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| Year : 2014 | Volume
: 60
| Issue : 1 | Page : 96-97 |
Comment on: Association of B12 deficiency and clinical neuropathy with metformin use in type 2 diabetes patients
MN Chowta, G Tiwary
Department of Pharmacology, Kasturba Medical College, Manipal University, Mangalore, Karnataka, India
| Date of Web Publication | 14-Mar-2014 |
Correspondence Address:
M N Chowta
Department of Pharmacology, Kasturba Medical College, Manipal University, Mangalore, Karnataka
India
 Source of Support: None, Conflict of Interest: None  | Check |
PMID: 24625957 
How to cite this article:
Chowta M N, Tiwary G. Comment on: Association of B12 deficiency and clinical neuropathy with metformin use in type 2 diabetes patients. J Postgrad Med 2014;60:96-7 |
How to cite this URL:
Chowta M N, Tiwary G. Comment on: Association of B12 deficiency and clinical neuropathy with metformin use in type 2 diabetes patients. J Postgrad Med [serial online] 2014 [cited 2023 May 31];60:96-7. Available from: https://www.jpgmonline.com/text.asp?2014/60/1/96/128837 |
Sir,
With reference to the aricle on 'Association of B 12 deficiency and clinical neuropathy with metformin use in type 2 diabetes patients, we would like to put forth our views. [1] The article by itself has no new message. Several studies have examined this association and the mechanisms involved. In addition, the design used by the authors may not be sufficient to prove a cause-effect relationship. Exhaustion of vitamin B 12 stores usually occurs after 12 - 15 years of absolute vitamin B 12 deficiency. Hence, the duration of therapy with metformin is an important parameter to be considered. In addition, the authors have not compared the duration of diabetes among those taking metformin versus those not taking metformin, although they mention that data regarding the duration of diabetes had been collected. The duration of disease is thus a major confounding factor, as it increases the chances of peripheral neuropathy, which by itself is a complication of the disease. Hence, two groups must be comparable with regard to duration of disease too. Many diabetic patients are also likely to receive vitamin supplementation, which has not been addressed. Absorption of the vitamin B 12 -intrinsic factor complex is calcium-dependent and metformin interferes with this absorption. In support of this hypothesis, there is evidence that dietary calcium supplementation reverses metformin-induced vitaminB 12 malabsorption. [2] Hence, patients taking calcium supplementation also need to have been excluded. Similarly, there are many other medications that can cause vitamin B 12 deficiency. Also, the use of the Toronto Clinical Scoring system (TCSS) does not address bias adequately (Investigator blinded only to the laboratory results, but not to the group allocation). Another finding is that the number of patients having neuropathy was much more than the number of patients having vitamin B 12 deficiency (44 vs. 25 in the metformin-treated group). This discrepancy definitely points to other causes of peripheral neuropathy in these patients, as expected (diabetic neuropathy). [Figure 1] in the article has shown the correlation of cumulative doses of metformin with vitamin B 12 deficiency with out mention of the unit.
| :: References | |  |
| 1. | Singh AK, Kumar A, Karmakar D, Jha RK. Association of B12 deficiency and clinical neuropathy with metformin use in type 2 diabetes patients. J Postgrad Med 2013;59:253-7. 
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| 2. | Bauman WA, Shaw S, Jayatilleke E, Spungen AM, Herbert V. Increased intake of calcium reverses vitamin B12 malabsorption induced by metformin. Diabetes Care 2000;23:1227-31.
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| Singh, A.K., Kumar, A., Karmakar, D., Jha, R.K. | | Journal of Postgraduate Medicine. 2014; 60(1): 97 | | [Pubmed] | |
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