1.
Monitoring Vitamin B12 in Women Treated with Metformin for Primary Prevention of Breast Cancer and Age-Related Chronic Diseases.
Mastroianni, A, Ciniselli, CM, Panella, R, Macciotta, A, Cavalleri, A, Venturelli, E, Taverna, F, Mazzocchi, A, Bruno, E, Muti, P, et al
Nutrients. 2019;(5)
Abstract
Metformin (MET) is currently being used in several trials for cancer prevention or treatment in non-diabetics. However, long-term MET use in diabetics is associated with lower serum levels of total vitamin B12. In a pilot randomized controlled trial of the Mediterranean diet (MedDiet) and MET, whose participants were characterized by different components of metabolic syndrome, we tested the effect of MET on serum levels of B12, holo transcobalamin II (holo-TC-II), and methylmalonic acid (MMA). The study was conducted on 165 women receiving MET or placebo for three years. Results of the study indicate a significant overall reduction in both serum total B12 and holo-TC-II levels according with MET-treatment. In particular, in the MET group 26 of 81 patients and 10 of the 84 placebo-treated subjects had B12 below the normal threshold (<221 pmol/L) at the end of the study. Considering jointly all B12, Holo-TC-II, and MMA, 13 of the 165 subjects (10 MET and 3 placebo-treated) had at least two deficits in the biochemical parameters at the end of the study, without reporting clinical signs. Although our results do not affect whether women remain in the trial, B12 monitoring for MET-treated individuals should be implemented.
2.
An observational study of vitamin b12 levels and peripheral neuropathy profile in patients of diabetes mellitus on metformin therapy.
Gupta, K, Jain, A, Rohatgi, A
Diabetes & metabolic syndrome. 2018;(1):51-58
Abstract
METHODS A descriptive, observational study was completed in a tertiary care hospital between November 2014 and March 2016. Fifty consecutive patients of Type 2-Diabetes Mellitus who had been on metformin therapy for at least three months were included in our study. Several Parameters were compared with vitamin B12 levels and severity of peripheral neuropathy (using Toronto Clinical Scoring System (TCSS) and Nerve Conduction Velocity). These included the duration of diabetes, duration of metformin usage, dietary history, and HbA1c levels. Definite B12 deficiency was defined as B12<150pg/ml and possible B12 deficiency as <220pg/ml. RESULTS In our study, we found a negative correlation between duration of metformin use and Vitamin B12 levels(r=-0.40). The mean Vitamin B12 levels seen in our study was 212.3pg/mL. There is a positive correlation between the duration of metformin therapy and peripheral neuropathy (r=0.40). The mean TCSS score was 6.8. The percentage of patients with mild neuropathy was 28%, with moderate neuropathy was 20% and severe neuropathy in 12% of the patients. The average duration of metformin use in patients without peripheral neuropathy was 5.5yrs whereas the average length of metformin use in patients with peripheral neuropathy was 10.4 yrs. CONCLUSION Patients on long-term metformin therapy are at a high risk for Vitamin B12 deficiency and peripheral neuropathy. Interval Screening for peripheral neuropathy is recommended for patients on metformin even if Vitamin B12 levels appear to be normal.