years, mean duration of diabetes 16 years). Retinopathy levels (R0-RV) and maculopathy were assessed by fluorescence angiography and fundus photography and binocular biomicroscopy. Diabetic neuropathy was assessed by means of computer assisted electrocardiography and by thermal and vibratory sensory examination. Patients were classified as normoalbuminuric (<20 microg/min) or microalbuminuric (20-200 microg/min) according to their albumin excretion rates measured in urine collected overnight. Using univariate analyses, the effects of selected patient characteristics on the presence of maculopathy were evaluated. Multiple logistic regression analyses were performed to determine independent effects of risk variables on diabetic maculopathy.

RESULTS

Background retinopathy (RII) was found to be present in 28% of type 1 diabetic patients and in 38% of type 2 diabetic patients. The prevalence of maculopathy in these patients was remarkably high (42% in type 1 and 53% in type 2 diabetic patients). Patients with maculopathy had significantly impaired visual acuity. Multiple logistic correlation analysis revealed that in both types of diabetes maculopathy exhibited independent associations with duration of diabetes and with neuropathy (p <0. 01); in type 1 diabetic patients there were significant associations with age at diabetes onset, serum triglyceride and total cholesterol levels (p <0.05); in type 2 diabetes with serum creatinine levels and with hypertension (p <0.05).

CONCLUSIONS

Irrespective of the type of diabetes, diabetic patients with long standing diabetes have a high risk for the development of diabetic maculopathy. Diabetic maculopathy is closely associated with diabetic nephropathy and neuropathy and with several atherosclerotic risk factors which suggests that these factors might have an important role in the pathogenesis of maculopathy. However, prospective trials are necessary to evaluate the predictive value of such factors. The findings of the present cross sectional study reinforce the arguments of previous studies by others for tight control of hypertension and hyperglycaemia.

Modeling impairment: using the disablement process as a framework to evaluate determinants of hip and knee flexion

Elders often present to health care providers with multiple inter-related conditions that determine an individual's ability to function. The disablement process provides a generalized sociomedical framework for investigating the complex pathways from chronic disease to disability. At each stage of the main pathway, associations may exist among primary physical factors and modifying variables that ultimately have downstream effects on the progression toward disability. The purpose of the present analysis is to examine the inter-relationships between a cohesive set of variables primarily at the level of impairment that may affect hip and knee flexion range of motion (ROM). The San Antonio Longitudinal Study of Aging enrolled 833 community dwelling Mexican (MA) and European American (EA) elders aged 64-78 years between 1992 and 1996. Of these, 647 had complete data from both a home-based and performance-based battery of assessments for these analyses. Concerning impairments, hip ROM was measured using an inclinometer, and knee ROM using a goniometer. Pain location and intensity were assessed using the McGill Pain Questionnaire. Peripheral vascular disease was assessed using doppler brachial and ankle systolic blood pressures. Ankle and knee reflexes, and vibratory sensation were assessed by a standardized neurological examination. As to diseases, diabetes was assessed using a combination of blood glucose levels and self-report, and arthritis by self-report. Concerning modifying variables, height and weight were directly measured and used to calculate BMI. Activity level was assessed with the Minnesota Leisure Time Questionnaire. Analgesic use was assessed by direct observation of medications taken within the past two weeks. We used structural equation modeling to test associations between the variables that were specified a priori. These analyses demonstrate the central role of BMI as a determinant of hip and knee flexion ROM. For an increase in level of BMI, the coefficients [SEM] for changes in levels of hip and knee ROM were -0.38 [0.05] and -0.26 [0.05], respectively. A higher BMI resulted in lower hip and knee ROM. BMI was also directly associated with prevalent diabetes (0.10 [0.05]) and arthritis (0.17 [0.05]). However, after adjustment for BMI, diabetes and arthritis did not have direct independent associations with either hip or knee ROM. BMI was also indirectly associated with knee, but not hip, ROM through paths including lower-leg pain, pain intensity, and neurosensory impairments. Diabetes had an indirect association with hip, but not knee ROM, through a path including peripheral vascular disease. In conclusion, BMI is a primary direct determinant of hip and knee ROM. The paths by which diabetes and arthritis lead to physical disability may be mediated, in part, at the level of impairment by BMI's association with joint range of motion. Interventions designed to decrease the impact of diabetes and arthritis on disability should track changes in BMI and joint ROM to measure the paths that account for the intervention's success. The observed associations suggest that interventions targeted to decrease BMI itself may lead to improved function in part through improved joint ROM.

