Diabetic neuropathies: a statement by the American Diabetes Association

Pathology and pathogenetic mechanisms of diabetic neuropathy: correlation with clinical signs and symptoms

Drastic increase in diabetic patients poses serious problems in the care of neuropathy so that there needs to explore the pathogenesis and to establish the effective treatment. Recent clinical and basic studies revealed characteristic pathophysiology of diabetic neuropathy and some clue to the direction of the treatment. The pathology of diabetic neuropathy is characterized by progressive nerve fiber loss that gives rise to positive and negative clinical signs and symptoms such as pain, paresthesia and loss of sensation. The nerve fiber loss takes the form of pan-modal pattern with proximo-distal gradient. Endoneurial microangiopathic change is also a constant feature of peripheral nerve pathology and negatively correlates with nerve fiber density. The vascular change and distal nerve fiber loss of small caliber, in particular, at the site of epidermis, commence even in subjects with impaired glucose tolerance and precede loss of nerve fibers in the nerve trunk of lower extremities. Pathogenetic mechanisms underlying the progressive nerve fiber loss seem to be multifactorial, including polyol pathway, glycation, reactive oxygen species, and altered protein kinase C activity. Clinical trials based on this background confirmed that fundamental treatment is in fact beneficial for the prevention and halting of this intractable disorder.

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.

The effect of alpha-lipoic acid on symptoms and skin blood flow in diabetic neuropathy

AIMS

Multiple pathogenic pathways are involved in diabetic neuropathy and diverse treatments have been tried without success. The aim of this study was to assess the effect of alpha-lipoic acid on skin blood flow in patients with diabetic neuropathy.

METHODS

We measured skin blood flow in 13 control subjects and 19 patients with diabetic neuropathy using the laser Doppler blood flow technique. Skin blood flow and the extent of skin blood flow changes were compared before and after diabetic patients received 600 mg/day alpha-lipoic acid intravenously for 14 days.

RESULTS

Although no significant differences in absolute values of skin blood flow or in the extent of changes were noted, symptoms were reduced after alpha-lipoic acid treatment.

CONCLUSIONS

This study suggests that alpha-lipoic acid, a potent antioxidant, improves symptoms of diabetic neuropathy. Larger studies are needed to determine whether improvements in skin blood flow also occur in patients with diabetic neuropathy.

Diabetes mellitus and the peripheral nervous system: manifestations and mechanisms

Diabetes targets the peripheral nervous system with several different patterns of damage and several mechanisms of disease. Diabetic polyneuropathy (DPN) is a common disorder involving a large proportion of diabetic patients, yet its pathophysiology is controversial. Mechanisms considered have included polyol flux, microangiopathy, oxidative stress, abnormal signaling from advanced glycation endproducts and growth factor deficiency. Although some clinical trials have demonstrated modest benefits in disease stabilization or pain therapy in DPN, robust therapy capable of reversing the disease is unavailable. In this review, general aspects of DPN and other diabetic neuropathies are examined, including a summary of recent therapeutic trials. A particular emphasis is placed on the evidence that the neurobiology of DPN reflects a unique yet common and disabling neurodegenerative disorder.

Mouse models of diabetic neuropathy

Diabetic neuropathy (DN) is a debilitating complication of type 1 and type 2 diabetes. Rodent models of DN do not fully replicate the pathology observed in human patients. We examined DN in streptozotocin (STZ)-induced [B6] and spontaneous type 1 diabetes [B6Ins2(Akita)] and spontaneous type 2 diabetes [B6-db/db, BKS-db/db]. Despite persistent hyperglycemia, the STZ-treated B6 and B6Ins2(Akita) mice were resistant to the development of DN. In contrast, DN developed in both type 2 diabetes models: the B6-db/db and BKS-db/db mice. The persistence of hyperglycemia and development of DN in the B6-db/db mice required an increased fat diet while the BKS-db/db mice developed severe DN and remained hyperglycemic on standard mouse chow. Our data support the hypothesis that genetic background and diet influence the development of DN and should be considered when developing new models of DN.

Diabetic neuropathies: clinical manifestations and current treatment options

Diabetic neuropathies are a heterogeneous group of disorders that include a wide range of abnormalities. They can be focal or diffuse, proximal or distal, affecting both peripheral and autonomic nervous systems, causing morbidity with significant impact on the quality of life of the person with diabetes, and can result in early death. Distal symmetric polyneuropathy, the most common form of diabetic neuropathy, usually involves small and large nerve fibers. Small-nerve-fiber neuropathy often presents with pain but without objective signs or electrophysiologic evidence of nerve damage, and is recognized as a component of the impaired glucose tolerance and metabolic syndromes. The greatest risk resulting from small-fiber neuropathy is foot ulceration and subsequent gangrene and amputation. Large-nerve-fiber neuropathies produce numbness, ataxia and uncoordination, impairing activities of daily living and causing falls and fractures. A careful history and detailed physical examination are essential for the diagnosis. Symptomatic therapy has become available and newer and better treatment modalities, based on etiologic factors, are being explored with potential for significant impact on morbidity and mortality. Preventive strategies and patient education still remain key factors in reducing complication rates and mortality.

Duloxetine for the Management of Diabetic Peripheral Neuropathic Pain: Evaluation of Functional Outcomes

OBJECTIVE

To assess the effectiveness of duloxetine, compared with placebo, on patient-reported health outcomes over a 12-week period, in the management of diabetic peripheral neuropathic pain (DPNP).

METHODS

The results were pooled from three 12-week multicenter, double-blind studies. In study 1 (N = 457), patients with DPNP were randomly assigned to treatment with duloxetine 20 mg once daily (QD), 60 mg QD, 60 mg twice daily (BID), or placebo. In studies 2 (N = 334) and 3 (N = 348), patients with DPNP were randomly assigned to treatment with duloxetine 60 mg QD, 60 mg BID, or placebo. Patient-reported functional outcomes were measured by the Short Form 36 (SF-36), the interference portion of the Brief Pain Inventory (BPI), and EuroQol 5D Health Questionnaire (EQ-5D). Results for all functional outcomes from the intent-to-treat and completer populations are discussed.

