Regardless of the type of diabetes you have, your body needs to clear sugar from bloodstream. It really does not matter how this happens, exactly. Insulin performs other functions in your body... but ability to clear sugar is the absolutely most vital concern.
If you can do things that either prevent or clear blood sugar levels from your bloodstream you can technically live without the need for insulin at all.
With a proper diet and discipline you can theoretically even dispense with continuous monitor. What this would require is observing yourself with a monitor while you test your lifestyle choices to validate you are not making mistakes and then stop using it when you trust what you are doing is effective.
Please, do not misconstrue this as an actual medical advice (I am a software developer and definitely no medical education). But if I was type 1 diabetic I would probably try to ensure correct levels of sugar without external insulin. The problem with external insulin is that the dosage is always delayed, it is a point in time and is never perfect. This is not perfect for your health, it is just the best we can.
Now, I would never recommend this to a person I don't know they can be responsible and disciplined enough not to endanger themselves this way. I think this is critical and I also think that unfortunately most people who have diabetes are not fit mentally to do this.
But lowering your blood sugar without insulin would lead to much better results because you would avoid the spikes altogether and you would not risk getting sensitive to insulin from overdosing it.
FYI when I am on keto diet my blood sugar levels are staying consistently low regardless of how much I eat. I have lower blood sugar levels right after a large meal than most people have before the meal(~85mg/dL or 4.7mmol/L after a meal with ~75mg/dL or around 3.9mmol/L before the meal).
I do not plan to stay on keto all the time, I am using it as a tool to build metabolic flexibility. But if I was diabetic I would probably consider keto very seriously to improve my prospects and break dependency on external insulin, constant blood sugar monitoring and every day decisions on what and how much to eat.