Hyperhomocysteinaemia is not related to risk of distal somatic polyneuropathy: the Hoorn Study

OBJECTIVE

Distal somatic polyneuropathy is a major contributing factor in the pathogenesis of chronic foot infections and ulcers, and may lead to lower limb amputations. Both metabolic and vascular abnormalities may contribute to the development of impaired nerve function. We therefore assessed the association between hyperhomocysteinaemia, a risk factor for cardiovascular disease, and polyneuropathy.

DESIGN, SETTING AND SUBJECTS

We studied an age-, sex- and glucose-tolerance-stratified random sample of a 50- to 75-year-old general Caucasian population in the Hoorn Study (N = 629). Any polyneuropathy (N = 95) was defined as the absence of at least two of the three following sensory modalities or reflexes of either foot: light touch sense, ankle reflex and vibration sensation. Definite polyneuropathy (N = 25) was present if, in addition, the vibration perception threshold of the right big toe was abnormal.

RESULTS

The prevalence of any polyneuropathy was 12.4% (33 of 266) in subjects with normal glucose tolerance (NGT), 12.6% (21 of 167) in those with impaired glucose tolerance (IGT), and 25.3% (41 of 162) in those with type 2 diabetes. The prevalence of definite polyneuropathy was 2.6% (7 of 266) in subjects with NGT, 2.4% (4 of 167) in those with IGT and 8.7% (14 of 161) in type 2 diabetic subjects. Polyneuropathy was associated with known risk factors such as diabetes, hyperglycaemia and body height. After adjustment for age, sex, HbA1c and hypertension, the odds ratio (95% CI) for any polyneuropathy per 5 micromol L-1 (about 1 SD) serum total homocysteine increment was 1.00 (0.72-1.39). After adjustment for age and sex, it was 0.62 (0.21-1.89) for definite polyneuropathy.

CONCLUSION

Although a weak relation (as judged from the confidence intervals) cannot be excluded, we conclude that hyperhomocysteinaemia is probably not related to risk of distal somatic polyneuropathy.

Painful diabetic neuropathy

Chronic painful diabetic neuropathy causes symptoms that can last for many years and severely impair the quality of life of affected patients. This review describes the epidemiology, pathophysiology and treatment of chronic neuropathic pain. Particular emphasis is placed on a comprehensive review of the management of painful symptoms through a detailed review of the published literature using a variety of databases particularly Medline and EMBASE.

Diabetic neuropathies: features and mechanisms

Diabetic neuropathies include both focal neuropathies and diffuse polyneuropathy. Polyneuropathy, the most common of the diabetic neuropathies excluding focal entrapment, has not yet been explained by a single disease mechanism despite intensive investigation. A number of abnormalities appear to cascade into a 'vicious cycle' of progressive microvascular disease associated with motor, sensory and autonomic fiber loss. These abnormalities include excessive polyol (sugar alcohol) flux through the aldose reductase pathway, functional and structural alterations of nerve microvessels, nerve and ganglia hypoxia, oxidative stress, nonspecific glycosylation of axon and microvessel proteins, and impairment in the elaboration of trophic factors critical for peripheral nerves and their ganglia. While an initiating role for nerve ischemia in the development of polyneuropathy has been proposed, the evidence for it can be questioned. The role of sensory and autonomic ganglia in the development of polyneuropathy has had relatively less attention despite the possibility that they may be vulnerable to a variety of insults, particularly neurotrophin deficiency. Superimposed on the deficits of polyneuropathy is the failure of diabetic nerves to regenerate as effectively as nondiabetics. Polyneuropathy has not yet yielded to specific forms of treatment but a variety of new trials addressing plausible hypotheses have been initiated. This review will summarize some of the clinical, pathological and experimental work applied toward understanding human diabetic neuropathy and will emphasize ideas on pathogenesis.

