Well, well. Here's the American Diabetes Association survey from 2018; it did find that too many people struggle with the cost of insulin.
But. Go to slide 17 and what do we find? The highest number of people struggling to afford insulin are on..........Medicare and Medicaid. Government single payer programs. The best category for people NOT struggling are people on private, employer based health insurance.
You're right. Let's expand Medicare to everyone, that way the entire country can struggle to afford insulin.
http://main.diabetes.org/dorg/PDFs/2018-insulin-affordability-survey.pdf