Homeopathy doesn't have any side effects. Yes it can be helpful in cases of kidney n diabetes but then it's efficacy depends on how complicated the case is or on how gross the disease has grown. About renal failure case u read online, I don't think Homeopathy must have complicated it, a patient in renal failure is eventually going to get bad. In such case Homeopathy works just as palliative because the structural changes are irreversible. Hope this information is helpful to u.