RESULTS

In the SF-36 health survey and the BPI interference, duloxetine 60 mg QD and 60 mg BID were significantly superior to placebo in all the domains (P <or= 0.03). In the analysis of the EQ-5D, duloxetine 60 mg QD (P = 0.004) and 60 mg BID (P < 0.001) were significantly better than placebo on all items.

CONCLUSIONS

Acute treatment with duloxetine was associated with significant improvement in functional outcomes in persons with DPNP.

Diabetic neuropathy: medical and surgical approaches

This article establishes the most critical, practical, and successful treatment options and their controversies for the practicing clinician caring for the patient with symptomatic diabetic neuropathy from the available literature.

Negative pressure wound therapy via vacuum-assisted closure following partial foot amputation: what is the role of wound chronicity?

Randomised clinical trials (RCTs) to evaluate diabetic foot wound therapies have systematically eliminated large acute wounds from evaluation, focusing only on smaller chronic wounds. The purpose of this study was to evaluate the proportion and rate of wound healing in acute and chronic wounds after partial foot amputation in individuals with diabetes treated with negative pressure wound therapy (NPWT) delivered by the vacuum-assisted closure (VAC) device or with standard wound therapy (SWT). This study constitutes a secondary analysis of patients enrolled in a 16-week RCT of NPWT: 162 open foot amputation wounds (mean wound size = 20.7 cm(2)) were included. Acute wounds were defined as the wounds less than 30 days after amputation, whereas chronic wounds as the wounds greater than 30 days. Inclusion criteria consisted of individuals older than 18 years, presence of a diabetic foot amputation wound up to the transmetatarsal level and adequate perfusion. Wound size and healing were confirmed by independent, blinded wound evaluators. Analyses were done on an intent-to-treat basis. There was a significantly higher proportion of acute wounds (SWT = 59; NPWT = 63) than chronic wounds (SWT = 26; NPWT = 14), evaluated in this clinical trial (P = 0.001). There was no significant difference in the proportion of acute and chronic wounds achieving complete wound closure in either treatment group. Despite this finding, the Kaplan-Meier curves demonstrated statistically significantly faster healing in the NPWT group in both acute (P = 0.030) and chronic wounds (P = 0.033). Among the patients treated with NPWT via the VAC, there was not a significant difference in healing as a function of chronicity. In both the acute and the chronic wound groups, results for patients treated with NPWT were superior to those for the patients treated with SWT. These results appear to indicate that wound duration should not deter the clinician from using this modality to treat complex wounds.

Differential hypertrophy and atrophy among all types of cutaneous innervation in the glabrous skin of the monkey hand during aging and naturally occurring type 2 diabetes

Diabetic neuropathy (DN) is a common severe complication of type 2 diabetes. The symptoms of chronic pain, tingling, and numbness are generally attributed to small fiber dysfunction. However, little is known about the pathology among innervation to distal extremities, where symptoms start earliest and are most severe, and where the innervation density is the highest and includes a wide variety of large fiber sensory endings. Our study assessed the immunochemistry, morphology, and density of the nonvascular innervation in glabrous skin from the hands of aged nondiabetic rhesus monkeys and from age-matched monkeys that had different durations of spontaneously occurring type 2 diabetes. Age-related reductions occurred among all types of innervation, with epidermal C-fiber endings preferentially diminishing earlier than presumptive Adelta-fiber endings. In diabetic monkeys epidermal innervation density diminished faster, became more unevenly distributed, and lost immunodetectable expression of calcitonin gene-related peptide and capsaicin receptors, TrpV1. Pacinian corpuscles also deteriorated. However, during the first few years of hyperglycemia, a surprising hypertrophy occurred among terminal arbors of remaining epidermal endings. Hypertrophy also occurred among Meissner corpuscles and Merkel endings supplied by Abeta fibers. After longer-term hyperglycemia, Meissner corpuscle hypertrophy declined but the number of corpuscles remained higher than in age-matched nondiabetics. However, the diabetic Meissner corpuscles had an abnormal structure and immunochemistry. In contrast, the expanded Merkel innervation was reduced to age-matched nondiabetic levels. These results indicate that transient phases of substantial innervation remodeling occur during the progression of diabetes, with differential increases and decreases occurring among the varieties of innervation.

Therapieoptionen der schmerzhaften diabetischen Polyneuropathie

Distal symmetrical polyneuropathy is the most frequent manifestation of diabetic neuropathy and crucially contributes to the development of diabetic foot and subsequent amputation in 70 to 80% of all cases. In 10 to 15% of affected patients considerable pain is present, in particular in early diabetic polyneuropathy. This review summarizes evidence based data on prevention, neuroregenerative, and symptomatic treatment of painful diabetic polyneuropathy. The most important clinical trials on treatment and prevention are presented. Conclusions from these clinical studies in particular detailed treatment recommendations including dosage and side effects are given. Combined treatments and escalating therapies for severe pain syndromes are discussed.

A 6-month, randomized, double-masked, placebo-controlled study evaluating the effects of the protein kinase C-beta inhibitor ruboxistaurin on skin microvascular blood flow and other measures of diabetic peripheral neuropathy

OBJECTIVE

Diabetes leads to protein kinase C (PKC)-beta overactivation and microvascular dysfunction, possibly resulting in disordered skin microvascular blood flow (SkBF) and other changes observed in diabetic peripheral neuropathy (DPN) patients. We investigate the effects of the isoform-selective PKC-beta inhibitor ruboxistaurin mesylate on neurovascular function and other measures of DPN.

RESEARCH DESIGN AND METHODS

Endothelium-dependent and C fiber-mediated SkBF, sensory symptoms, neurological deficits, nerve fiber morphometry, quantitative sensory and autonomic function testing, nerve conduction studies, quality of life (using the Norfolk Quality-of-Life Questionnaire for Diabetic Neuropathy [QOL-DN]), and adverse events were evaluated for 20 placebo- and 20 ruboxistaurin-treated (32 mg/day) DPN patients (aged > or =18 years; with type 1 or type 2 diabetes and A1C < or =11%) during a randomized, double-masked, single-site, 6-month study.

