I don't see any evidence that it's a bad idea, but from poking around I get the feeling that there is still a lot about it that we don't know. For instance, it

I don't see any evidence that it's a bad idea, but from poking around I get the feeling that there is still a lot about it that we don't know. For instance, it may be monkeying around with blood flow to the kidneys somehow. "Among patients with diabetic nephropathy, high doses of B vitamins compared with placebo resulted in a greater decrease in GFR and an increase in vascular events." https://jamanetwork.com/journals/jama/fullarticle/185758 https://jamanetwork.com/journals/jama/fullarticle/185758 House AA, Eliasziw M, Cattran DC, et al. Effect of B-Vitamin Therapy on Progression of Diabetic Nephropathy: A Randomized Controlled Trial. JAMA. 2010;303(16):1603–1609. doi:10.1001/jama.2010.490 So, it's probably fine, but honestly nobody really knows.