Diabetic neuropathy is the most common and debilitating microvascular complication leading to nontraumatic amputations. Identifying the role of vitamin B12 in the etiology of neuropathy is crucial because simple vitamin B12 replacement may reverse neurologic symptoms if confirmed. Large proportion of vegetarians and patients on metformin have been associated with lowering of vitamin B12 levels. We have undertaken study on 60 vegetarian subjects between the age of 30 and 60 years, 20 healthy controls, 20 type 2 diabetes mellitus patients who were on metformin with peripheral neuropathy (DMWN), and 20 diabetics without peripheral neuropathy (DMWON). Vitamin B12, homocysteine, and folate levels were measured, and holotranscobalamin (holoTC) is also included, to improve the diagnosis of tissue vitamin B12 status, as holoTC is the biologically active fraction and more sensitive index of vitamin B12 status than total vitamin B12 itself. Complete history and clinical evaluation for neuropathy and electroneuromyography were recorded.
Results: In the DMWN group, vitamin B12 levels were significantly higher than in the DMWON group and controls [1013 (564-1501) pmol/l, 387 (245-731) pmol/l, and 305 (234-472) pmol/l respectively]. Similarly, serum holoTC was also found to be significantly higher in the DMWN [203.8 (129-300) pmol/l] group compared with the DMWON [94.4 (42.2-230.6) pmol/l] group and controls [74 (40-170) pmol/l]. Whereas mean levels of homocysteine and folate did not show any significant difference between groups, significant increase in fasting blood sugar and HbA1c was seen in the DMWN group compared with DMWON group and controls. Duration of diabetes is also significantly more in DMWN group compared with DMWON group.
Conclusion: We found that vitamin B12 and holoTC levels were high in patients with DMWN and DMWON groups compared with controls. Our study demonstrated that peripheral neuropathy was not associated with vitamin B12 deficiency in diabetics. These findings merit further research on a larger population to investigate into the cause of diabetic neuropathy, the factors involved, and benefit of vitamin B12 supplementation in these patients.
Key messages: Vitamin B12 status has no association with diabetic peripheral neuropathy.
Keywords: Diabetes mellitus, Holotranscobalamin, Peripheral neuropathy, Vitamin B12.
How to cite this article: Noorjahan M, Madhavi K, Priscilla C, Jabeen SA. Vitamin B12 and Holotranscobalamin Levels in Diabetic Peripheral Neuropathy Patients. Indian J Med Biochem 2016;20(1):16-20.
Source of support: Nil
Conflict of interest: None