RESULTS

Endothelium-dependent (+78.2%, P < 0.03) and C fiber-mediated (+56.4%, P < 0.03) SkBF at the distal calf increased from baseline to end point. Significant improvements from baseline within the ruboxistaurin group were also observed for the Neuropathy Total Symptom Score-6 (NTSS-6) (3 months -48.3%, P = 0.01; end point -66.0%, P < 0.0006) and the Norfolk QOL-DN symptom subscore and total score (end point -41.2%, P = 0.01, and -41.0, P = 0.04, respectively). Between-group differences in baseline-to-end point change were observed for NTSS-6 total score (placebo -13.1%; ruboxistaurin -66.0%, P < 0.03) and the Norfolk QOL-DN symptom subscore (placebo -4.0%; ruboxistaurin -41.2%, P = 0.041). No significant ruboxistaurin effects were demonstrated for the remaining efficacy measures. Adverse events were consistent with those observed in previous ruboxistaurin studies.

CONCLUSIONS

In this cohort of DPN patients, ruboxistaurin enhanced SkBF at the distal calf, reduced sensory symptoms (NTSS-6), improved measures of Norfolk QOL-DN, and was well tolerated.

Type 2 diabetes and the risk of Parkinson's disease

OBJECTIVE

To evaluate whether type 2 diabetes at baseline is a risk factor for Parkinson's disease.

RESEARCH DESIGN AND METHODS

We prospectively followed 51,552 Finnish men and women 25-74 years of age without a history of Parkinson's disease at baseline. History of diabetes and other study parameters were determined at baseline using standardized measurements. Ascertainment of the Parkinson's disease status was based on the nationwide Social Insurance Institution's drug register data. Hazard ratios of incident Parkinson's disease associated with the history of type 2 diabetes were estimated.

RESULTS

During a mean follow-up period of 18.0 years, 324 men and 309 women developed incident Parkinson's disease. Age- and study year-adjusted hazard ratios of incident Parkinson's disease among subjects with type 2 diabetes, compared with those without it, were 1.80 (95% CI 1.03-3.15) in men, 1.93 (1.05-3.53) in women, and 1.85 (1.23-2.80) in men and women combined (adjusted also for sex). Further adjustment for BMI, systolic blood pressure, total cholesterol, education, leisure-time physical activity, smoking, alcohol drinking, and coffee and tea consumption affected the results only slightly. The multivariate adjusted association between type 2 diabetes and the risk of Parkinson's disease was also confirmed in stratified subgroup analysis.

CONCLUSIONS

These data suggest that type 2 diabetes is associated with an increased risk of Parkinson's disease. Surveillance bias might account for higher rates in diabetes. The mechanism behind this association between diabetes and Parkinson's disease is not known.

Randomized double-blind study comparing the efficacy and safety of lamotrigine and amitriptyline in painful diabetic neuropathy

AIMS

To compare the efficacy and safety of lamotrigine and amitriptyline in controlling chronic painful peripheral neuropathy in diabetic patients.

METHODS

A randomized, double-blind, crossover, active-control, clinical trial with variable dose titration was carried out (n = 53). Amitriptyline orally, at doses of 10, 25 and 50 mg at night-time, each dose for 2 weeks, and lamotrigine orally, at doses of 25, 50 and 100 mg twice daily, each dose for 2 weeks, by optional titration were used. There was a placebo washout period for 2 weeks between the two drugs. Assessment for pain relief, overall improvement and adverse events were carried out.

RESULTS

Good, moderate and mild pain relief were noted in 19 (41%), six (13%) and seven (15%) patients on lamotrigine and 13 (28%), five (11%) and 15 (33%) patients on amitriptyline, respectively, by patient's global assessment of efficacy and safety. Patient and physicians global assessment, McGill pain questionnaire and Likert pain scale showed no significant difference between the treatments, although improvement with both treatments was seen from 2 weeks. Of the 44 adverse events reported, 33 (75%) were with amitriptyline, sedation being the commonest [in 19 (43%) patients]. Lamotrigine caused adverse events in 11 (25%), of which rash in three (7%) and elevations of creatinine in four (9%) were the most common. The preferred lamotrigine dose was 25 mg twice daily.

CONCLUSIONS

As there are few differences between the two treatments in efficacy, lamotrigine 25 mg twice daily might be the first choice as it is associated with fewer adverse effects in our population.

Diabetic neuropathy: classification, measurement and treatment

PURPOSE OF REVIEW

Diabetic neuropathies comprise a number of conditions affecting somatic or autonomic nerves and are the most common of the long-term diabetic complications. This review considers recent developments in the classification and noninvasive assessment of somatic neuropathy, and describes new approaches to the management of painful neuropathic symptoms.

RECENT FINDINGS

Classification of the diabetic neuropathies needs modifying to include the recently described 'prediabetic neuropathy' or 'neuropathy of impaired glucose tolerance'. There is increasing evidence to support the use of minimally invasive skin biopsies for evaluating small fibre neuropathies, and more recently, the noninvasive corneal confocal microscopy, which enables direct visualization of peripheral nerve in vivo. For those with painful neuropathic symptoms, a number of evidence-based therapies are now available.

SUMMARY

Patients with 'idiopathic neuropathy' should be screened for evidence of impaired glucose tolerance and considered for lifestyle management. Future trials of potential therapies will benefit from more relevant surrogate endpoints. Those with painful neuropathy should only be prescribed therapies whose efficacy has been confirmed by independent randomized controlled trials.

Treatment of diabetic polyneuropathy: Update 2006

At least one of four diabetic patients is affected by distal symmetric polyneuropathy (DSP), which represents a major health problem, as it may present with partly excruciating neuropathic pain and is responsible for substantial morbidity, increased mortality, and impaired quality of life. Treatment is based on four cornerstones: (a) causal treatment aimed at (near)-normoglycemia, (b) treatment based on pathogenetic mechanisms, (c) symptomatic treatment, and (d) avoidance of risk factors and complications. Recent experimental studies suggest a multifactorial pathogenesis of diabetic neuropathy. From the clinical point of view it is important to note that, on the basis of these pathogenetic mechanisms, therapeutic approaches could be derived, some of which are currently being evaluated in clinical trials. Among these agents only alpha-lipoic acid is available for treatment in several countries and epalrestat in Japan. Although several novel analgesic drugs, such as duloxetine and pregabalin, have recently been introduced into clinical practice, the pharmacological treatment of chronic painful diabetic neuropathy remains a challenge for the physician. Individual tolerability remains a major aspect in any treatment decision. Epidemiological data indicate that not only increased alcohol consumption but also the traditional cardiovascular risk factors, such as hypertension, smoking, and visceral obesity, play a role in development and progression of diabetic neuropathy and, hence, need to be prevented or treated.

