The increasing burden of non-communicable diseases, such as hypertension, diabetes and dyslipidaemia, presents key challenges to achieving optimal HIV care outcomes among ageing people living with HIV. These diseases are often comorbid and are exacerbated by psychosocial and structural inequities. This interaction among multiple health conditions and social factors is referred to as a syndemic. In the USA, there are substantial disparities by social position (ie, racial, ethnic and socioeconomic status) in the prevalence and/or control of non-communicable diseases and HIV. Intersecting stigmas, such as racism, classism and homophobia, may drive these health disparities by contributing to healthcare avoidance and by contributing to a psychosocial syndemic (stress, depression, violence victimisation and substance use), reducing success along the HIV and non-communicable disease continua of care. Our hypothesis is that marginalised populations experience disparities in non-communicable disease incidence, prevalence and control, mediated by intersectional stigma and the psychosocial syndemic.Collecting data over a 4 year period, we will recruit sexual minority men (planned n=1800) enrolled in the MACS/WIHS Combined Cohort Study, a long-standing mixed-serostatus observational cohort in the USA, to investigate the following specific aims: (1) assess relationships between social position, intersectional stigma and the psychosocial syndemic among middle-aged and ageing sexual minority men, (2) assess relationships between social position and non-communicable disease incidence and prevalence and (3) assess relationships between social position and HIV and non-communicable disease continua of care outcomes, mediated by intersectional stigma and the psychosocial syndemic. Analyses will be conducted using generalised structural equation models using a cross-lagged panel model design.This protocol is approved as a single-IRB study (Advarra Institutional Review Board: Protocol 00068335). We will disseminate results via peer-reviewed academic journals, scientific conferences, a dedicated website, site community advisory boards and forums hosted at participating sites.