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

Using Skin Bioengineering to Highlight How Weight and Diabetes Mellitus Modify the Skin in the Lower Limbs of Super-Obese Patients

AIM

To evaluate the distinct contribution of obesity and diabetes (DM) to the skin modification in metabolic diseases.

METHODS

We analysed all patients admitted for bariatric surgery in our hospital with BMI between 38 and 47 kg/m², with (Group 1) or without (Group 2) DM and compared them with a group of nonobese diabetic patients (Group 3) and healthy volunteers (Group 4). The following features were evaluated: hardness, temperature, hydration and thickness alongside with anthropometric measures of foot and leg.

RESULTS

For the general characteristics, patients differed in age and body mass index. As predictable all circumferences (dorsal foot, sovramalleolar and under the knee) were significantly higher in obese with no differences depending on DM (all parameters: p<0.01 in Group 1 and Group 2 vs Group 3 and Group 4). Skin temperature was significantly higher in all obese, irrespectively from the presence of DM (1st metatarsal head: p=0.02 Group 1 and Group 2 vs Group 3 and Group 4; 5th metatarsal head: p<0.01 in Group 1 and Group 2 vs Group 3 and Group 4). Skin hydration score showed increased anhydrosis in both diabetics and severe obesity (p<0.01 in Group 1 and Group 3 vs Group 2 and Group 4). Increase in thickness of skin and subcutaneous tissues was observed (at heel: p<0.01 in Group 1 and Group 2 vs Group 3 and Group 4 and under the scaphoid p=0.03 Group 1 and Group 2 vs Group 3 and Group 4) and plantar fascia (in both regions p=0.02 Group 1 and Group 2 vs Group 3 and Group 4) in all obese patients, with or without DM.

CONCLUSION

Severe obesity significantly affects both shape and structure of the foot, possibly exposing these patients to a higher risk of biomechanical stress. On such a background DM, modifying skin hydration and protective mechanisms exerts a synergistic role further increasing the risk of trauma and ulcers.

Quantitative assessment of early biomechanical modifications in diabetic foot patients: the role of foot kinematics and step width

BACKGROUND

Forefoot ulcers (FU) are one of the most disabling and relevant chronic complications of diabetes mellitus (DM). In recent years there is emerging awareness that a better understanding of the biomechanical factors underlying the diabetic ulcer could lead to improve the management of the disease, with significant socio-economic impacts. Our purpose was to try to detect early biomechanical factors associated with disease progression.

METHODS

Thirty subjects (M/F: 22/8; mean age ± SD: 61,84 ± 10 years) with diagnosis of type II DM were included. The participants were divided into 3 groups (10 subjects per group) according to the stage of evolution of the disease: Group 1, subjects with newly diagnosed type II DM, without clinical or instrumental diabetic peripheral neuropathy (DPN) nor FU (group called "DM"); Group 2, with DPN but without FU (group called "DPN"); Group 3, with DPN and FU (group called "DNU"). All subjects underwent 3-D Gait Analysis during walking at self-selected speed, measuring spatio-temporal, kinematic and kinetic parameters and focusing on ankle and foot joints. The comparative analysis of values between groups was performed using 1-way ANOVA. We also investigated group to group differences with Tukey HSD test. The results taken into consideration were those with a significance of P < 0,05. 95 % confidence interval was also calculated.

RESULTS

A progressive and significant trend of reduction of ROM in flexion-extension of the metatarso-phalangeal joint (P = 0.0038) and increasing of step width (P = 0.0265) with the advance of the disease was evident, with a statistically significant difference comparing subjects with recently diagnosed diabetes mellitus and subjects with diabetic neuropathy and foot ulcer (P = 0.0048 for ROM and P = 0.0248 for step width at Tukey's test).

CONCLUSIONS

The results provide evidence that foot segmental kinematics, along with step width, can be proposed as simple and clear indicators of disease progression. This can be the starting point for planning more targeted strategies to prevent the occurrence and the recurrence of a FU in diabetic subjects.

The Effect of Cigarette Smoking on Diabetic Peripheral Neuropathy: A Systematic Review and Meta-Analysis

OBJECTIVE

Studies suggest that smoking may be a risk factor for the development of microvascular complications such as diabetic peripheral neuropathy (DPN). The objective of this study was to assess the relationship between smoking and DPN in persons with type 1 or type 2 diabetes.

