COPENHAGEN, Dec 13 (Reuters) - Diabetes drug maker Novo Nordisk said on Monday it will invest 17 billion Danish crowns ($2.58 billion) into increasing production capacity in Denmark.

Novo, the world's biggest producer of diabetes drugs, said the investment will include three new manufacturing plants and expansion of one existing facility in Kalundborg, Denmark.

The facilities will mainly produce active pharmaceutical ingredients (API), the main biologically active components of medicines, as well as assembly and packaging of current and future oral and injectable drugs, it said.

The construction will according to plan be completed in 2027 and create around 400 new jobs on top of the 3,200 employed at Kalundborg, Novo said.

Novo has launched new, innovative GLP-1 drugs, used to treat diabetes and obesity, including a first-of-a-kind once-daily pill version of its semaglutide drug.

The investment at Kalundborg marks a doubling of the total investments made into its Danish plant over the last two decades.

Novo, which has nine production sites globally, in 2016 announced a $2 billion investment into a production plant in Clayton, North Carolina.

($1 = 6.5992 Danish crowns) (Reporting by Jacob Gronholt-Pedersen; editing by Jason Neely)