The secrecy surrounding HIV continues to be a major concern for older people living with HIV (OPWH) despite their long-term experience of HIV and the presence of other chronic diseases. Our study aims to highlight how the secrecy surrounding HIV can affect the management of the other conditions. The results of this socio-anthropological sub-study of the ANRS EP66 SEPTAVIH study, which assesses frailty in OPWH, are based on in-depth interviews conducted with 20 OPWH with multimorbidities aged 70 years and over and 9 caregivers. Based on a cross-sectional thematic analysis, this study shows that HIV infection differs from other chronic diseases due to the secrecy and stigma associated with HIV. These specific issues associated with HIV complicate the lives of OPWH, depriving them of support from loved ones and forcing them to exclude their general practitioner from their care system. This then causes OPWH with multiple chronic diseases to become socially vulnerable and isolated. Interventions that support the sharing of information on HIV among OPWH and also among caregivers need to be identified as a matter of urgency in order to improve the lives and management of OPWH with multimorbidities.