The reality star, who appeared on MTV's Real World/Road Rules Challenge, passed away at 10:22 a.m. Friday in New York City, according to People.
Diem promoted a message of positivity for people struggling with cancer and other diseases, chronicling her two bouts with ovarian cancer, and again when she was recently diagnosed with colon cancer. The inspirational TV personality first battled ovarian cancer in 2003 at the age of 23 and had to face it again in 2012 when the cancer returned.
After overcoming her second battle with cancer, a bubbly Diem sat down with us back in August 2013, and talked about her public battle with ovarian cancer and why she wanted to inspire others.
"The only way to be able to move forward is to be positive," she told us. "If you become negative, you become a victim. It's hard to succeed when you're a victim, you have to be a champion of your disease and that's something I'm very, very passionate about."
It was Diem's positive attitude that helped her get through the tough times during her first two bouts with the disease. "You are in control," she continued. "You might not be in control of your disease, but you are in control of how you react to it."
During her first bout with cancer, Diem started a website called Medgift.com, a gift registry that provides a community of support for patients and an online listing of a patient's specific needs, wants and wishes during treatment and recovery.
"I created Medgift going through my first round of ovarian cancer, because I needed a wig," she told us. "Medgift is my passion. It's my heart, it's my soul. It's actually my silver lining that got me through cancer the first time.
Sadly, Diem revealed in August that she had been diagnosed with cancer again. After collapsing while filming a new reality show, doctors found cancer in her stomach and colon. In October, it spread to her liver and lymph nodes.
While Diem admitted to People that the diagnosis "really crushed a little bit of my spirit," she stayed determined to beat it, adding, "No matter what it is, you're going to have the bad days, but if you have hope throughout, you won, no matter what the results," she said in October. "Life is so beautiful."