Production of its top earner, copper, was down nine per cent due to lower grades at two South American mines.
Copper output was 350,700 tonnes in the first quarter, below most analysts’ forecasts.
The fall was due to lower grades at the Alumbrera mine in Argentina and the Antamina mine in Peru, and to a maintenance shutdown at Collahuasi, in Chile.
Glencore has a bigger exposure to base metals than iron ore compared with its large rivals, with a large commodity trading division in addition to its mining and oil assets.
Bernstein analyst Paul Gait said the production figures were “disappointing”, noting that base metals and coal failed to meet expectations.
Meanwhile, coal production rose four per cent in the first quarter to 35.6m tonnes, thanks to the commissioning of two new thermal coal projects in South Africa.
However, a potential output cut at Glencore’s Optimum coal operation in South Africa is expected to have an impact later in 2015, the company said.
Glencore, which is led by Ivan Glasenberg, was knocked back by rival mining firm Rio Tinto last summer, after making an offer to take over its larger competitor.