Glasenberg had discussed his succession plan in recent meetings, Bloomberg reported, citing people familiar with the matter.
He believed the next leader should come from a younger generation, the wire service said, adding the comments put a timeline on the CEO's exit for the first time and force investors to consider what has long seemed unthinkable: a Glencore without Glasenberg.
Glasenberg, who turns 62 in January, worked as an accountant before joining Glencore in 1984.
He has been CEO of the global diversified miner and commodities trader since January 2002.
The company is part of the FTSE100 index, where its share price has fallen 16.73% year-to-date as it has faced challenges including a subpoena from US Department of Justice over its business in Nigeria, the Democratic Republic of Congo and Venezuela, and its stock was downgraded in April over separate legal woes in the DRC.