Can a commander request medical results from providers?
(From a PDF info paper that's in the second link).
https://www.health.mil/Military-Health-Topics/Privacy-and-Civil-Liberties/HIPAA-Compliance-within-the-MHS/Military-Command-Exception
The Health Insurance Portability and Accountability Act (HIPAA) permits protected health information (PHI) of Armed Forces personnel to be disclosed under special circumstances. Commonly referred to as the Military Command Exception, covered entities such as military treatment facilities may disclose the PHI of Armed Forces personnel to Command authorities for authorized activities.
These activities include fitness for duty determinations, fitness to perform a particular assignment, or other activities necessary for the military mission. PHI disclosed to military command authorities, while no longer subject to HIPAA, remains protected under the Privacy Act of 1974.
https://www.army.mil/article/46296/release_of_protected_health_information_to_commanders
It seems a little grey area since commanders can request PHI to determine readiness...but not sure about the direct access to medical records. You may want to see about talking to patient advocacy at the hospital. Perhaps JAG? It's a bit iffy the commander got the results before you did.
Learn more about the Military Command Exception; specifically, as it relates to the HIPAA Privacy Rule and applicable DoD issuances in that a DoD covered entity (CE) may use or disclose the protected health information (PHI) of Armed Forces members for activities deemed “necessary by appropriate military command authorities to assure the proper execution of the military mission.”
Learn more about the Military Command Exception; specifically, as it relates to the HIPAA Privacy Rule and applicable DoD issuances in that a DoD covered entity (CE) may use or disclose the protected health information (PHI) of Armed Forces members for activities deemed “necessary by appropriate military command authorities to assure the proper execution of the military mission.”