RESEARCH DESIGN AND METHODS

A systematic review of the PubMed, Embase, and Cochrane clinical trials databases was conducted for the period from January 1966 to November 2014 for cohort, cross-sectional and case-control studies that assessed the relationship between smoking and DPN. Separate meta-analyses for prospective cohort studies and case-control or cross-sectional studies were performed using random effects models.

RESULTS

Thirty-eight studies (10 prospective cohort and 28 cross-sectional) were included. The prospective cohort studies included 5558 participants without DPN at baseline. During follow-up ranging from 2 to 10 years, 1550 cases of DPN occurred. The pooled unadjusted odds ratio (OR) of developing DPN associated with smoking was 1.26 (95% CI 0.86-1.85; I(2) = 74%; evidence grade: low strength). Stratified analyses of the prospective studies revealed that studies of higher quality and with better levels of adjustment and longer follow-up showed a significant positive association between smoking and DPN, with less heterogeneity. The cross-sectional studies included 27,594 participants. The pooled OR of DPN associated with smoking was 1.42 (95% CI 1.21-1.65; I(2) = 65%; evidence grade: low strength). There was no evidence of publication bias.

CONCLUSIONS

Smoking may be associated with an increased risk of DPN in persons with diabetes. Further studies are needed to test whether this association is causal and whether smoking cessation reduces the risk of DPN in adults with diabetes.

Pathophysiology of diabetic erectile dysfunction: potential contribution of vasa nervorum and advanced glycation endproducts

Erectile dysfunction (ED) due to diabetes mellitus remains difficult to treat medically despite advances in pharmacotherapeutic approaches in the field. This unmet need has resulted in a recent re-focus on the pathophysiology, in order to understand the cellular and molecular mechanisms leading to ED in diabetes. Diabetes-induced ED is often resistant to PDE5 inhibitor treatment, thus there is a need to discover targets that may lead to novel approaches for a successful treatment. The aim of this brief review is to update the reader in some of the latest development on that front, with a particular focus on the role of impaired neuronal blood flow and the formation of advanced glycation endproducts.

Update on the management of diabetic polyneuropathies

The prevalence of diabetic polyneuropathy (DPN) can approach 50% in subjects with longer-duration diabetes. The most common neuropathies are generalized symmetrical chronic sensorimotor polyneuropathy and autonomic neuropathy. It is important to recognize that 50% of subjects with DPN may have no symptoms and only careful clinical examination may reveal the diagnosis. DPN, especially painful diabetic peripheral neuropathy, is associated with poor quality of life. Although there is a better understanding of the pathophysiology of DPN and the mechanisms of pain, treatment remains challenging and is limited by variable efficacy and side effects of therapies. Intensification of glycemic control remains the cornerstone for the prevention or delay of DPN but optimization of other traditional cardiovascular risk factors may also be of benefit. The management of DPN relies on its early recognition and needs to be individually based on comorbidities and tolerability to medications. To date, most pharmacological strategies focus upon symptom control. In the management of pain, tricyclic antidepressants, selective serotonin noradrenaline reuptake inhibitors, and anticonvulsants alone or in combination are current first-line therapies followed by use of opiates. Topical agents may offer symptomatic relief in some patients. Disease-modifying agents are still in development and to date, antioxidant α-lipoic acid has shown the most promising effect. Further development and testing of therapies based upon improved understanding of the complex pathophysiology of this common and disabling complication is urgently required.

