Here’s the thing that complicates this for people with functioning beta cells… There is a degree of “substitution” that takes place, so the effect basal levels of exogenous insulin has on T2s can be quite variable, and non-linear from person to person.
When doing drug trials on long-acting insulins they have non-diabetics in the control group. A perfectly normal person can take a low-dose basal injection daily with no effect at all – their pancreas just excretes less insulin.
I personally experience this as a T2 – I have my basal set to 0.05U/hr on my pump most of the day because my own pancreas can handle the job. I can turn it up at high as 0.5U/hr (10x) without any impact on my BG.
What my pancreas CAN’T handle are the increased basal needs in the morning and the evening, where I have to crank it up to 2U/hr for several hours.
And, of course, the large amount necessary when digesting a meal…