Risks for sensorimotor peripheral neuropathy and autonomic neuropathy in non-insulin-dependent diabetes mellitus (NIDDM)

Identification of risk factors for development of diabetic sensorimotor peripheral neuropathy (DSPN) and diabetic autonomic neuropathy (DNA) may help to prevent or modify these complications. The ABCD Trial, a prospective study of diabetic complications, has identified risk factors of the presence and staging of peripheral neuropathy based on neurological symptom scores, neurological disability scores, autonomic function testing and quantitative sensory examination. DSPN is independently associated with diabetes duration [odds ratio (OR) = 1.5 per 10 years], body weight (OR = 1.1 per 5 kg), age (OR = 1.8 per 10 years), retinopathy (OR = 2.3), overt albuminuria (OR = 2.5), height (OR = 1.2 per 10 cm), duration of hypertension (OR = 1.1 per 10 years), insulin use (OR = 1.4), and race/ethnicity [African American vs. non-Hispanic white (OR = 0.4) and Hispanic vs. non-Hispanic white (OR = 0.8)]. DAN is independently associated with diabetes duration (OR = 1.2 per 10 years), body weight (OR = 1.1 per 5 kg), glycosylated hemoglobin (OR = 1.1 per 2.5%), overt albuminuria (OR = 1.6), and retinopathy (OR = 1.8).

Do tissue plasminogen activator-plasminogen activator inhibitor-1 complexes relate to the complications of insulin-dependent diabetes mellitus? Pittsburgh Epidemiology of Diabetes Complications Study

The purpose of this study was to examine the potential relationship of tissue plasminogen activator-plasminogen activator inhibitor-1 (tPA-PAI-1) complexes and diabetic complications in individuals with insulin-dependent diabetes mellitus (IDDM). To address this issue, data from the third follow-up visit of participants in the Epidemiology of Diabetes Complications (EDC) study were examined. There were 454 participants, aged 32 +/- 8 years, with duration of IDDM of 23 +/- 8 years. Higher levels of tPA-PAI-1 complexes were seen for both men and women with IDDM complications. Specifically, statistically significant differences were seen in men with neuropathy (1.81 +/- 0.9 versus 1.42 +/- 0.8 ng/mL, p < 0.01), microalbuminuria (1.77 +/- 1.1 versus 1.35 +/- 0.6 ng/mL, p < 0.01), retinopathy (1.67 +/- 0.9 versus 1.43 +/- 0.8 ng/mL, p < 0.05), and lower extremity arterial disease (1.93 +/- 0.7 versus 1.50 +/- 0.9 ng/mL, p < 0.05) versus men without the particular complication. In women, higher complex levels were shown for those with retinopathy (1.51 +/- 0.8 versus 1.29 +/- 1.1 ng/mL, p < 0.01). Potential mechanisms for the relationship of higher complex levels and diabetic complications include an altered fibrinolytic response and/or insulin resistance. Because the results are cross sectional, it cannot be established whether the higher concentration of complexes is a result of the presence of complications or are antecedent. Prospective follow-up will be required to determine if tPA-PAI-1 complexes are predictive of the development of IDDM complications.

Restoring lower limb blood flow improves conduction velocity in diabetic patients

Human diabetic peripheral neuropathy is believed to have, at least in part, a microvascular basis. This study was designed to examine the effects of restoration of arterial blood supply on peripheral nerve function in six non-insulin-dependent diabetic patients with peripheral occlusive vascular disease. In the revascularised legs, transcutaneous oxygen increased from a median 37.5 (28.5-45.7 interquartile range) mmHg to 55.5 (53.5-62.5) mmHg, p = 0.036, mean increase 20.2 (14.8-25.6, 95% confidence intervals(CI) mmHg. This was accompanied by a significant improvement in peroneal motor nerve conduction velocity from 31.7 (26.5-36.3) m/s to 33.5 (32.9-39.4) m/s, p = 0.04, mean increase 4.7 (1.7-7.7, 95% CI) m/s. There was no significant change in transcutaneous oxygen or peroneal nerve motor conduction velocity in the contralateral control limbs. This improvement in conduction velocity with improved tissue oxygenation suggests that studies of agents which might indirectly bring about improvements in microvascular blood flow should be urgently considered.