Treatment of diabetic sensory polyneuropathy

OPINION STATEMENT

No current disease-modifying treatments have been shown definitively in randomized clinical trials to reduce or reverse diabetic sensory polyneuropathy (DSP). It is increasingly recognized that individuals with "prediabetes" or impaired glucose regulation can already have a "small-fiber" neuropathy, or mild DSP, in which sensory axons of both small and larger diameter are damaged. Small-fiber neuropathy is frequently associated with pain, and these patients may present to a neurologist for evaluation before the underlying glucose dysregulation has been diagnosed. It is important to identify these individuals, because aggressive diabetic control and lifestyle interventions can delay the onset of diabetes and may reverse small-fiber neuropathy associated with early diabetes mellitus. Although treatment currently focuses on pain associated with DSP, attention should be paid to potential risk factors for neuropathy. For example, glycemic control and hyperlipidemia should be improved with diet, exercise, and medications. Hypertension that is a risk marker for more severe neuropathy should be treated. Angiotensin-converting enzyme inhibitors or angiotensin-receptor blockers not only treat hypertension but also may directly reduce the progression of neuropathy. Class I or II clinical studies support the use of sodium valproate, pregabalin, duloxetine, amitriptyline, gabapentin, venlafaxine, opioids, and topical capsaicin in treating diabetic neuropathic pain. Pregabalin and gabapentin are relatively well tolerated and have few medication interactions. Sodium valproate has been shown to be effective but is not recommended for use in women of childbearing potential, and patients must be monitored for hepatotoxicity and thrombocytopenia. Tricyclic antidepressants such as amitriptyline are often used for nocturnal pain but require caution in the elderly or anyone with cardiac disease. Venlafaxine and duloxetine successfully treat neuropathic pain independently of their effect on depression. Opioid medications are associated with a high rate of adverse effects but with careful monitoring, they can be effective in treating resistant neuropathic pain. Capsaicin is an effective topical treatment that lacks systemic side effects. The lidocaine patch is effective in relieving pain associated with postherpetic neuralgia, but only class III evidence supports its use for diabetic neuropathic pain. No current Class I or II studies support other treatment modalities.

Reliability of quantitative sudomotor axon reflex testing and quantitative sensory testing in neuropathy of impaired glucose regulation

Reproducible neurophysiologic testing paradigms are critical for multicenter studies of neuropathy associated with impaired glucose regulation (IGR), yet the best methodologies and endpoints remain to be established. This study evaluates the reproducibility of neurophysiologic tests within a multicenter research setting. Twenty-three participants with neuropathy and IGR were recruited from two study sites. The reproducibility of quantitative sudomotor axon reflex test (QSART) and quantitative sensory test (QST) (using the CASE IV system) was determined in a subset of patients at two sessions, and it was calculated from intraclass correlation coefficients (ICCs). QST (cold detection threshold: ICC=0.80; vibration detection threshold: ICC=0.75) was more reproducible than QSART (ICC foot=0.52). The performance of multiple tests in one setting did not improve reproducibility of QST. QST reproducibility in our IGR patients was similar to reports of other studies. QSART reproducibility was significantly lower than QST. In this group of patients, the reproducibility of QSART was unacceptable for use as a secondary endpoint measure in clinical research trials.

Standing balance and trunk position sense in impaired glucose tolerance (IGT)-related peripheral neuropathy

Type 2 diabetes mellitus (T2DM) and pre-diabetes or impaired glucose tolerance (IGT) affect a large segment of the population. Peripheral neuropathy (PN) is a common complication of T2DM, leading to sensory and motor deficits. While T2DM-related PN often results in balance- and mobility-related dysfunction which manifests as gait instability and falls, little is known about balance capabilities in patients who have evidence of PN related to IGT (IGT-PN). We evaluated patients with IGT-PN on commonly-used clinical balance and mobility tests as well as a new test of trunk position sense and balance impairment, trunk repositioning errors (TREs). Eight participants aged 50-72 years with IGT-PN, and eight age- and gender-matched controls underwent balance, mobility and trunk repositioning accuracy tests at a university neurology clinic and mobility research laboratory. Compared to controls, IGT-PN participants had as much as twice the magnitude of TREs and stood approximately half as long on the single leg balance test. People with IGT-PN exhibit deficits in standing balance and trunk position sense. Furthermore, there was a significant association between performance on commonly-used clinical balance and mobility tests, and electrophysiological and clinical measures of neuropathy in IGT-PN participants. Because IGT-related neuropathy represents the earliest stage of diabetic neuropathy, deficits in IGT-PN participants highlight the importance of early screening in the dysglycemic process for neuropathy and associated balance deficits.

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

BACKGROUND

Peripheral arterial disease (PAD) and peripheral neuropathy (PN) are serious complications of diabetes, but early detection and intervention may reduce this morbidity. The degree to which PAD and PN develop before diabetes diagnosis has not been established among a representative sample of U.S. adults.

