This randomized, controlled study showed that Medicaid coverage generated no significant improvements in measured physical health outcomes in the first 2 years, but it did increase use of health care services, raise rates of diabetes detection and management, lower rates of depression, and reduce financial strain.

FORBES: Oregon Health Experiment Shows That Having Health Insurance Is Different Than Being Healthy

The Lewin study also "found evidence of lower emergency room utilization and improved access to physician services" from "care management programs" for Medicaid patients with asthma, diabetes, heart problems and mental health disorders.

WSJ: Review & Outlook: Providential Design