Limited evidence suggests that both vitamin B12 (B12) and homocysteine (Hcy) status are impacted by metformin use and may be associated with diabetes complications. The goal of this research project was to assess the cross-sectional association between B12 and Hcy status and kidney function and neuropathy among patients with type 2 diabetes (T2D) taking metformin. Adult patients in an academic primary care clinic (n = 52; mean age = 53 ± 12.5 years; female 56%; African American 70%) with T2D (mean duration = 9.8 year) and taking metformin (mean duration = 9.2 year) provided informed consent and had blood and urine specimens drawn for: A1c, B12, Hcy, serum creatinine (sCr), urine albumin/creatinine ratio, and eGFR. Neuropathy was assessed using the validated Michigan Neuropathy Screening Instrument. Mean B12 and Hcy levels were 568.7pg/ml and 12.85 µmol/L, respectively. Serum B12 was significantly correlated with Hcy (r = -0.3, p = 0.035) and with A1c (r = 0.36, p = 0.01). Hcy was significantly correlated with both sCr (r = 0.70: p = 0.0001) and eGFR (r = -0.68; p = 0.0001). While B12 was not directly correlated with either diabetes duration or duration of metformin therapy, the correlation of B12 with total metformin exposure (dose x years) approached significance (r = -0.26; p = 0.06). There was no relationship of either B12 or Hcy with neuropathy scores. The bivariate relationship of B12 and Hcy to renal function measures was not different in patients with a diabetes duration of less than 10 years vs. 10 or more years. Consistent with previous studies our findings suggest that B12 status, in addition to correlating with renal function, correlated with glycemic control. Periodic measurement of B12 status should be considered in metformin-treated patients with T2D.


S. Patil: None. R. Pawlak: None. A. Thombare: None. R. Baltaro: None. K. Hicks: None. D.M. Cummings: None.

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