I can’t help this particular enquiry as I’m not an insulin user. But as no one else has answered yet I didn’t want you to feel ignored. Hopefully someone with more specific knowledge will be along soon.
It does sound like he needs to revisit his regime with his drs though. Fixed doses on a set schedule are incredibly limiting and force you to eat the same type of foods at the same time. A problem in situations like today. A basal bolus option (in essence one long acting injection for background needs and then short acting ones for food) allows you to adjust what and when you eat and change your medication yourself to suit your day. Many insulin users report better control this way too. These days fixed doses are usually switched to the more flexible option after a short while post diagnosis and being stuck long term on them isn’t the most favoured option and is a bit old fashioned - unless there’s good reason to stick with that choice of course.