Prevalence and forms of neuropathic morbidity in 800 diabetics

We prospectively determined the prevalence of morbidity from the various forms of diabetic neuropathy over one year in a population of 800 patients with diabetes mellitus (336 type 1, 464 type 2 DM). Symptoms documented were: pain/paraesthesia in the feet, loss of feeling and the restless legs syndrome. We also documented the prevalence of: neuropathic ulcers, amyotrophy, foot drop, and oculomotor palsy. Autonomic symptoms documented were: impotence, postural hypotension and diarrhoea. The only symptoms reported by 100 non-diabetic control subjects were: loss of feeling in 2% and restless legs syndrome in 7%. In the diabetics; pain/paraesthesia was present in 13%, feeling loss in 7% and neuropathic ulcers in 2%. The prevalence of Diabetic amyotrophy (proximal femoral neuropathy) was 0.8%, oculomotor palsy 0.1% and peroneal nerve palsy 0.1%. Erectile impotence was present in 20%, symptomatic postural hypotension in 1% and diabetic diarrhoea in 1%. Overall; 22.9% of the population was afflicted by one or more problems resulting from neuropathy. Neuropathy was associated with older age (p < 0.001), and serious retinopathy (p < 0.001) in both groups of diabetics and with duration of diabetes, proteinuria (p < 0.02), hypertension (p < 0.01) and ischaemic heart disease (p < 0.02) in type 1 diabetics.

The effects of age and diabetes mellitus on nerve function

OBJECTIVE

This project evaluated the association of age and vibratory thresholds (assessment modality of large sensory nerve fibers) in subjects with and without diabetes mellitus.

DESIGN

Cross-sectional study.

SETTING

Medical Research Institute of Delaware.

PARTICIPANTS

Individuals with non-insulin-dependent diabetes mellitus and non-diabetic control subjects.

MEASUREMENTS

Vibratory thresholds were examined in four age groups (ie, < 45 yrs, 45-54 yrs, 55-64 yrs, > or = 65 yrs). The independent association of age, duration of diabetes, height, gender, glycemic control, and smoking history were analyzed in terms of their relationship to vibratory thresholds.

MAIN RESULTS

Vibratory thresholds increased with age for both control and diabetic subjects. Comparing controls with diabetic subjects in the same age categorizes revealed significant differences for vibratory thresholds only in the > or = 65 year old age group. Modeling with vibratory thresholds as the dependent variable showed that age and male gender were independently associated with vibratory thresholds for the controls and explained the majority of the variability (R2 = 0.79). Age, duration of diabetes, and height were independently associated with vibratory thresholds for the diabetic subjects but explained much less of the variability (R2 = 0.39).

CONCLUSIONS

The results suggest an acceleration of the natural aging process for large sensory nerve fiber function in diabetic subjects. Thus, young diabetic subjects may be at a risk of lower extremity complications as a result of injuries similar to that older non-diabetic individuals.

Overt diabetic neuropathy: repair of axo-glial dysjunction and axonal atrophy by aldose reductase inhibition and its correlation to improvement in nerve conduction velocity

Clinically overt diabetic neuropathy is characterized by neuroanatomical changes of the node of Ranvier and myelinated axons, and by decreased nerve conduction velocity. Sural nerve biopsies were obtained from 16 neuropathic diabetic patients participating in a 12-month randomized, placebo-controlled, double-blind clinical trial of the aldose reductase inhibitor sorbinil. One sural nerve biopsy was obtained at baseline and a second biopsy at the termination of the trial. Ten sorbinil-treated patients showed significant improvement in axo-glial dysjunction, a characteristic lesion of the node of Ranvier. Axonal atrophy assessed by three independent morphometric techniques also exhibited significant recovery in the sorbinil-treated patients. No change was demonstrated in any of these structural parameters in six placebo-treated patients. The improvement in sural nerve conduction velocity in sorbinil-treated patients correlated with the product of the quantitative improvements in axo-glial dysjunction and axonal atrophy. We conclude that the activated polyol-pathway plays a sustaining role in nerve fibre damage in diabetic neuropathy, and that structural lesions such as axo-glial dysjunction and axonal atrophy which are reversible following intervention with an aldose reductase inhibitor, constitute the morphological basis for nerve conduction slowing in overt diabetic neuropathy.

