I expect Jill to suggest giving the shot, presumably at 1u, but I'll let her chime in.
On the food side, we are all still concerned because the amount of food you got in is still a small fraction of what he should be eating today. 5.5oz refers to the cat food, which has more energy than the baby food per ounce. 5.5oz cat food is ~200kcals. Karrie's post suggested 2 baby jars is equivalent, but only the larger 100kcal jars. You were able to get in maybe 75kcals from baby food (minus vomit) and maybe another 50kcals from the tuna. It's a good start, but it's not enough yet.
Overnight, you are still trying to get as much food and water in as possible, so leave out what you think he will eat. Fasting causes Feline Hepatic Lipidosis where the body basically poisons itself while trying to use stored fat as the primary food source. The treatment is force feeding, and the prefered food for treatment there is also high-protein, low carb.
With the high BGs, we are also worried about Feline Diabetic Ketoacidosis (DKA), which is where there is not enough insulin to help the body use the glucose it has, plus some added stress kicks the system over the edge. In this case, we are taking about the standard Diabetes treatement (insulin and low-carb food), but you also want as much water as possible to flush the ketones, and the ER would work to get the various electrolyte levels back in balance as well. In emergencies, this means IVs and sub-Q fluids (I know first hand b/c that's what we went through with S'mores)
Because we are worried about both, I don't think you want to go to a high-carb food to entice Baby to eat. Put out his favorite FF, maybe with some extra water to keep it moist.