Germantown Police said a 70-year-old driver from Illinois has a diabetic reaction while driving, causing him to crash on I-41.
In a Facebook post, police said officers tried to pull the car over after it had been swerving across lanes on I-41, and even deployed tire deflation devices.
The car finally stopped on the Interstate near Main Street in Menomonee Falls.
The driver was sent to to the Community Memorial Hospital for treatment. He and been driving on an expired Illinois license and was issued a citation.
Police said additional action may be taken.
I-41 southbound was completely shut down near Pilgrim Road for parts of Monday evening.