A 35-year-old man with type 1 diabetes presents with 24 hours of polyuria, polydipsia, vomiting and abdominal pain. He has Kussmaul respirations and appears dehydrated. Capillary glucose is 27 mmol/L, serum ketones are strongly positive and venous pH is 7.12. According to Canadian hyperglycaemic emergency guidelines, which is the most appropriate initial insulin regimen after fluid resuscitation?