Fr. Glenn was raised in Branchburg, graduated from Somerville High School and pursued a career as a Spanish and French teacher. His B.A. in Spanish and French was awarded summa cum laude from Montclair State University in 1978. That same year, he was the recipient of a Fulbright-Hayes Teaching Assistantship to France where, for one year, Comandini was assigned a position teaching English grammar and American Civilization at the Lycee Joffre in Montpellier.

Upon his return, he entered graduate school at the University of New Mexico where he received the M.A. in French. It was during this time in the desert that Fr. Glenn discerned his vocation to the priesthood which, under the direction of his mentor in Albuquerque, resulted in his acceptance by then Bishop McCarrick as a candidate for the seminary for the newly erected Diocese of Metuchen. In 1986, after four years at Mt. St. Mary's Seminary in Emmitsburg, Maryland. Glenn was awarded the Masters of Divinity as well as the M.A. in Theology. On May 31, 1986 he was ordained a priest and assigned to advanced studies in Systematic Theology at the Pontifical Gregorian University in Rome. With his background in French, it was no surprise that he perused the writings of a little-known theologian from Dijon by the name of Jean Mouroux, who wrote just five books and sixty articles in the 1940's and 50's. His interest was on discovering how St. Thomas Aquinas' supernatural existential, the writings of philosopher Maurice Blondel, Jacques Maritain, as well as the early twentieth-century thought of both Rousselot and Marechal influenced this French priest-professor. Fr. Glenn decided to write his dissertation on Mouroux's theology of the body, which he successfully defended on May 26, 1990.

Upon his return to the United States, then Bishop Hughes assigned Comandini as Parochial Vicar of Our Lady of Perpetual Help in Bernardsville. It was at this time that he also began teaching part-time at Seton Hall University - a post he held on and off for six years. In 1992, Bishop Hughes asked Fr. Glenn to learn Portuguese - which required weekly visits to a Portuguese parish in Elizabeth as well as summer in a parish in Portugal. That September, he became Pastor of St. Stephen Protomartyr Church in South River. During his pastorate, he offered the Portuguese Mass monthly at Corpus Christi Church in the same town. He also became Chaplain of the fire department and continued teaching part-time at both Seton Hall and the College of St. Elizabeth. For several years, Comandini taught the Spanish tract of the theology courses required by the diaconate formation of the Diocese of Metuchen.

In 1998, then Bishop Breen asked Fr. Glenn to take on a three-year position as Episcopal Vicar for the City of Perth Amboy and, concomitantly, a six-year term as Pastor of Our Lady of the Most Holy Rosary parish in Hopelawn. There he also volunteered his services as Chaplain of the Perth Amboy Police Department. He also initiated a Spanish/French program into the curriculum of the Perth Amboy Catholic School where he taught both languages for three years. In 2001, Commandini also began teaching religious studies part-time for St. John's University in New York.

In the Diocese of Metuchen, Fr. Glenn has held numerous positions including Chairman of the Commission for Ecumenism, Director of the Office for Multicultural Ministries, Bishop's Delegate on the Ethics Committee of St. Peter's University Hospital, Censor Librorum Chair of the Hispanic Commission and Chair of the Theological Commission.