Impaired skin microvascular reactivity in painful diabetic neuropathy

OBJECTIVE

The pathogenesis of painful diabetic neuropathy (PDN) is not clear. Following our in vivo observations of increased sural nerve epineurial blood flow in patients with PDN, we investigated the cutaneous microcirculation of the foot by laser Doppler flowmetry to determine if the epineurial findings were just confined to the nerve or more widespread in other vascular beds.

RESEARCH DESIGN AND METHODS

We measured foot skin vasodilator responses to acetylcholine (Ach) and sodium nitroprusside (SNP) and vasoconstrictor responses to sympathetic (deepest possible gasp) stimulation in 5 healthy control subjects, 10 non-neuropathic diabetic (NND) patients, 10 diabetic patients with painless neuropathy (PLDN), and 8 diabetic patients with PDN.

RESULTS

In PDN, there were significantly reduced responses to Ach (ANOVA P = 0.003) and vasoconstrictor inspiratory gasp (ANOVA P < 0.001) but not to SNP (NS). Post hoc analysis showed significant differences in Ach-induced vasodilation between PDN and nondiabetic control subjects (P < 0.05) as well as between PDN and NND (P < 0.05) but not PDN and PLDN (NS). There were no significant differences for SNP-induced vasodilation. However, there were significant differences in the vasoconstrictor response between PDN and control, NND, and PLDN (P < 0.01).

CONCLUSIONS

We found an impairment of cutaneous endothelium-related vasodilation and C-fiber-mediated vasoconstriction in PDN. Inappropriate local blood flow regulation may have a role in the pathogenesis of pain in diabetic neuropathy. Prospective studies are required to determine the temporal relationship of these changes in relation to the emergence of neuropathic pain.

Isolated Use of Vibration Perception Thresholds and Semmes-Weinstein Monofilament in Diagnosing Diabetic Polyneuropathy: “The North Catalonia Diabetes Study”

Several systems are used for the diagnosis of diabeticpolyneuropathy (DPN). We analyzed the isolated use of vibration perception thresholds (VPTs) or monofilament (MF) for the diagnosis of DPN. A group of 400 patients who had type 2 diabetes was selected from the North Catalonia Study Group. A clinical neurologic evaluation was performed based on three categories of the San Antonio Consensus. Neurothesiometer and quantitative tuning fork explored VPT, and MF was assessed by Olmos and Michigan Diabetic Neuropathy Score (MDNS) criteria. The use of VPT and MF showed a high specificity and low sensitivity. MF, by MDNS criteria, was more sensitive and specific, and showed more accurate positive and negative predictive values. The predicted probability of DPN diagnosis was higher with a tuning fork evaluation.

Disfunção autonômica cardiovascular no diabetes mellitus experimental

Muitas informações novas têm sido publicadas nos últimos anos a respeito da fisiopatologia da disfunção autonômica cardiovascular em ratos e camundongos diabéticos. Nosso grupo tem estudado o curso temporal das alterações cardiovasculares associadas ao diabetes experimental há alguns anos, obtendo evidências consistentes de grave disautonomia em modelos animais de diabetes. O objetivo deste trabalho foi revisar a contribuição que estudos envolvendo diferentes modelos de deficiência e resistência à insulina têm fornecido para o entendimento, tratamento e prevenção da disfunção autonômica cardiovascular do diabetes.

Sexual dysfunction in men and women with endocrine disorders

Endocrine disease frequently interrupts sexual function, and sexual dysfunction may signal serious endocrine disease. Diabetic autonomic neuropathy and endothelial dysfunction impair erectile function, and phosphodiesterase inhibition produces only moderate benefit. The effect of diabetes on women's sexual function is complex: the most consistent finding is a correlation between sexual dysfunction and depression. Reductions in testosterone level in men are associated with low sexual desire and reduced nocturnal erections and ejaculate volume, all of which improve with testosterone supplementation. The age-dependent decline in testosterone production in men is not associated with precise sexual symptoms, and supplementation has not been shown to produce sexual benefit. In women, sexual dysfunction has not been associated with serum testosterone, but this may be confounded by limitations of assays at low concentrations and by the greater importance of intracellular production of testosterone in women than in men. Testosterone supplementation after menopause does improve some aspects of sexual function in women, but long-term outcome data are needed. More research on the sexual effects of abnormal adrenal and thyroid function, hyperprolactinaemia, and metabolic syndrome should also be prioritised. We have good data on local management of the genital consequences of oestrogen lack, but need to better understand the potential role of systemic oestrogen supplementation from menopause onwards in sexually symptomatic women.

Early diabetic neuropathy: Triggers and mechanisms

Peripheral neuropathy, and specifically distal peripheral neuropathy (DPN), is one of the most frequent and troublesome complications of diabetes mellitus. It is the major reason for morbidity and mortality among diabetic patients. It is also frequently associated with debilitating pain. Unfortunately, our knowledge of the natural history and pathogenesis of this disease remains limited. For a long time hyperglycemia was viewed as a major, if not the sole factor, responsible for all symptomatic presentations of DPN. Multiple clinical observations and animal studies supported this view. The control of blood glucose as an obligatory step of therapy to delay or reverse DPN is no longer an arguable issue. However, while supporting evidence for the glycemic hypothesis has accumulated, multiple controversies accumulated as well. It is obvious now that DPN cannot be fully understood without considering factors besides hyperglycemia. Some symptoms of DPN may develop with little, if any, correlation with the glycemic status of a patient. It is also clear that identification of these putative non-glycemic mechanisms of DPN is of utmost importance for our understanding of failures with existing treatments and for the development of new approaches for diagnosis and therapy of DPN. In this work we will review the strengths and weaknesses of the glycemic hypothesis, focusing on clinical and animal data and on the pathogenesis of early stages and triggers of DPN other than hyperglycemia.

