Can necessary medication be permissible even if it contains haram ingredients?

I don't mean to bother you. I am not Muslim, but I have deep respect for your faith and work and study with Muslims on an almost daily basis. I have noticed that some of my Muslim friends do not eat certain foods. Can truly necessary medications--insulin, for example--be exempt from Muslim dietary rules? I know God would never want a person to actively harm or kill him- or herself without very, very good reasons. I have learned that people who are ill or very elderly are not expected to fast during Ramadan, and people are asked to go on the hajj only if they can afford it. My true interest is the core of Islam. As a Quaker, I believe any religion that leads a person to find the love and truth within and live it with all people has something precious from which I can learn and enrich my own faith. I was just curious about the dietary laws.