A multicentre study of the prevalence of diabetic peripheral neuropathy in the United Kingdom hospital clinic population

A cross-sectional multicentre study of randomly selected diabetic patients was performed using a standardised questionnaire and examination, to establish the prevalence of peripheral neuropathy in patients attending 118 hospital diabetes clinics in the UK. Vibration perception threshold was performed in two centres to compare with the clinical scoring systems. A total of 6487 diabetic patients were studied. 53.9% male, median age 59 years (range 18-90 years). 37.4% Type 1 (insulin-dependent) diabetes mellitus, with a median duration of diabetes 8 years (0-62 years). The overall prevalence of neuropathy was 28.5% (27.4-29.6%) (95% confidence interval) in this population. The prevalence in Type 1 diabetic patients was 22.7% (21.0-24.4%) and in Type 2 (non-insulin-dependent) diabetic patients it was 32.1% (30.6-33.6%). The prevalence of diabetic peripheral neuropathy increased with age, from 5% (3.1-6.9%) in the 20-29 year age group to 44.2% (41.1-47.3%) in the 70-79 year age group. Neuropathy was associated with duration of diabetes, and was present in 20.8% (19.1-22.5%) of patients with diabetes duration less than 5 years and in 36.8% (34.9-38.7%) of those with diabetes duration greater than 10 years. Mean vibration perception threshold measured at the great toe was 21.1 +/- 13.5 SD volts and correlated with the neuropathy disability score, r = 0.8 p < 0.001. In conclusion, diabetic peripheral neuropathy is a common complication associated with diabetes. It increases with both age and duration of diabetes, until it is present in more than 50% of Type 2 diabetic patients aged over 60 years.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship between myoinositol influx and lipids in diabetic neuropathy

Diabetic neuropathy is associated with abnormalities in lipid metabolism and has been postulated to be associated with abnormal myoinositol metabolism. Leucocyte myoinositol influx was measured using a triple isotope method in long-standing type 1 (insulin-dependent) diabetic patients with and without diabetic neuropathy and in a group of matched controls. No differences in fasting lipid, glucose concentrations or glycated haemoglobin were found in the diabetic groups. Myoinositol influx was significantly but negatively correlated with the serum very low density lipoprotein (VLDL) cholesterol concentration in patients with and without neuropathy but not in the controls. The VLDL cholesterol concentration also correlated negatively with the transporter Km (Rs = -0.87, P < 0.005, neuropathic group only) and Vmax (Rs = -0.93, P < 0.001, neuropathic group; Rs = -0.59, P < 0.05, non-neuropathic group). Myoinositol influx correlated with the glycated haemoglobin only in the diabetic patients without neuropathy. The lipid relationships in diabetic subjects were independent of glucose control, which suggests that myoinositol influx mechanisms represent another transporter affected by intracellular lipid metabolism. The control of VLDL metabolism by fibrates could offer a method for reducing the progression of diabetic neuropathy.

Nerve function and its determinants in patients with newly-diagnosed type 2 (non-insulin-dependent) diabetes mellitus and in control subjects--a 5-year follow-up

In order to assess the changes in nerve function 5 years after the diagnosis of diabetes mellitus and the determinants of progression of neuropathy, we studied 113 Type 2 (non-insulin-dependent) diabetic patients and 127 non-diabetic control subjects. Motor and sensory nerve conduction velocities were measured at the time of diagnosis of diabetes and 5 years later. At both examinations conduction velocities and response amplitudes were lower in diabetic patients than in control subjects. During the follow-up sural nerve conduction was impaired in both diabetic and control subjects, but, in general, changes in neurophysiological parameters were slight and inconsistent. In 12 diabetic patients nerve function deteriorated significantly during the follow-up. These patients had higher glycaemic indices at both examinations and lower baseline blood pressure levels as compared to the rest of the diabetic patients. No differences between these patient groups were found in other baseline risk factors (age, obesity, use of alcohol, smoking, serum insulin levels, albuminuria, lipids). In conclusion, Type 2 diabetic patients have disturbed nerve function at the time of diagnosis, but neurophysiological impairment during the next 5 years is on the average slight. Poor glycaemic control seems to be the most important risk factor in the deterioration of nerve function in these patients.

