I'm aware that there's a lot of stuff out there that says OMFG! Vitamin D deficiency is awful, will kill you, and all sorts of horrible things!
I've long been skeptical of such claims. One thing that bothers me is how all sorts of things, including minor vitamin deficiencies, or variations in some clinical findings, have been medicalized. If your blood sugar or blood pressure or cholesterol levels are not within a very narrow range, (and that range has been narrowed in recent years) then you need to be treated or take medication! Really? Why am I so skeptical?
In a side note, I heard on NPR a couple of days ago that since the Corona Virus lockdown, premature births have dropped significantly.
Hmmm.
Another side note. I rarely, if ever, go to doctors. A while back, when needing to pass a physical for a life insurance policy, I was diagnosed with high blood pressure. So to qualify for the policy, I took medications. I also had high cholesterol, which I'd known about for some years, but I also know that high cholesterol is not the boogy man it's claimed to be. After a while, when my doctor wanted to add a fourth medication to the three I was already taking, I balked. Stopped seeing her. Stopped the meds. I no longer have the slightly disagreeable side effects from the meds, and overall I'm the healthiest person I know. Especially at my age, 71. In all honesty, I'm constantly amazed and appalled at how many people my age and a lot younger seem to have serious medical conditions, take lots of medications, and can barely function. It's scary.
I am not about to suggest you stop taking insulin or any other medication. But I will say that if you get to the point where you need to take a medication to counter the side effects of some other medication, you are probably taking at least one too many meds.