The Efficacy And Mechanisms Of Methylcobalamin And Lipoic Acid In The Treament Of Type 2 Diabetes Pweripheral Neuropathy

BACKGROUND:Diabetes is a kind of serious and polular disease which threatened healthy and lives of human. According to the estimates of International Diabetes Federation (IDF) for 2006, there are about 246 million patients with diabetes in the world, and rocketing upward at the rate of 7 million new patients per year. Diabetic Peripheral Neuropathy (DPN) is one of the most common chronic complications of diabetes. China epidemiological investigation in 2001 found that 61.8% type 2 diabetes patients combined with neuropathy. DPN is an public health problem that threaten the life quality of patients with diabetes.Foreign reports of the prevalence of diabetic peripheral neuropathy was 2.4%-75.1%, depending on diagnostic criteria used.There are many ways to diagnose the diabetic neuropathy, but the Nerve Conduction Velocity (NCV), which is unsuitable for extensive screening in clinic because it is not only restrictive but also expensive, is regarded as the gold standard. Generally speaking, the clinical scoring system can quantify and evaluate the severity of diabetic neuropathy, but it is time-consuming and laborious. Therefore, Easy Sensory Testing (EST), simple and economical, is often used to diagnose the DPN in clinic. But it brings a certain problem to the clinical application, because the EST contains different emphasis that results in great difference in the actually diagnostic efficiency. The sensory dysfunction of DPN first appeared, manifestations included positive symptoms (pain, burning, numbness, paresthesia and so on) and negative symptoms (pain sensation, temperature sensation, touch sensation, vibration sensation, loss of tendon reflex and so on) seriously affect diabetes patient's life quality and life. This study will evaluate the clinical value of different EST and use EST to observe the negative symptoms before and after treatment of the patients with DPN, to provide information for clinical.Many pathogenic factors are considered to be involved in the occurance and development of diabetic neuropathy, but it's pathological mechanism is unclear at present. Diabetes Control and Complications Trial (DCCT) and the United Kingdom Prospective Diabetes Study (UKPDS) have already confirmed that hyperglycemia counts for the initial tissue damage of diabetes, which contains four classical channels:activation of Polyatomic Alcohol pathway, Advanced Glycosylation End Products (AGE) pathway and Protein Kinase C (PKC) pathway, and Hexosamine pathway, resulting in peripheral neuronal damage and finally developing DPN. The Reactive Oxygen Species (ROS) generation generally increased in all cell damage induced by hyperglycemia, in view of that, Michael Brownlee puts forward a unified mechanism theory in 2004, that excessive production of mitochondrial reactive oxygen species probably plays an important role in the occurrence and development of diabetic complications. Studies in vivo and vitro have confirmed that hyperglycemia gives rise to the overproduction of mitochondrial ROS in cells and the activation of it can inhibite the activity of Glyceraldehyde-3-Phosphate Dehydrogenase (GAPDH), a key enzyme in the glycolytic glyceraldehyde, to a certain degree. And then upstream metabolites accumulate, glycolytic glyceraldehyde turn to the side way of glucose metalism, which activate the four downstream classical pathway leading to cell dysfunction and endothelial injury and finally resulting in the development of diabetic complications including dibetic neuropathy.DCCT and UKPDS studies have confirmed that strict glucose control can reduce the incidence of diabetic neuropathy and prevent its further development. However, there is no obvious clinical improvement of syptoms in patients with neuropathy only controlling their glucose, therefore combined use of the drugs treating diabetic peripheral neuropathy is nessecery. Methylcobalamin activing the methylation of vitamin B12 is a coenzyme of methionine synthase. It can directly normalize the transportion of axonal structural proteins leading to the regeneration of axonal damaged areas, promote the formation of myelin (phospholipid synthesis), restore the delayed neural velocity and the decreased neural