The Effect Of Plasma Homocysteine Level On Diabetic Peripheral Neuropathy

Objective: Diabetic peripheral neuropathy (DPN) is a major complication of diabetes mellitus (DM), a high incidence and the treatment is difficult. In recent years, numerous studies have proved that hperhomocysteinemia is a risk factor to DPN. This study was to further investigate the effect of plasma total homocysteine level on diabetic peripheral neuropathy.Methods: 110 DM cases who met the 1999 WHO diagnostic criteria of diabetes patients, this patients were informed the purpose and the content of this study and signed informed consent. Their sensory and motor conduction velocity of right limb median nerve, ulnar nerve, tibial nerve, the common peroneal nerve, were measured by EMG evoked potential instrument; the amplitude was measured at the same time. According to the results, 90 cases were selected; their nerve conduction velocity or nerve conduction amplitude was abnormal. Their folic acid, vitaminB₁₂, HbAlc, mAlb, FBG, and plasma total homocysteine level were measured. According to plasma total homocysteine level ,the 90 cases were divided into two groups: group A (40 patients) tHcys≤15μmol/L; group B (50 patients) tHcy>15μmol/L. The two groups of patients with good blood glucose control (HbAlc <7%), their hepatic and renal function was normal, and no acute infection.Results: 1. The patients of DM with DPN were 90 in all cases, the incidence rate of DPN was 82%. 2. There was no significant difference in nerve conduction velocity and amplitude of median nerve, ulnar nerve, between the two groups. 3. There was also no significant difference in motor conduction velocity and amplitude of tibial nerve, common peroneal nerve. 4. Tibial nerve sensory conduction velocity, group B (10.40±3.03) m/s was significantly slower than group A (23.65±2.14) m/s, P <0.05. 5. Tibial nerve sensory conduction amplitude, group B (0.34±0.09) uV was significantly lower than group A (1.14±0.46) uV, P <0.01. 6. Common peroneal nerve sensory conduction velocity, group B (12.16±4.16) m/s was significantly slower than group A (26.70±3.46) m/s, P <0.05. 7. Common peroneal nerve sensory conduction amplitude, group B (0.32±0.07) uV was significantly lower than group A (1.07±0.35) uV, P <0.01. 8. The level of folic acid compared between the two groups, group B (10.50±3.73) ng/ml was significantly lower than group A (17.64±1.27) ng/ml, P <0.01; the difference of VitB12 between the two groups was not significant, P> 0.05. Correlation analysis showed that tHcy was positively correlated with course, FBG, HbAlc (r 0.840,0.675,0.315, P <0.01); and negatively correlated with folic acid, VUB12 (r -0.677, -0.562, P <0.01). THcy was negatively correlated with sensory conduction velocity and amplitude of tibial nerve, common peroneal nerve. Folic acid was positively correlated with sensory conduction velocity and amplitude of tibial nerve, common peroneal nerve.Conclusion: 1. DPN is an important complication of diabetes, the incidence rate was about 82%. 2. The most common peripheral nervous system symptoms of DPN was numbness, followed by the spontaneous pain. The proportion of lower extremity nerve damage was higher than upper extremity, powerless and pain of lower extremity was more obvious than upper extremity. 3. With the increase of plasma total homocysteine level, the patients of DPN, their lower extremity sensory nerve injury was aggravated, suggesting that high level of tHcy increased lower extremity sensory conduction fibers myelin and axonal injury. 4. Folic acid was positively correlated with sensory conduction velocity and amplitude of tibial nerve, common peroneal nerve, suggesting that folic acid supplement would be helpful to the repair of tibial nerve and common peroneal nerve injury.