OBJECTIVE -Because ␣-lipoic acid (ALA), a potent antioxidant, prevents or improves nerve conduction attributes, endoneurial blood flow, and nerve (Na(ϩ) K(ϩ) ATPase activity in experimental diabetes and in humans and may improve positive neuropathic sensory symptoms, in this report we further assess the safety and efficacy of ALA on the Total Symptom Score (TSS), a measure of positive neuropathic sensory symptoms.RESEARCH DESIGN AND METHODS -Metabolically stable diabetic patients with symptomatic (stage 2) diabetic sensorimotor polyneuropathy (DSPN) were randomized to a parallel, double-blind study of ALA (600 mg) (n ϭ 60) or placebo (n ϭ 60) infused daily intravenously for 5 days/week for 14 treatments. The primary end point was change of the sum score of daily assessments of severity and duration of TSS. Secondary end points were sum scores of neuropathy signs (NIS), symptoms (NSC), attributes of nerve conduction, quantitative sensation tests (QSTs), and an autonomic test.RESULTS -At randomization, the groups were not significantly different by the criteria of metabolic control or neuropathic end points. After 14 treatments, the TSS of the ALA group had improved from baseline by an average of 5.7 points and the placebo group by an average of 1.8 points (P Ͻ 0.001). Statistically significant improvement from baseline of the ALA, as compared with the placebo group, was also found for each item of the TSS (lancinating and burning pain, asleep numbness and prickling), NIS, one attribute of nerve conduction, and global assessment of efficacy.CONCLUSIONS -Intravenous racemic ALA, a potent antioxidant, rapidly and to a significant and meaningful degree, improved such positive neuropathic sensory symptoms as pain and several other neuropathic end points. This improvement of symptoms was attributed to improved nerve pathophysiology, not to increased nerve fiber degeneration. Because of its safety profile and its effect on positive neuropathic sensory symptoms and other neuropathic end points, this drug appears to be a useful ancillary treatment for the symptoms of diabetic polyneuropathy. Diabetes Care 26:770 -776, 2003T he neuropathies associated with diabetes are heterogeneous (1). Perhaps the most common variety is diabetic sensorimotor polyneuropathy (DSPN), the disorder studied here. This variety appears to be caused by chronic hyperglycemia and associated metabolic derangements, damaging neurons (axons) or Schwann cells (or myelin) directly or indirectly by functional and structural alterations of microvessels or the blood nerve barrier. Inflammation, perhaps from immune mechanisms, may also be implicated in some cases (2).Recognizing that total hyperglycemic exposure may be the most important modifiable risk covariate for diabetic complications such as DSPN (3-8), why search for ancillary treatments in addition to rigorous glucose control? First, despite considerable effort to achieve near euglycemia (by frequent monitoring of plasma glucose, use of multiple injections of insulin, or use of insulin pumps), many ...

OBJECTIVETo evaluate the efficacy and safety of actovegin in patients with diabetic polyneuropathy.RESEARCH DESIGN AND METHODSIn this multicenter, randomized, double-blind trial, 567 patients with type 2 diabetes received 20 intravenous infusions of actovegin (2,000 mg/day) (n = 281) or placebo (n = 286) once daily followed by three tablets of actovegin (1,800 mg/day) or placebo three times daily for 140 days. Total symptom score (TSS) of the lower limbs and vibration perception threshold (VPT) were used as coprimary outcome measures, computed as the area under the curve (AUC) from repeated scores and divided by duration of exposure. Secondary end points included individual TSS symptoms, neuropathy impairment score of the lower limbs (NIS-LL), and quality of life (short form [SF]-36).RESULTSTSS was significantly improved during actovegin treatment compared with placebo, as assessed by AUC (−0.56 points [95% CI −0.85 to −0.27]; P = 0.0003), and from baseline to 160 days (−0.86 points [−1.22 to −0.50]; P < 0.0001). VPT (five sites per foot) decreased by 3% (95% CI 0–6; P = 0.084) with actovegin than placebo, as assessed by AUC, and by 5% (1–9; P = 0.017) after 160 days. NIS-LL sensory function, as assessed by AUC, was significantly improved with actovegin versus placebo (−0.25 [95% CI −0.46 to −0.04]; P = 0.021), as was the SF-36 mental health domain. There were no differences in the incidence of adverse events between the groups.CONCLUSIONSSequential intravenous and oral actovegin treatment over 160 days improved neuropathic symptoms, VPT, sensory function, and quality of life in type 2 diabetic patients with symptomatic polyneuropathy.