materials. There are many domestic and foreign documents about methylcobalamin as monotherapy or adjunctive therapy for DPN, and it's usage is intravenous or intramuscular injection and oral or intramuscular injection in foreign studies. Most of the literatures evaluate the clinical efficacy by observing the the improvement of subjective symptoms such as lower limb numbness, burning, pain but in clinic methylcobalamin is used for sequential treatment of intravenous or intramuscular injection and oral, and at present there is little documents that evaluate the clinical efficacy by oberserving the negative symptoms such as touchness, painess, temperature sensation, vibration sensation and so on. Alpha lipoic acid (ALA), one of the strongest natural antioxidants, can activate the metabolic cycle of many antioxidants in vivo, form unique biological antioxidant recycling network, maintain the antioxidant levels, and play the role of biological antioxidant together. Most of literatures shows that DPN patients are supposed to be treated with ALA generally for 2～3 weeks injected alone or combinated with other drugs. But it is not certain about whether the short-term treatment of ALA can play the role of oxidative stress and improve the negative symptoms significantly. Currently lots of literatures compared the clinical efficacy of ALA and methylcobalamin, but most were focused on the discrepancy of overrall efficacy treating DPN with two methods, other than on the further analysis of the different efficacy, and whether the sequential therapy of methylcobalamin used as long-term treatment is superior to short-term treatment need further research.The inpatients with type 2 diabetes in Endocrinological and Metabolic Department of Nanfang Hospital from June 1,2010 to November 30,2010 were selected to receive lower limb EST to diagnose DPN, and those with DPN were treated randomly with methylcobalamin and lipoic acid. This study aims to evaluate the clinical value of different EST to diagnose DPN and observe the clinical different efficacy of methylcobalamin and alpha lipoic acid in treating DPN patients. This study will discuss the mechanisms of different effectiveness according to observe oxidatie stress index changes. Specific research includes the following two parts:Part 1 Evaluation of different easy sensory testing in diabetes patients with peripheral neuropathyOBJECTIVE:Evaluate a variety of easy sensory testings (EST) in the diagnosis of diabetic peripheral neuropathy (DPN) and provide basis for the selection of clinical medicine.SUBJECT AND METHODS:1,One hundred and eighty five inpatients with type 2 diabetes, all in line with 1999WHOdiagnostic criteria and classification of diabetes mellitus, in Endocrinology and Metabolism department of Nanfang Hospital from June 1,2010 to November 30, 2010 were chosen, excluding cervical lumbar, infectious polyneuritis, chronic alcoholism, thyroid disease, drugs, poisoning, cancer and peripheral neuropathy caused by heredity and so on.2,Use Toronto Clinical Scoring System (TCSS) as the standard for DPN. All patients were checked for TCSS and EST, including lOg monofilament, pinprick sensation, temperature sensation, vibration perception threshold.3,Joint Inspection:Parallelled testing was used to improve the screening sensitivity. Using lOg monofilament,40g pinprick sensation, temperature sensation and vibration perception threshold diagnosed of joint screening inspection, and one positive was defined as positive.4,Use the statistical software SPSS 13.0, and Spearman rank correlation analysis were carried out between different kinds of EST and TCSS rating scale, respectively. Fourfold table was used to analyse the sensitivity, specificity, accuracy, Youden index and Kappa values of DPN diagnosed by single EST and two EST combined. The Youden index was used for evaluatng the validity of screening methods andκvalues for the reliability and consistency.RESULTS:1,The results showed that TCSS was positive correction with 10g monofilament, pinprick sensation, temperature sensation, vibration perception threshold and two EST combined with (P=0.000). The most significant correlation was found betw-een TCSS and lOg monofilament combined with temperature sensation (r=0.560).2,Using the TCSS score scale as a standard, Youden index andκvalue were monofilament 