For me personally, critical thinking and good nursing judgement would come in to play considering I knew the patient well. I am pretty sure in the middle of the night, the MD doesn't care whether you held the insulin or not. But, knowing I had a crazy supervisor that was going to blow up the whole situation, I would notify the MD. And while I was at it, I would ask him for some parameters in which to hold the insulin in the future. A part of being a good nurse is to learn from your mistakes. Always be on your toes and consider every aspect of the decisions that you make.