How can my husband convert from a daily insulin schedule, to a nightly one?

Basal insulin?: If you mean a basal Insulin such as lantus, (insulin glargine) you just switch to taking it at night, even though you took a show that morning. There will be some overlap for the first 24 hours and you will have to monitor for increased possibilities of hypoglycemia during that first day, but after that it should stabilize. There will be slight differences in action when you change the timing, however.