Do the 2018 Cigna exchange plans in Illinois have the lowest rates?

In most cases, yes.

The Illinois Department of Insurance confirmed in mid-September that Cigna would offer on-exchange plans in the exchange, in the Chicago area including Cook, Dupage, Will, and Kane Counties.

A quick check of a few Cook County zip codes using our quoting tool shows that Cigna is offering some of the least-expensive plans in the Chicago area for 2018 by about 10-15%. The network availability is limited but ample if you are flexible on picking a doctor.