OBJECTIVE

To compare the prevalence of lower extremity diseases (LEDs) among U.S. adults aged 40 or older with previously diagnosed diabetes, undiagnosed diabetes, impaired fasting glucose, and normal glucose levels.

RESEARCH DESIGN AND METHODS

We analyzed cross-sectional data of a nationally representative sample of 3607 U.S. adults from the 1999-2004 National Health and Nutrition Examination Surveys (NHANES). Subjects were divided into four groups on the basis of their fasting plasma glucose (FPG) levels and interview responses: normal glucose levels (FPG<100mg/dl), impaired fasting glucose (IFG; FPG 100-125 mg/dl), undiagnosed diabetes (FPG> or =126 and no self-reported diabetes), and diagnosed diabetes. PN was assessed by monofilament testing at three sites on each foot and defined as > or =1 insensate area. PAD was defined as an ankle-brachial blood pressure index <0.9. Any LED was defined as the presence of PAD or PN or a history of non-healing ulcer or amputation.

RESULTS

The prevalence of PN was lowest among persons with normal glucose (10.5%) and IFG (11.9%) and highest among those with undiagnosed (16.6%) and diagnosed diabetes (19.4%). PAD prevalence was also lowest among persons with normal glucose (3.9%), similar among those with IFG (5.4%), and significantly higher among those with undiagnosed (9.2%) and diagnosed diabetes (7.5%). Any LED was present in about 27% of persons with both undiagnosed diabetes and diagnosed diabetes.

CONCLUSIONS

LED prevalence was nearly as high among persons with previously undiagnosed diabetes as among those with diagnosed diabetes, but it was not appreciably higher among persons with impaired fasting glucose than among those with normal glucose levels. These results suggest that LED detection efforts should be focused on persons with diabetes, including those with undiagnosed diabetes.

Peripheral neuropathy in type 2 diabetes mellitus in Isfahan, Iran: prevalence and risk factors

BACKGROUND

To estimate the prevalence and risk factors of peripheral neuropathy (PN) in people with type 2 diabetes mellitus.

METHODS

A total of 810 patients with type 2 diabetes (289 men and 521 women) from Isfahan Endocrinology and Metabolism Research Centre outpatient clinics, Iran, were examined. Part of examination included an assessment of neurological function including neuropathic symptoms and physical signs and nerve conduction velocity.

RESULTS

The prevalence of PN was 75.1% (95% confidence interval 72.1, 78.0). PN was associated with age, proteinuria, and duration of diabetes, insulin-treatment, and presence of any retinopathy and ischaemic heart disease (IHD). The age-adjusted prevalence rate of PN was 78% higher among patients with IHD, 64% higher among patients with any retinopathy, 66% higher among insulin-treated type 2 diabetes, and it was greater with duration of diabetes. Using a stepwise binary logistic regression model, age, duration of diabetes and proteinuria were significant independent predictors of PN.

CONCLUSION

Peripheral neuropathy is a common complication in this population of Iranian type 2 diabetic patients. It increases with age, duration of diabetes and proteinuria.

Electrophysiological findings of peripheral neuropathy in newly diagnosed type II diabetes mellitus

This study was aimed at assessing the electrophysiological signs of peripheral neuropathy in diabetes mellitus (DM) type II patients at diagnosis. Nerve conduction studies (NCS) of median, ulnar, peroneal, tibial and sural nerves were performed in 39 newly diagnosed DM subjects and compared to those of 40 healthy controls. Metabolic indices were also investigated. Electrophysiological alterations were found in 32 (82%) of the DM patients, and more than half of them (62.2%) showed multiple (two to five) abnormal parameters. Because most of the subjects (84.4%) had from two to five nerves involved, these alterations were widespread in the seven nerves evaluated. Forty-two percent of the patients had NCS alterations suggestive of distal median mononeuropathy, implying that metabolic factors in DM make the median nerve more susceptible to focal entrapment. A reduced sensory nerve action potential (SNAP) amplitude was observed in the median nerve in 70% of the patients, in the ulnar in 69% and in the sural nerve only in 22%. In the presence of a decrease in the SNAP amplitude of the ulnar or median nerve, the SNAP amplitude of the sural nerve was normal in 82 or 80% of the subjects, respectively. This finding may be in keeping with a distal involvement of the sensory fibres, as explored by routine median or ulnar NCS. No correlation was found between metabolic indices and NCS parameters. In conclusion, a high percentage of newly diagnosed DM patients show signs of neuropathy, and upper limb nerve sensory NCS seem to be more sensitive in detecting it than lower limb NCS.