Hypomagnesemia in patients with type 2 diabetes

Hypomagnesemia has been reported to occur at an increased frequency among patients with type 2 diabetes compared with their counterparts without diabetes. Despite numerous reports linking hypomagnesemia to chronic diabetic complications, attention to this issue is poor among clinicians. This article reviews the literature on the metabolism of magnesium, incidence of hypomagnesemia in patients with type 2 diabetes, implicated contributing factors, and associated complications. Hypomagnesemia occurs at an incidence of 13.5 to 47.7% among patients with type 2 diabetes. Poor dietary intake, autonomic dysfunction, altered insulin metabolism, glomerular hyperfiltration, osmotic diuresis, recurrent metabolic acidosis, hypophosphatemia, and hypokalemia may be contributory. Hypomagnesemia has been linked to poor glycemic control, coronary artery diseases, hypertension, diabetic retinopathy, nephropathy, neuropathy, and foot ulcerations. The increased incidence of hypomagnesemia among patients with type 2 diabetes presumably is multifactorial. Because current data suggest adverse outcomes in association with hypomagnesemia, it is prudent to monitor magnesium routinely in this patient population and treat the condition whenever possible.

Cardiovascular and cerebrovascular responses to lower body negative pressure in type 2 diabetic patients

In diabetic patients, vascular disease and autonomic dysfunction might compromise cerebral autoregulation and contribute to orthostatic intolerance. The aim of our study was to determine whether impaired cerebral autoregulation contributes to orthostatic intolerance during lower body negative pressure in diabetic patients. Thirteen patients with early-stage type 2 diabetes were studied. We continuously recorded RR-interval, mean blood pressure and mean middle cerebral artery blood flow velocity at rest and during lower body negative pressure applied at -20 and -40 mm Hg. Spectral powers of RR-interval, blood pressure and cerebral blood flow velocity were analyzed in the sympathetically mediated low (LF: 0.04-0.15 Hz) and the high (HF: 0.15-0.5 Hz) frequency ranges. Cerebral autoregulation was assessed from the transfer function gain and phase shift between LF oscillations of blood pressure and cerebral blood flow velocity. In the diabetic patients, lower body negative pressure decreased the RR-interval, i.e. increased heart rate, while blood pressure and cerebral blood flow velocity decreased. Transfer function gain and phase shift remained stable. Lower body negative pressure did not induce the normal increase in sympathetically mediated LF-powers of blood pressure and cerebral blood flow velocity in our patients indicating sympathetic dysfunction. The stable phase shift, however, suggests intact cerebral autoregulation. The dying back pathology in diabetic neuropathy may explain an earlier and greater impairment of peripheral vasomotor than cerebrovascular control, thus maintaining cerebral blood flow constant and protecting patients from symptoms of presyncope.

Clinical Manifestations and Current Treatment options for Diabetic Neuropathies

OBJECTIVE

To review the clinical manifestations and current treatment options for diabetic neuropathies, one of the most common complications of diabetes mellitus.

METHODS

We performed a MEDLINE search of the English-language literature using a combination of words (diabetic neuropathy, diabetic autonomic neuropathy, diagnosis and treatment) to identify original studies, consensus statements, and reviews on diabetic neuropathies published in the past 25 years. Emphasis was placed on clinical manifestations of distal polyneuropathy and its treatment, especially new therapies.

RESULTS

Distal symmetric polyneuropathy, the most common form of diabetic neuropathy, usually involves small and large nerve fibers. Small-nerve fiber neuropathy often presents with pain and loss of intraepidermal nerve fibers, but without objective signs or electrophysiologic evidence of nerve damage. This type of neuropathy is a component of impaired glucose tolerance and the metabolic syndrome. The greatest risk from small-fiber neuropathy is foot ulceration and subsequent gangrene and amputation. Large-nerve fiber neuropathy produces numbness, ataxia, and incoordination, thus impairing activities of daily living and causing falls and fractures. Successfully treating diabetic neuropathy requires addressing the underlying pathogenic mechanisms, treating symptoms to improve quality of life, and preventing progression and complications of diabetes mellitus. Two new drugs, duloxetine hydrochloride and pregabalin, have recently been approved for treatment of neuropathic pain associated with diabetes mellitus.

CONCLUSION

Symptomatic therapy has become available and newer and better treatment modalities, based on etiologic factors, are being explored with potential for clinically significant reduction of morbidity and mortality. Preventive strategies and patient and physician education still remain key factors in reducing complication rates and mortality.

Does treatment with duloxetine for neuropathic pain impact glycemic control?

OBJECTIVE

We examined changes in metabolic parameters in clinical trials of duloxetine for diabetic peripheral neuropathic pain (DPNP).

RESEARCH DESIGN AND METHODS

Data were pooled from three similarly designed clinical trials. Adults with diabetes and DPNP (n = 1,024) were randomized to 60 mg duloxetine q.d., 60 mg b.i.d., or placebo for 12 weeks. Subjects (n = 867) were re-randomized to 60 mg duloxetine b.i.d. or routine care for an additional 52 weeks. Mean changes in plasma glucose, lipids, and weight were evaluated. Regression and subgroup analyses were used to identify relationships between metabolic measures and demographic, clinical, and electrophysiological parameters.

RESULTS

Duloxetine treatment resulted in modest increases in fasting plasma glucose in short- and long-term studies (0.50 and 0.67 mmol/l, respectively). A1C did not increase in placebo-controlled studies; however, a greater increase was seen relative to routine care in long-term studies (0.52 vs. 0.19%). Short-term duloxetine treatment resulted in mean weight loss (-1.03 kg; P < 0.001 vs. placebo), whereas slight, nonsignificant weight gain was seen in both duloxetine and routine care groups with longer treatment. Between-group differences were seen for some lipid parameters, but these changes were generally small. Metabolic changes did not appear to impact improvement in pain severity seen with duloxetine, and nerve conduction was also not significantly impacted by treatment.

CONCLUSIONS

Duloxetine treatment was associated with modest changes in glycemia in patients with DPNP. Other metabolic changes were limited and of uncertain significance. These changes did not impact the significant improvement in pain observed with duloxetine treatment.

C-Peptide replacement therapy and sensory nerve function in type 1 diabetic neuropathy

OBJECTIVE

C-peptide replacement in animals results in amelioration of diabetes-induced functional and structural abnormalities in peripheral nerves. The present study was undertaken to examine whether C-peptide administration to patients with type 1 diabetes and peripheral neuropathy improves sensory nerve function.

