Glele's own Wikipedia infobox gives no birth date. New World Encyclopedia's Kingdom of Dahomey article, checked as this entity's second source, also gives none. Wikidata states 1814 but is Wikimedia family, not an independent citable source, and no independently reachable source with a checkable citation was found.
What would resolve this A specialist source on Dahomey royal genealogy (e.g. Robin Law's published work on the kingdom) giving a sourced birth year or approximate age at accession in 1858.
OpenWest African history, Dahomey royal genealogyGlele (Wikipedia)