Cardiac autonomic neuropathy in diabetic patients: influence of diabetes duration, obesity, and microangiopathic complications--the French multicenter study

The current study sought to examine in a large series of diabetic patients the prevalence of symptoms of autonomic neuropathy and subclinical cardiac autonomic neuropathy (CAN) and their determinants, particularly the influence of diabetes duration, obesity, and microangiopathic complications. Three hundred ninety-six patients, 245 type 1 and 151 type 2, were recruited in 7 French departments of diabetology. CAN was detected by measuring heart rate variability during 3 standardized tests: deep-breathing, Valsalva, and lying-to-standing tests. At least 24.5% of the patients had one or more symptoms suggesting overt autonomic neuropathy. They were older than those free of dysautonomic symptom (P<.001). The deep-breathing test correlated negatively with body mass index (BMI) in type 2 diabetic patients (P<.0001). In the whole population, the deep-breathing and Valsalva tests correlated negatively with diabetes duration (P=.0004 and.019, respectively) and the log urinary albumin/creatinine ratio (P<.002 and.001, respectively). The prevalence of CAN (51%) was higher than the prevalence of other diabetic complications. The rate of moderate and severe CAN (defined by 2 or 3 abnormal CAN function tests) was higher in type 1 than in type 2 diabetic patients (P=.031). It correlated with diabetes duration (P=.026) and was higher in the patients with retinopathy than in those without (P=.035). Among type 2 diabetic patients, the prevalence of CAN was higher in the obese ones (P=.033); in a logistic regression taking age, diabetes duration, and obesity as independent variables, CAN was associated independently with obesity (P=.034). Mild or moderate CAN was found in 33.8% and 13.0% of the 80 patients with diabetes duration less than 18 months. We conclude that CAN is found early in the course of diabetes and should be considered as a prognostic marker of microangiopathic complications. Obesity could be involved in the impairment of CAN function in type 2 diabetics and body weight control could provide an approach to reducing neuropathic complications.

Foot complications in Type 2 diabetes: an Australian population-based study

AIMS

To determine the prevalence and risk factors for neuropathy and peripheral vascular disease (PVD) in the Australian diabetic population and identify those at high risk of foot ulceration.

METHODS

The Australian Diabetes Obesity and Lifestyle study included 11 247 adults aged >or= 25 years in 42 randomly selected areas of Australia. Neuropathy and PVD were assessed in participants identified as having diabetes (based on self report and oral glucose tolerance test), impaired fasting glucose, impaired glucose tolerance and in a random sample with normal glucose tolerance (total n = 2436).

RESULTS

The prevalence of peripheral neuropathy was 13.1% in those with known diabetes (KDM) and 7.1% in those with newly diagnosed (NDM). The prevalence of PVD was 13.9% in KDM and 6.9% in NDM. Of those with diabetes, 19.6% were at risk of foot ulceration. Independent risk factors for peripheral neuropathy were diabetes duration (odds ratio (95% CI) 1.73 (1.33-2.28) per 10 years), height (1.42 (1.08-1.88) per 10 cm), age (2.57 (1.94-3.40) per 10 years) and uric acid (1.59 (1.21-2.09) per 0.1 mmol/l). Risk factors for PVD were diabetes duration (1.64 (1.25-2.16) per 10 years), age (2.45 (1.86-3.22) per 10 years), smoking (2.07 (1.00-4.28)), uric acid (1.03 (1.00-1.06) per 0.1 mmol/l) and urinary albumin/creatinine ratio (1.11 (1.01-1.21) per 1 mg/mmol).

CONCLUSIONS

The prevalence of neuropathy and PVD was lower in this population than has been reported in other populations. This may reflect differences in sampling methods between community and hospital-based populations. Nevertheless, a substantial proportion of the diabetic population had risk factors for foot ulceration.

Diabetic neuropathy in elderly Type 2 diabetic patients: effects of insulin treatment

OBJECTIVES

To study the occurrence of diabetic neuropathy and the effect of insulin treatment in elderly Type 2 diabetic patients.