RESEARCH DESIGN AND METHODS

This was an exploratory, double-blinded, randomized, and placebo-controlled study with three study groups that was carried out at five centers in Sweden. C-peptide was given as a replacement dose (1.5 mg/day, divided into four subcutaneous doses) or a dose three times higher (4.5 mg/day) during 6 months. Neurological examination and neurophysiological measurements were performed before and after 6 months of treatment with C-peptide or placebo.

RESULTS

The age of the 139 patients who completed the protocol was 44.2 +/- 0.6 (mean +/- SE) years and their duration of diabetes was 30.6 +/- 0.8 years. Clinical neurological impairment (NIA) (score >7 points) of the lower extremities was present in 86% of the patients at baseline. Sensory nerve conduction velocity (SCV) was 2.6 +/- 0.08 SD below body height-corrected normal values at baseline and improved similarly within the two C-peptide groups (P < 0.007). The number of patients responding with a SCV peak potential improvement >1.0 m/s was greater in C-peptide-treated patients than in those receiving placebo (P < 0.03). In the least severely affected patients (SCV < 2.5 SD below normal at baseline, n = 70) SCV improved by 1.0 m/s (P < 0.014 vs. placebo). NIA score and vibration perception both improved within the C-peptide-treated groups (P < 0.011 and P < 0.002). A1C levels (7.6 +/- 0.1% at baseline) decreased slightly but similarly in C-peptide-and placebo-treated patients during the study.

CONCLUSIONS

C-peptide treatment for 6 months improves sensory nerve function in early-stage type 1 diabetic neuropathy.

Correlation of vibratory quantitative sensory testing and nerve conduction studies in patients with diabetes

Monitoring the course of diabetic peripheral neuropathy (DPN) remains a challenge. Besides clinical examination, nerve conduction studies (NCS) and quantitative sensory testing (QST) are the most commonly used methods for evaluating peripheral nerve function in clinical trials and population studies. In this study the correlation between vibratory QST and NCS was determined. Patients (N = 227) with diabetes mellitus participated in this multicenter, single-visit, cross-sectional study. QST of vibration measured with the CASE IV system was compared with a composite score of peroneal motor and tibial motor NCS and with individual attributes of peroneal, tibial, and sural nerves. The correlation between QST and composite score of NCS was 0.234 (Pearson correlation coefficient, P = 0.001). The correlations between QST and individual attributes of NCS ranged from 0.189 to 0.480 (Pearson correlation coefficients, P < 0.001). The low to moderate correlation between QST and NCS suggests that these tests cannot replace each other but are complementary.

Quantitative Assessment of Diabetic Peripheral Neuropathy with use of the Clanging Tuning Fork Test

OBJECTIVE

To describe the clanging tuning fork (CTF) test, a novel method for using the C 128-Hz tuning fork to test for diabetic peripheral neuropathy (DPN), to evaluate the accuracy and reproducibility of this technique, and to compare it with the 5.07 (10 g) Semmes-Weinstein monofilament test.

METHODS

To determine the mean and standard deviation for the CTF test, repeated measurements were taken on one toe of 12 patients with diabetes during one visit. After these tests, 30 randomly selected patients were tested on both feet, with right and left scores compared for reproducibility of the results. The scores of the CTF test were compared with the monofilament scores in 45 patients with diabetes. Presence of foot ulcers in 81 patients was correlated with both test scores.

RESULTS

The mean duration of vibration sensation was 10.2 seconds, with a standard deviation of +/-1.3 seconds. The Pearson correlation coefficient comparing the right and the left foot scores for the same patient was 0.947 (P<0.05). Among patients with 8 seconds or less of vibration perception, results of monofilament testing were abnormal only in those whose vibration perception was less than or equal to 4 seconds. Of 32 patients with vibration perception of 4 seconds or less, 50% had normal monofilament test scores, including 29% of 17 patients with absent vibratory sensation.

CONCLUSION

The CTF test is reproducible and accurate. It provides a quantitative assessment of DPN and can document severe neuropathy, even in the presence of a normal result with the 10-g monofilament test. The risk of foot ulcers, which is associated with diminished vibratory sensation, can therefore be detected earlier and more accurately with the CTF test. The CTF test should replace the 10-g monofilament test as the recommended technique for detection of DPN.

Diabetes mellitus and cardiovascular disease

Cardiovascular diseases include hypertension, coronary heart disease, acute myocardial infarction, heart failure, sudden death, peripheral vascular disease, and stroke. The high risk of cardiovascular disease in individuals with diabetes was recognized more than 30 years ago. Appreciation of the multiple risk factors and complex pathophysiologic process responsible for cardiovascular disease in individuals with both type 1 and 2 diabetes is critical for the prevention, early detection, and management of cardiovascular disease in this population. The focus of this article is on the acute and chronic manifestations of coronary heart disease.

Diabetic nerve conduction abnormalities in the primary care setting

BACKGROUND

Nerve conduction studies (NCS) are the most objective measure of nerve function, and their use is recommended in the clinical and epidemiological evaluation of diabetic polyneuropathy (DPN). The purpose of this study was to utilize automated NCS technology to characterize nerve conduction of patients with diabetes in primary care settings.

METHODS

The Diabetes cohort was drawn from 28 community clinics. The Control cohort consisted of subjects without diabetes and without evidence of neuropathy. Bilateral peroneal NCS were performed with an automated NCS instrument (NC-stat, NeuroMetrix, Inc., Waltham, MA). Neuropathic symptoms were quantified using an abbreviated form of the NTSS-6 questionnaire. Risk factors for abnormal NCS were determined using multivariate regression modeling.

RESULTS

Data were collected for 172 control subjects and 1,358 subjects with diabetes. Statistically significant differences in peroneal NCS were found. Of the Diabetes cohort, 75.1% had at least one NCS abnormality, and 53.2% had bilateral abnormalities. Of the asymptomatic patients, 45% had bilateral NCS abnormalities. By contrast, 40% of those with clinically significant symptoms lacked bilateral NCS abnormalities. Independent predictors for bilateral NCS abnormalities were age, height, weight, hemoglobin A1c (HbA1c), and duration of diabetes. Up to 16% of the variance in NCS measurements was explained by HbA1c, duration of diabetes, and several demographic variables.

CONCLUSIONS

This study suggests that automated NCS can provide nerve conduction confirmation of DPN in primary care settings and has clinical utility. These findings have important implications for the clinical and epidemiological evaluation of DPN.

