other than angels and around the sun or moon ... no idea
The answer you expect to receive is directly proportional to the amount of information you provide us, we have no idea what your 3 word post is asking. If it's related to diabetes please clearly state what it is; if it was something a doctor told you, why he/she said it, something you read, and so on. For a non-diabetes definition of 'halo' go buy a dictionary or search online for one. Good luck -