MATERIAL AND METHODS

In 38 patients and 20 controls symptoms and neurophysiological examinations including electroneurography, vibration perception and temperature discrimination thresholds were investigated. Patients were randomized to insulin (n = 18) or sulfonylurea (n = 16) treatment and were re-investigated after 1 year.

RESULTS

Neuropathy was present in 21/38 patients (56%). It was asymptomatic in 17/38 (45%) and symptomatic in 4/38 (11%). The occurrence of neuropathy was less common in healthy controls, 3/20 (15%) (P < 0.01). Temperature discrimination thresholds was the test that most often revealed pathology. The metabolic control after 1 year was significantly improved in the insulin treated group and unchanged in the sulfonylurea treated group. There were no changes as regards occurrence of neuropathy between or within the two treatment groups after 1 year.

CONCLUSION

Diabetic neuropathy is common among elderly Type 2 diabetic patients. It is mostly asymptomatic. Improvement was not seen after 1 year of insulin treatment.

Profile of neurological problems in diabetes mellitus retrospective analysis of data from 1294 patients

Data from 1294 patients with diabetes mellitus admitted to the Endocrinology Department of the Institute of Medical Sciences, Srinagar, Kashmir, from 1986 to 1994, were analyzed for frequency of various neurological problems. Of 1294 patients, 46.29% had clinical evidence of one or more neurological problems. The frequency of neurological problems was significantly more in patients with type II diabetes mellitus (P<0.001). Predominant neurological problems included peripheral neuropathy (96.66%), stroke (5.51%), Parkinsonism (1.50%), seizure disorder (1.17%) and dementia (1%). Mean (+/- SD) age of patients with neurological problems was significantly more (P<0.001) than those without neurological problems (52.07+/- 9.52 versus 47.45+/- 12.87 years for type II diabetes mellitus; 26.73+/- 8.40 versus 18.0+/- 3.62 for type I diabetes mellitus). Mean duration of diabetes in patients with neurological problems was significantly more than those without neurological problems (6.70+/- 6.04 versus 3.95+/- 4.22 years for type II diabetes mellitus; 5.63+/- 3.67 versus 1.89+/- 2.57 for type I diabetes mellitus). At the time of admission, fasting blood glucose was lower in patients without neurological problems as compared to patients with problems (9.08+/- 2.22 versus 11.05+/- 4.91 mmol/L for type II diabetes mellitus; 9.44+/- 2.80 versus 13.01+/- 5.01 mmol/L for type I diabetes mellitus; P7lt;0.001).

Natural history of peripheral neuropathy in patients with non-insulin-dependent diabetes mellitus

BACKGROUND

There is little information on the incidence and natural history of neuropathy in patients with non-insulin-dependent diabetes mellitus (NIDDM).

METHODS

We studied patients with newly diagnosed NIDDM and control subjects both at base line and 5 and 10 years later. Polyneuropathy was diagnosed on the basis of clinical criteria (pain and paresthesias) and electrodiagnostic studies (nerve conduction velocity and response-amplitude values). We investigated the relation between metabolic variables (results of oral glucose-tolerance tests, serum lipid and insulin concentrations, and glycosylated hemoglobin values) and the development of polyneuropathy.

RESULTS

In 10 years, 36 patients with NIDDM and 8 control subjects died; 86 patients and 121 control subjects completed the study. When the study ended, 18 percent of the patients were being treated only with diet, 59 percent with oral hypoglycemic drugs alone, 12 percent with insulin alone, and 11 percent with both insulin and oral hypoglycemic agents. At base line the prevalence of definite or probable polyneuropathy among the patients with NIDDM was 8.3 percent, as compared with 2.1 percent among the control subjects. These values 10 years later were 41.9 percent and 5.8 percent, respectively. The number of patients with NIDDM who had nerve-conduction abnormalities in the legs and feet increased from 8.3 percent at base line to 16.7 percent after 5 years and to 41.9 percent after 10 years. The decrease in sensory and motor amplitudes, indicating axonal destruction, was more pronounced than the slowing of the nerve conduction velocities, which indicates demyelination. Among the patients with NIDDM, those with polyneuropathy had poorer glycemic control than those without. Low serum insulin concentrations before and after the oral administration of glucose were associated with the development of polyneuropathy, regardless of the degree of glycemia.

