No, not automatically — though it narrows the field and moves most files at least a step. Carriers that specialise in diabetic business treat insulin very differently from carriers that do not.
Insulin use is one of the most misunderstood factors in diabetic underwriting, largely because the conventional wisdom is a decade out of date.
What changed
Insulin is no longer treated as an automatic table rating. Practitioners report that onset after age 40 with a stable A1c can still reach competitive term pricing. What insulin does reliably is narrow the list of carriers worth approaching.
Why it still moves the file
Insulin-dependent type 2 is harder to place than type 2 managed on oral medication alone, because it tends to signal progression rather than simply a different treatment choice. Underwriters read it as information about trajectory.
What to do about it
If you use insulin, working with an agent who knows which carriers write insulin-dependent files is worth more than any other single step. The difference between the right carrier and the wrong one is larger here than the difference a modest A1c improvement would make.
The full treatment of this topic is on Diabetes.