44.67%,0.465; pinprick sensation 40.66%,0.399; temperature sensation26.13%,0.278; vibration perception threshold 19.29%,0.208; 2 EST combined Youden index andκvalue were monofilament combined pinprick sensation 47.76%,0.461; monofilament combined temperature sensation 54.70%, 0.555; monofilament combined vibration perception threshold 46.89%,0.482; pinprick combined temperature sensation 41.16%,0.402; temperature combined vibration perception threshold 30.48%,0.323; pinprick combined vibration perception threshold 38.72%,0.379.CONCLUSIONS:In this study, the method of 10g monofilament combined with temperature sensation has the highest validity and reliability in diagnosing DPN. So it is recommended to use in outpatient and inpatient clinical practice to make routine physical examination and observe the change of patient's condition.Part 2 The efficacy and mechanisms of methylcobalamin and lipoic acid in the treatment of type 2 Diabetes Peripheral NeuropathyOBJECTIVE:To observe the different efficacy and mechanisms of methylcobalamin and lipoic acid in the treatment of type 2 Diabetes Peripheral Neuropathy and provide informati-on for clinical drug selection.SUBJECT AND METHODS:1,A total of 40 inpatients with type 2 diabetes in Endocrinology and Metabolism department of Nanfang Hospital from June 1,2010 to November 30,2010 were selected, of these 40 patients finished the follow-up 2weeks after treatment,17 patients 6weeks after treatment (3 cases lost to follow-up) and 16 patients 12weeks after treatment (4 cases lost to follow-up). Inclusion criteria:(1) All in line with 1999 WHO diagnostic criteria and classification of diabetes mellitus; (2) TCSS> 5; (3) HbAlc> 7.0%; (4) Stop drug treatment of diabetic neuropathy at least 2 wee-ks; (5) Age 18 to 65 years of age. Exclusion criteria:(1) pregnancy, for pregn-ancy or breast-feeding women; (2) exclude following diseases:a) cervical lumbar, infectious polyneuritis, chronic alcoholism, thyroid disease, drugs, poisoning, cancer, cerebrovascular sequelae, osteoarthritis, peripheral vascular disease, and peripheral neuropathy caused by gene and so on; b) foot ulcers, infection and edema; c) ABI <0.9; d) patients whose ALT, AST more than 2.0 times upper limit of normal or Cr over upper limit of normal; (3) with severe organ disease or combined with other severe primary disease, mental illness, poorly controlled hypertension (blood pressure of the patients treated with antihypertensive drugs more than 160/100 mmHg); (4) develop ketosis, ketoacidosis, and severe infection within two weeks; (5) have bleeding or bleeding tendency within the past 2 months; (6) allergy; (7) patients who does not match, can not meet, or can not comply with treatment; (8) the patients who are considered to be not suitable to participate in the trials by researches.2,The patients were randomly divided into two groups to receive methylco-balamin (1000ug iv 1/d for 2weeks and then 500ug oral 3/d for 10weeks) for 12 weeks orα-lipoic acid (600mg ivgtt 1/d for 2weeks) and their value of TCSS, TSS, VAS, EST (10g monofilament, pinprick sensation, temperature sensation and vibration perception threshold), blood glucose, GSP, HbAlc, MDA, and SOD were recorded before and after treatment. Basic therapy were all patients using the insulin pump to control glucose,2 weeks after methylcobalamin groups change to oral medicine continue to control glucose.The target were 7.0 mmol/L of fasting blood glucose and 10.0mmol/L of postprandial blood glucose and both groups using prostaglandin lOug ivgtt 1/d for 2weeks.3,Using software SPSS13.0 to complete statistical analysis, measurement data were indicated by x±s,compared by t test or chi-square test. Chi-square test was used to compare two independent samples and paired sample t test or Wilcoxon test before and after treatment. Repeated measurement data using One-way Repeated Measurements ANOVA or the Friedman test and Cochran's Q test, there was significant difference statistically if only P<0.05.RESULTS:1,There was no significant difference in sex, age, disease duration, FBG, HbAlc, urine albumin/urine creatinine (ACR), low density lipoprotein (LDL) triglycerides (TG), systolic blood pressure, diastolic blood pressure, TCSS and TSS score between two groups before treatment (P>0.05)2,The TCSS and TSS score were significantly