Michael Tillmann is out as CEO of Roche Diagnostics in Indianapolis, headquarters of the Swiss company's North American operations, a spokeswoman confirmed Monday.

The spokeswoman, Wendy Baker-Stein, did not provide a reason for Tillmann’s departure. She said his successor would be named “shortly.”

Tillmann had been in the job for 18 months following the resignation of Tiffany Olson in 2008. Olson is now working for Indianapolis-based Eli Lilly and Co.

Roche is one of the area’s 15 largest employers, sustaining 2,900 well-paying jobs at campuses in Indianapolis and Fishers. But it has cut jobs recently in its flagging insulin pump business and is in the midst of moving 300 jobs connected to its lab equipment business to Germany.

As IBJ reported last month, Roche has steadily lost market share in the diabetes market, which accounts for the biggest chunk of activity on the Indianapolis campus.

Those and other concerns had company insiders speculating that big changes would come once Daniel O’Day, a 22-year Roche veteran, became chief of the global diagnostics business Jan. 1. Tillmann’s exit appears to be one of his first moves.