Per the neat notarized certificate you can get from off the USUHS alumni web site:
"This is to certify that <insert rank, name, corps, branch of service>, served on active duty as a medical student officer (O-1, <USA, USN, USAF, USPHS>) at the Uniformed Services University of the Health Sciences (USU) from <matriculation date>(initial USU active duty date) to <graduation date>(USU graduation date. This period of active duty service is not creditable in determining eligibility for retirement or longevity for pay. [See § 2114(c) & § 2126, title10, U. S. Code.] It is, however, fully creditable active duty service in computing retired pay. [See § 2114(b)(1) of title 10, § 212 of title 42, and the attached OASD (FMP) memorandum dated 1 July 2002.]
With the above notarized certificate in hand, on my retirement DD214 in the remarks section, I had them include this statement: BLOCK 12 C DOES NOT INCLUDE ACTIVE DUTY SERVICE IN THE UNIFORMED SERVICES UNIVERSITY OF THE HEALTH SCIENCES (USUHS) YYYYMMDD (matriculation) - YYYYMMDD (graduation).
Hope this helps.