Efeitos fisiológicos do treinamento físico em pacientes portadores de diabetes tipo 1

Insulinoterapia, atividade física regular e planejamento alimentar, em conjunto, consistem na abordagem mais completa no tratamento de portadores de diabetes mellitus tipo 1 (DM1). Estudos clínicos e experimentais têm evidenciado os benefícios do treinamento físico em indivíduos com DM1, tais como melhora na sensibilidade à insulina, redução das doses de insulina e atenuação das disfunções autonômicas e cardiovasculares. Essa revisão aborda as adaptações fisiológicas ao treinamento físico no indivíduo com DM1 e discute as recomendações e prescrição de atividade física para esta população.

Oral treatment with alpha-lipoic acid improves symptomatic diabetic polyneuropathy: the SYDNEY 2 trial

OBJECTIVE

The aim of this trial was to evaluate the effects of alpha-lipoic acid (ALA) on positive sensory symptoms and neuropathic deficits in diabetic patients with distal symmetric polyneuropathy (DSP).

RESEARCH DESIGN AND METHODS

In this multicenter, randomized, double-blind, placebo-controlled trial, 181 diabetic patients in Russia and Israel received once-daily oral doses of 600 mg (n = 45) (ALA600), 1,200 mg (n = 47) (ALA1200), and 1,800 mg (ALA1800) of ALA (n = 46) or placebo (n = 43) for 5 weeks after a 1-week placebo run-in period. The primary outcome measure was the change from baseline of the Total Symptom Score (TSS), including stabbing pain, burning pain, paresthesia, and asleep numbness of the feet. Secondary end points included individual symptoms of TSS, Neuropathy Symptoms and Change (NSC) score, Neuropathy Impairment Score (NIS), and patients' global assessment of efficacy.

RESULTS

Mean TSS did not differ significantly at baseline among the treatment groups and on average decreased by 4.9 points (51%) in ALA600, 4.5 (48%) in ALA1200, and 4.7 (52%) in ALA1800 compared with 2.9 points (32%) in the placebo group (all P < 0.05 vs. placebo). The corresponding response rates (>/=50% reduction in TSS) were 62, 50, 56, and 26%, respectively. Significant improvements favoring all three ALA groups were also noted for stabbing and burning pain, the NSC score, and the patients' global assessment of efficacy. The NIS was numerically reduced. Safety analysis showed a dose-dependent increase in nausea, vomiting, and vertigo.

CONCLUSIONS

Oral treatment with ALA for 5 weeks improved neuropathic symptoms and deficits in patients with DSP. An oral dose of 600 mg once daily appears to provide the optimum risk-to-benefit ratio.

Duloxetine in the treatment of diabetic peripheral neuropathic pain

Diabetic peripheral neuropathic pain is a common complication of diabetes mellitus that adversely affects the quality of life of these patients. Many antidepressants and anticonvulsants are effective in relieving diabetic peripheral neuropathic pain. Duloxetine, a dual serotonin and norepinephrine reuptake inhibitor, was very effective in reducing diabetic peripheral neuropathic pain and improving quality of life and was the first antidepressant approved by regulatory authorities for the treatment of diabetic peripheral neuropathic pain. Safety was evaluated in 1074 diabetic peripheral neuropathic pain patients representing 472 patient-years exposure. More duloxetine-treated (79/568, 13.9%) than placebo-treated (16/223, 7.2%; p = 0.008) patients discontinued owing to adverse events. Duloxetine should be used with similar cautions to the newer antidepressants. In addition, rare duloxetine-induced hepatic enzyme elevations should result in discontinuation of duloxetine therapy. Duloxetine should prove effective in other painful conditions and might provide additional relief when used with anticonvulsants in neuropathic conditions.

Diabetic neuropathies: diagnosis and treatment

Diabetic neuropathy can affect every organ system of the body. Diagnosis of diabetic neuropathy is usually one of exclusion. Clinical guidelines and the introduction of new medications for pain relief in peripheral neuropathy are improving medical and nursing management. Simpler diagnostic tests for cardiac autonomic neuropathy, which can be performed in an office setting, may mean earlier recognition and treatment with less mortality. Oral medications for the treatment of erectile dysfunction make it easier for the patient to seek treatment for a condition that impact quality of life.

Recent clinical advances in diabetic polyneuropathy

PURPOSE OF REVIEW

Recent dramatic increases in the incidence and prevalence of diabetes make an understanding of chronic symmetric sensorimotor diabetic polyneuropathy, the most common and problematic of chronic diabetic complications, essential for a wide range of medical practitioners.

RECENT FINDINGS

The demonstration of neuropathic dysfunction in patients with prediabetes or impaired glucose tolerance emphasizes the susceptibility of peripheral nerve fibers, especially small A delta fibers and C fibers, to relatively mild, short-duration hyperglycemia. New testing can reveal peripheral nerve dysfunction prior to clinical neuropathic symptoms and signs. In the absence of effective medications to halt or reverse nerve damage or promote nerve regeneration, early diagnosis of diabetic polyneuropathy, followed by tight glycemic control with diet and exercise, offers the best opportunity to prevent progressive symptoms of sensory loss, pain, autonomic dysfunction, ulcerations, and amputations. Some patients with impaired glucose tolerance have a reversal of neuropathic features with tight glycemic control. Nonpharmacologic therapies for neuropathic pain in diabetic polyneuropathy appear promising.

SUMMARY

Tight glycemic control, especially early in diabetes, is the best approach to minimizing the prevalence and severity of diabetic polyneuropathy and makes research into the deleterious effects of even mild hyperglycemia imperative.

Validation of a novel point-of-care nerve conduction device for the detection of diabetic sensorimotor polyneuropathy

OBJECTIVE

The diagnosis of diabetic sensorimotor polyneuropathy using objective electrophysiological tests is hindered by limited access to the specialized laboratories and technicians that perform and interpret them. We evaluated the performance characteristics of a novel portable and automated point-of-care nerve conduction study device, which can be operated by nontechnical personnel, and compared it with conventional nerve conduction studies performed in a specialist setting.

RESEARCH DESIGN AND METHODS

Seventy-two consecutive patients with diabetes (8 type 1, 64 type 2) from a diabetes and a neuropathy outpatient clinic were evaluated concurrently with conventional nerve conduction studies (the reference standard) and the point-of-care device for sural nerve function (sural nerve amplitude potentials in microvolts [microV]).