Problems with gait and posture in neuropathic patients with insulin-dependent diabetes mellitus

Peripheral neuropathy secondary to diabetes mellitus is believed to cause postural instability and uncoordinated gait, although this is not well documented. Two groups of patients from the Pittsburgh Epidemiology of Diabetes Complications Study, matched for age and duration of Type 1 diabetes, but with significantly different vibratory sensation thresholds as determined by Vibratron II testing, were therefore surveyed. The mean ages were 32.9 and 31.9 years and durations of diabetes were 22.0 and 18.8 years for the neuropathic and control groups, respectively. Patients provided details of fall injuries, and perception of safety during standing and walking. Multiple linear and logistic regression models were used to account for potentially associated variables such as gender, retinopathy, and duration of diabetes. The neuropathic group had adjusted odds ratios for reported injuries during gait of 15.0 relative to the control group (95% confidence intervals 1.04-216.59). The neuropathic group also reported significantly lower scores (less safe, p = 0.004) than the control group on perceived safety in unusual conditions. It is concluded that peripheral neuropathy has an effect on gait and posture which is clinically significant and that this effect merits further biomechanical study in neuropathic patients.

The prevalence of diabetic distal sensory neuropathy in an English community

The prevalence of lower limb neuropathy was determined in a known diabetic population. From a general population of 97,034 subjects, a total of 1150 diabetic patients were identified of whom 1077 (93.7%) were reviewed. Neuropathy was defined as symptoms plus one abnormal physical finding, or two abnormal physical findings. An age- and sex-matched non-diabetic control group of 480 individuals was also examined by the same single observer. The prevalence of neuropathy was 16.3 (95% CI 14.6-19.0)% in diabetic patients and 2.9 (95% CI 1.4-4.4)% in non-diabetic subjects, yielding a prevalence odds of 6.75 (95% CI 3.87-11.79), p less than 0.001. In Type 1 diabetes, the prevalence was 12.7 (95% CI 8.0-17.6)% and in Type 2 diabetes 17.2 (95% CI 15.9-18.5)%. After adjusting for age, the difference was not significant (odds ratio (OR) 1.60 (95% CI 0.95-2.76)). The prevalence of neuropathy increased with age in diabetic and non-diabetic subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term suppression of postprandial hyperglycaemia with acarbose retards the development of neuropathies in the BB/W-rat

The effect of the alpha-glucosidase inhibitor acarbose on postprandial hyperglycaemia was explored in the spontaneously diabetic BB/W-rat. Acarbose-treatment (5 mg.kg body weight-1.day-1) of diabetic BB/W-rats maintained on small doses of insulin, was associated with a 40% reduction in the 24-h glucose area compared to non-treated diabetic rats. Over a 4 month treatment period this reduction in cumulative hyperglycaemia resulted in a complete prevention of autonomic polyneuropathy as indicated by R-BAR values. The development of somatic polyneuropathy in the BB/W-rat was significantly attenuated by acarbose treatment with a partial prevention of the characteristic nerve conduction velocity slowing during the first 3 months of diabetes, but no longer at 4 months. Characteristic structural abnormalities associated with diabetes in this model, such as axonal atrophy and axo-glial dysjunction, were significantly but only partially prevented in rats treated with acarbose for a diabetes duration of 4 months. These data suggest that postprandial lowering of hyperglycaemia resulting in a decrease in cumulative hyperglycaemia retards the development of diabetic polyneuropathies in the BB/W-rat.

Extensor digitorum brevis in diabetic neuropathy: a controlled evaluation in diabetic patients aged 15-50 years

A reduction in the bulk of the extensor digitorum brevis muscle (EDB) may be a sign of diabetic neuropathy. We devised a semi-quantitative scale (normal, reduced or absent) for assessing the bulk of the EDB muscle, and judged it to be a sign of neuropathy in 375 of 395 diabetic patients aged 15-50 years in the county of Umeå, 79% of whom had Type 1 diabetes mellitus (DM), and in 100 healthy controls. Reduced or absent EDB was significantly more common in patients with Type 1 and Type 2 DM than in controls (44 and 48 vs. 12%; P less than 0.001). In patients with Type 1 DM, reduced or absent EDB was significantly correlated with age, longer duration of DM, smoking, dry feet, and foot ulcers, but not with fallen forefoot arch, hammer toes or callosities. Reduced or absent EDB was also associated with skin and nail lesions, including Melin's shin spots, purpura and yellow toenails, but not with necrobiosis. Sensory thresholds for vibration, perception and pain were all significantly elevated in Type 1 diabetic patients with impaired EDB, compared to Type 1 diabetics with normal EDB. In controls, impaired EDB was only significantly correlated with smoking. We conclude that the EDB test is easy to perform, and may be used to screen for neuropathy in Type 1 diabetic patients.