decreased 2weeks after treatment as compared with before treatment (P<0.01), while there was no obvious difference in the differnent value and the change rate of TCSS and TSS score between the two groups 2weeks after treatment (P>0.05). The GSP had no statistical difference in two groups before treatment and 2weeks after treatment (t=-0.763,-0.525 and P= 0.450, 0.602 respectively)3,The pain, burning, numbness and paresthesia VAS score were no obvious difference before treatment between the two groups (P>0.05); VAS score of positive symptoms decreased significantly 2weeks after treatment compared with before treatment (P<0.05 or P<0.01) in two groups. The change rate absolute value of numbness and paresthesia in methylcobalamin group was higher than that in lipoic acid group, but with no statistical difference (t=-0.151,-0.448 and P=0.880,0.657 respectively). The change rate absolute value of VAS burning score in lipoic acid group was significantly higher than that in methylcobalamin group (t=3.048, P 0.008). The change rate absolute value of VAS pain score in lipoic acid group was higher than that in methylcobalamin group, but there was no statistical difference (t=2.087,P=0.055)4,In methylcobalamin group,2weeks after treatment, monofilament and pinprick sensation abnormal points, vibration perception threshold improved significantly compared with that before treatment (P<0.05), but there were no significant improvement of temperature sensation and tendon reflexes (P>0.05). In lipoic acid group,2weeks after treatment monofilament, pinprick sensation abnormal points, temperature sensation and tendon reflexes didn't improved compared with that before treatment (P>0.05), while vibration perception threshold tests improved significantly (t=2.822, P=0.011).There was no significant improvement of vibration perception threshold rate of change between the two groups (t=0.027, P=0.979).5,There was no significant difference in MDA and SOD in methylcobalamin group 2weeks after treatment compared with that before treatment (t=-0.215,0.424 and P=0.832,0.676 respectively). MDA in lipoic acid group decreased significantly 2weeks after treatment compared with that before treatment (t=-2.651, P=0.016) and SOD changes in a similar way (t=2.778, P=0.012)6,The score of TCSS and TSS decreased significantly in methylcobalamin sequential therapy after treatment at 2weeks,6weeks,12 weeks (P<0.05 or P<0.01).7,The VAS scores of pain, numbness, paresthesia decreased significantly in methylcobalamin sequential therapy after treatment at 2 weeks,6 weeks,12 weeks compared with that before treatment (P<0.05 or P<0.01). VAS score of burning was significantly decreased than after treatment at 2 weeks compared with that before treatment (P=0.041), while no significant difference after treatment at 6 weeks and 12 weeks (P=0.289,0.497 respectively)8,The efficency of pain and numbness increased gradually in methylcobalamin sequential therapy 2 weeks,6 weeks,12 weeks after treatment.The efficeney of paresthesia symptoms up to maximum after treatment at 12weeks (86.67%), while burning sensation at 2 weeks (77.78%)9,The monofilament abnormal feeling points reduced significantly in methylco-balamin group after treatment at 2 weeks and 12 weeks compared with that before treatment (P=0.013,0.048 respectively); 2 weeks,6 weeks and 12 weeks after treatment abnormal pain points decreased significantly (P<0.05 or P<0.01); 6 weeks and 12 weeks after treatment vibration perception threshold decreased significantly (P=0.011,0.001 respectively); while temperature sensation and tendon reflex with no significant difference (P>0.05)CONCLUSIONS:In this part, short-term treatment of methylcobalamin and alpha lipoic acid combi-nation with prostaglandin can significantly improve positive and a certain negative symptoms of peripheral neuropathy in patients with type 2 diabetes, but the degree of improvement vary according to symptoms. Sequential treatment with Methylcobala-min can further improve some clinical symptoms except for burning sensation, temperature sensation, and tendon reflexes. This study suggests that methylcobalamin and lipoic acid as two DPN treatment drugs are common used in clinical, but their effectiveness may exist different focus. Therefore they are selected to use according to the actual situation of patients.