CONCLUSIONS

The prevalence of polyneuropathy among patients with NIDDM increases with time, and the increase may be greater in patients with hypoinsulinemia.

The efficacy of aldose reductase inhibitors in the management of diabetic complications. Comparison with intensive insulin treatment and pancreatic transplantation

Recently, aldose reductase inhibitors (ARIs) have been registered in several countries for the improvement of glycaemic control. However, their efficacy is still controversial. ARIs inhibit the enhanced flux of glucose through the polyol pathway. As such, they can never be more effective than normoglycaemia, and so their potential benefits and limitations should be considered relative to the effects of prolonged euglycaemia. The clinical effects of ARIs can be put into perspective by assessing the effects of improved glycaemic control attained in randomised trials of intensive insulin treatment [such as the Diabetes Control and Complications Trial (DCCT)] and after pancreatic transplantation. Although direct comparison of these 3 interventions is hampered by differences in patient populations, duration and methods of follow-up and in the potency of ARIs, the effects of these 3 metabolic interventions and their course in time appear remarkably similar. For neuropathy, all 3 interventions induce an increase in average motor nerve conduction velocity of approximately 1 m/sec during the first months of treatment. At the same time, improvement of painful symptoms may occur. These changes probably largely represent a metabolic amelioration of the condition of the nerves. Around the second year of treatment with all 3 forms of metabolic improvement, an acceleration of nerve conduction of a similar magnitude occurs, with signs of structural nerve regeneration and some sensory recuperation. Experience with ARIs in nephropathy is still limited, but similar improvements in glomerular filtration rate and, less consistently, in urinary albumin excretion were found during short term normoglycaemia produced by all 3 forms of treatment. Comparison of a small number of studies, however, shows differences between intensive insulin regimens, pancreatic transplantation and ARIs in effects on retinopathy. Retinopathy often temporarily deteriorates in the early phases of improved glycaemic control, but this is not noted with ARIs. New microaneurysm formation was slightly reduced in a single long term study with the ARI sorbinil, but the preventive effects on the overall levels of retinopathy seemed less strong than in normoglycaemia trials of similar duration. However, the pharmacodynamic effects on inhibiting the polyol pathway differ among ARIs, and the half-life of the inhibiting effect of sorbinil may have been too short for a complete reduction of polyol pathway activity. The trials of prolonged intensive insulin therapy and pancreatic transplantation have demonstrated that very strict metabolic control must be maintained continuously for many years before a significant reduction of complications can be demonstrated.(ABSTRACT TRUNCATED AT 400 WORDS)

Diabetes mellitus but not impaired glucose tolerance is associated with dysfunction in peripheral nerves

To clarify whether long-term impaired glucose tolerance (IGT) is associated with dysfunction of peripheral and autonomic nerves, age-matched men with IGT and diabetes mellitus were followed prospectively for 12-15 years, when peripheral and autonomic nerve function was assessed. The patients comprised four subgroups: (1) 51 IGT subjects (duration of IGT at least 12-15 years); (2) 35 diabetic patients, with IGT 12-15 years ago, who later developed diabetes; (3) 34 diabetic patients, duration of diabetes at least 12-15 years; and (4) 62 age-matched non-diabetic control subjects. Mean age of the whole study population was 61 +/- 2 years (mean +/- SD), not different in the four groups. Peripheral nerve function tests included nerve conduction velocities, amplitudes, distal latencies, F-reflexes, and sensory perception thresholds for heat, cold, and vibration. Autonomic nerve function tests included the heart rate reaction during deep breathing (expiration to inspiration ratio) and to tilt (acceleration and brake indices). Despite 12-15 years of IGT, peripheral nerve function did not differ between IGT and control subjects, whereas autonomic nerve function deviated; an abnormal expiration to inspiration ratio (a sign of vagal nerve dysfunction) was significantly more common (15/51 versus 5/62; p < 0.01) in IGT than in control subjects. Diabetic patients (groups 2 and 3) showed lower conduction velocities (in general 2-4 m s-1 lower) than IGT and control subjects in all tested nerves. In conclusion, diabetes but not IGT, is associated with peripheral nerve dysfunction.