She won a silver medal at the 2002 Winter Olympics in the 4 × 7.5 km relay, while winning the gold medal at the Biathlon World Championships 2004 in Oberhof, 2004. Individually, she won the bronze medal at the 15 km of the Biathlon World Championship 2005 in Hochfilzen. Grubben won the last race of the 2005-06 Biathlon World Cup in Oslo, capturing the third position in the overall rankings. She accumulated eight World Cup victories in her career. At the World Championships taking place in Antholz-Anterselva, she collected bronze, silver and gold medals. The gold medal was secured by hitting 20 out of 20 possible targets.