Diane Carol Hillyer

Diane Carol Hillyer, 63, of Old Saybrook, Connecticut, passed away peacefully on April 1, 2026, after a courageous 16-month battle with cancer. She fought with the fierce determination that defined her life, leaving behind a legacy of love, dedication, and inspiration.

Diane was born on July 31, 1962 in Wakefield, Massachusetts to the late Grafton and Evelyn Brown. She grew up with her brothers Frank, Bill, and sister Cheryl. In her senior year at Wakefield High School, she was a captain for the women’s gymnastics and track team in her senior year. She earned her BS in Accounting from the University of Lowell in 1983.  She discovered that her true calling was to teach mathematics.  She completed her Master of Education at Central Connecticut State University in 1987.

In 1984, Diane married Clayton L. Hillyer, beginning a loving partnership spanning over four decades. Together, they raised their sons, Clayton and Sam, in South Windsor before moving to Old Saybrook. Her sons remember her unwavering presence - never missing a single game, event, or performance - always cheering them on in whatever made them happy. Diane treasured her role as "Nana" to her grandchildren, Tre and Kiki. She spent countless days with them, filling their time together with joy, happiness, and laughter that will echo in their hearts forever. 

For 37 years, Diane served as a Professor of Mathematics at Manchester Community College, touching the lives of over 10,000 students. She was a passionate educator who cared deeply for her students "I'm not teaching mathematics; I'm teaching human beings. My goal is to help students be successful, whatever their personal or academic goals may be." Her active mentorship helped launch remarkable careers, including that of a Truman Scholar who credited Diane's guidance as foundational to her success.

In 2022, Diane received the Connecticut Science Center's STEM Achievement Award Higher Education Honoree for her advocacy for women in STEM. In 2024, she was crowned Ms. Connecticut Senior America and named a National Finalist, earning Ms. Congeniality - embodying her belief that "life isn't over at 60."

She was grateful to the church community who warmly welcomed her when she moved to Old Saybrook. She served enthusiastically in the choir, dedicated her time and contagious energy to organizing and participating in community events, and compassionately providing help to those in need.

Diane is survived by her husband Clayton, her two sons Clayton and Sam, and her daughter-in-law Shannon (Clayton’s wife), the mother of her beloved grandchildren Tre and Kiki. The world is a dimmer, less joyful place without her in it.

In lieu of flowers, please consider a charitable donation to:  the First Church of Christ in Saybrook 366 Main Street, Old Saybrook, CT 06475 - https://firstchurchsaybrook.org; the Manchester Community College Foundation - https://mccgiving.org; or any charitable organization that helps people in need with dignity.

Diane’s Celebration of Life will be held at 3 pm on Saturday, April 18 at the First Church of Christ in Saybrook 366 Main Street, Old Saybrook, CT 06475.