RESULTS

Sural nerve amplitude potentials measured by the point-of-care device shared very strong correlation with the reference standard (Spearman's correlation coefficient 0.95, P < 0.001). The Bland and Altman method yielded agreement despite a small systematic underestimation by the point-of-care device of 1.2 +/- 3.4 microV. Despite this small systematic bias, the sensitivity and specificity of normal and abnormal sural nerve amplitude potentials measured by the point-of-care device for the detection of diabetic sensorimotor polyneuropathy defined by standard clinical and electrophysiological criteria were 92 and 82%, respectively.

CONCLUSIONS

A novel point-of-care device has excellent diagnostic accuracy for detecting electrophysiological abnormality in the sural nerve of patients who have diabetes. This automated device represents an alternative to conventional nerve conduction studies for the diagnosis of diabetic sensorimotor polyneuropathy.

Vibration perception threshold--a valuable assessment of neural dysfunction in people with diabetes

Diabetic peripheral neuropathy (DPN) has been identified as a key element in the causal pathway to foot ulceration and other lower-extremity complications, impaired quality of life and increased mortality. Early detection is essential to optimise effective risk management, including adequate foot care, patient education, and future pharmacological therapy. However, data suggest that screening has been mostly sub-optimal, and many physicians remain unfamiliar with non-invasive screening tests. There is evidence in the literature to suggest that vibration perception threshold (VPT) measures can be used to easily and accurately identify at-risk diabetic patients, including those with early neuropathic deficits. These measures have been used in population-based studies and are associated with an increased risk of severe and expensive outcomes, such as ulcers and amputations. Incorporating VPT testing into clinical practice has the potential to significantly improve the outcomes in patients with DPN, thereby substantially reducing the socio-economic burden of this common and challenging disease.

How to better systematize the diagnosis of neuropathy?

Two attitudes can be proposed, one consisting of making a diagnosis of neuropathy, the other seeking to grade the stage that it has reached in order to give a prognosis and above all determine the right way in which to educate the patient. In order to do this, it is important for the diagnosis to be thorough. It should be based both on listening to what the patient has to say and examining him/her. It is vital to listen to the patient because the warning signs are discreet, yet very evocative, and they will be a great help in making a positive diagnosis. They should not be confused with signs of arterial damage. They should then be interpreted by means of clinical examination and the tools that are available, i.e. essentially monitoring the osteo-tendinous reflexes and sensory signs. The sensory signs can only be studied with high-quality instruments, i.e. either a monofilament of proven technical quality and that should be used with care in line with good clinical practice recommendations, or by using a graduated tuning fork, or a neuroesthesiometer which will make it possible to obtained graduated responses, not simply binary responses of the "yes/no" variety. A whole series of scores have been put forward combining both functional and physical signs, making it possible to try to quantify the stage reached and the extent of the neuropathy. It is only by using a thorough and regularly applied routine that we can progress to establishing a better prognosis and providing a better educational service for the patient.

Oesophageal motility disorders in type 1 diabetes mellitus and their relation to cardiovascular autonomic neuropathy

The relationship between cardiovascular autonomic neuropathy (CVAN) and oesophageal dysfunction in diabetes mellitus has not been well established because reports are contradictory. The aim of this study was to assess oesophageal function and its correlation with CVAN in type 1 diabetic patients without oesophageal symptoms. Forty-six type 1 diabetic patients without oesophageal symptoms (DG) and 34 healthy volunteers (CG) were studied. Both groups underwent CVAN tests and oesophageal manometry and pH-metry. Differences between groups regarding results of cardiovascular autonomic tests and oesophageal studies were statistically analysed. Compared with the CG, the DG group showed insufficient lower oesophageal sphincter (LOS) relaxation and a higher percentage of simultaneous waves (P < 0.01). Patients with CVAN (n = 22) showed a higher prevalence of pathological simultaneous contractions (>10%), and the prevalence of simultaneous waves related to the degree of autonomic neuropathy was: 9% of patients without CVAN, 7% of those suspected to have it and 50% of patients with CVAN (P < 0.001). Factors associated with the presence of pathological simultaneous waves (>10%) were the presence of CVAN and duration of diabetes (P < 0.05, logistic regression analysis). Increase in simultaneous waves and impaired relaxation of LOS are more frequent in diabetic patients with CVAN.

Low blood flow estimates in lower-leg arteries predict cardiovascular events in Japanese patients with type 2 diabetes with normal ankle-brachial indexes

OBJECTIVE

To examine the association of baseline measures in lower-leg arteries and conventional cardiovascular risk factors with the incidence of cardiovascular disease (CVD) events in type 2 diabetic patients with normal ankle-brachial indexes (ABIs) (>0.9).

RESEARCH DESIGN AND METHODS

We studied 129 type 2 diabetic patients and 35 age-matched nondiabetic subjects with no apparent CVD consecutively admitted to our hospital. At baseline, total flow volume and resistive index, as an index of vascular resistance, at the popliteal artery was evaluated using gated two-dimensional cine-mode phase-contrast magnetic resonance imaging. Patients were followed 4.8 +/- 1.5 years (range 3.0-8.2) or until their first event of CVD.

RESULTS

On follow-up, 16 patients developed primary CVD events. Patients with CVD had lower blood flow (P < 0.01) and higher vascular resistance (P < 0.05) than patients without CVD. When the patients were grouped into tertiles according to their levels of total flow volume (129.6-85.5, 85.3-63.3, and 62.7-23.8 ml/min), Kaplan-Meier analysis showed a higher probability of developing CVD events in patients in the lowest than in patients in the highest (P = 0.0199, log-rank test) tertile. Multivariate Cox proportional hazards analysis revealed that the lowest tertile for flow volume (hazard ratio [HR] 8.60, 95% CI 1.61-45.97, P = 0.012), hypertension (3.99, 1.12-14.25, P = 0.033), and smoking status (12.01, 1.21-119.28, P = 0.034) were significant independent predictors of CVD events.

CONCLUSIONS

We have demonstrated that low blood flow estimates in lower-leg arteries may be predictive for CVD events among Japanese patients with type 2 diabetes even though they have a normal ABI.