BUTTER AND INSULIN Like a lot of diabetics, I keep my insulin in one of the shelves in my fridge door. While I try to keep the butter separate, it does often end up mixed in. In case you're trying to read labels, there's a box of Lantus SoloStar pens, vials of Lantus, and boxes of NovoLog pens. I keep the insulin in my fridge until I'm ready to use it, then try to take it out the night before so it has a chance to warm up a bit. I hate injecting cold insulin.