Why insulin is so expensive

Colorado became the first state to pass a bill capping the monthly cost of insulin per resident at $100. 
Type 1 diabetics need insulin to survive. Due to drastic price increases, many diabetics are struggling to afford the lifesaving drug. 
In the past 15 years, insulin prices have tripled. There are only three manufacturers who make insulin and decide the price for insulin — their prices have risen at the same rates.
The insulin supply chain, like other pharmaceutical medicati