To determine that a man has AIDS, the diagnosis is based on medical history, symptoms, and laboratory tests. 1. Medical history: AIDS is caused by human immunodeficiency virus (HIV) infection, which can be transmitted through blood, mother-to-child, and sex. If there is a history of unclean sex, homosexual sex, long-term drug abuse, etc., combined with the clinical manifestations, AIDS is highly suspected. 2. Symptoms: Low fever, diarrhea, sore throat, fatigue, skin rash, etc. will appear in the acute infection period of AIDS, which will subside within one month, but the above symptoms are not specific and cannot be used as the basis of diagnosis. 3. Laboratory tests: HIV antibody, HIV nucleic acid, CD4+ T-cells, etc. can be tested in regular medical institutions to confirm the diagnosis, and laboratory tests are the basis for the diagnosis of AIDS. If you feel uncomfortable after high-risk behavior, it is recommended that you go to a regular hospital in time and under the guidance of a doctor for examination to make a clear diagnosis.