Sexual Identity and Condomless Sex Among Mexican MSM: The Overlooked Role of Heterosexual-Identified MSM

HIV prevention efforts in Mexico often overlook heterosexual-identified men who have sex with men (H-MSM), a subgroup at elevated risk for HIV. Using data from the 2021–2022 National Survey on Sexual and Gender Diversity (ENDISEG), we examined condomless sex among cisgender MSM, categorizing participants by sexual identity (heterosexual vs. gay, bisexual, or other non-heterosexual), sexual behavior (only male partners vs. both male and female), and their combinations: H-MSM, H-MSMW, GB+MSM, and GB+MSMW. Among cisgender men, 3.9% (n = 775) reported a male sexual partner in the past year, and 41% of them identified as heterosexual. Condomless sex was reported by 63.8% of MSM overall and was most common among H-MSM (74.4%). Probit regression analysis showed significantly lower probabilities of condomless sex among H-MSMW (−19.8%), GB+MSM (−14.8%), and GB+MSMW (−15.9%) compared to H-MSM. Additional risk factors included older age, lower education, and depression. These findings underscore the limitations of considering MSM as one group and reveal a sizable, high-risk subgroup that may be missed by current HIV programs. Effective prevention strategies must integrate sexual identity and behavior and be adapted to Mexico’s sociocultural context. Identity-sensitive approaches, particularly for H-MSM and H-MSMW, are essential to reduce HIV transmission in this population.