Diabetic neuropathy (DN) represents the main cause of morbidity and mortality among diabetic patients. Clinical data support the conclusion that the severity of DN is related to the frequency and duration of hyperglycemic periods. The presented experimental and clinical evidences propose that changes in cellular function resulting in oxidative stress act as a leading factor in the development and progression of DN. Hyperglycemia- and dyslipidemia-driven oxidative stress is a major contributor, enhanced by advanced glycation end product (AGE) formation and polyol pathway activation. There are several polymorphous pathways that lead to oxidative stress in the peripheral nervous system in chronic hyperglycemia. This article demonstrates the origin of oxidative stress derived from glycation reactions and genetic variations within the antioxidant genes which could be implicated in the pathogenesis of DN. In the diabetic state, unchecked superoxide accumulation and resultant increases in polyol pathway activity, AGEs accumulation, protein kinase C activity, and hexosamine flux trigger a feed-forward system of progressive cellular dysfunction. In nerve, this confluence of metabolic and vascular disturbances leads to impaired neural function and loss of neurotrophic support, and over the long term, can mediate apoptosis of neurons and Schwann cells, the glial cells of the peripheral nervous system. In this article, we consider AGE-mediated reactive oxygen species (ROS) generation as a pathogenesis factor in the development of DN. It is likely that oxidative modification of proteins and other biomolecules might be the consequence of local generation of superoxide on the interaction of the residues of L-lysine (and probably other amino acids) with α-ketoaldehydes. This phenomenon of non-enzymatic superoxide generation might be an element of autocatalytic intensification of pathophysiological action of carbonyl stress. Glyoxal and methylglyoxal formed during metabolic pathway are detoxified by the glyoxalase system with reduced glutathione as co-factor. The concentration of reduced glutathione may be decreased by oxidative stress and by decreased in situ glutathione reductase activity in diabetes mellitus. Genetic variations within the antioxidant genes therefore could be implicated in the pathogenesis of DN. In this work, the supporting data about the association between the -262T > C polymorphism of the catalase (CAT) gene and DN were shown. The -262TT genotype of the CAT gene was significantly associated with higher erythrocyte catalase activity in blood of DN patients compared to the -262CC genotype (17.8 ± 2.7 × 10(4) IU/g Hb vs. 13.5 ± 3.2 × 10(4) IU/g Hb, P = 0.0022). The role of these factors in the development of diabetic complications and the prospective prevention of DN by supplementation in formulations of transglycating imidazole-containing peptide-based antioxidants (non-hydrolyzed carnosine, carcinine, n-acetylcarcinine) scavenging ROS in the glycation reaction, modifying the activity of enzymic and non-enzym...

No abstract

Oxidative stress plays a key role in the development of microvascular complications of diabetes mellitus (DM). Antioxidant enzymes protect against the rapid onset of diabetic polyneuropathy (DPN) by reducing oxidative stress. Genetic variations that affect activity or expression levels of the antioxidant enzymes may therefore be associated with susceptibility to DPN. We examined polymorphic markers Ala(-9)Val in SOD2 gene and Arg213Gly in SOD3 gene for possible relation to DPN in Russian type 1 diabetic patients. Four hundred Russian white patients with type 1 diabetes were studied using neurological examination according to recommendations of the San Antonio Conference on Diabetic Neuropathy. Two groups were formed from the general sample. Definition of frequency distribution of the polymorphic markers was performed in these groups using the polymerase chain reaction. Genes encoding the enzymes Mn-SOD and extracellular superoxide dismutase (EC-SOD) were found to be associated with the pathogenesis of DPN.