Metformin Treatment and Immune Reconstitution in People With HIV and Type 2 Diabetes: A Matched Retrospective Study.

Background: Despite effective antiretroviral treatment (ART), HIV infection is associated with immune dysfunction and inflammation. Metformin has shown beneficial immunological and anti-inflammatory effects, including in people with HIV (PWH). We studied the potential association between metformin treatment and immune reconstitution in PWH. Methods: We conducted a retrospective cohort study set in Stockholm, Sweden. PWH with T2DM who initiated metformin treatment after at least 2 years on effective ART (exposed individuals) and metformin-naïve PWH (controls) were matched in a 1:1 ratio based on age, sex, baseline immune status, and duration of ART. Outcomes included mean values of CD4 cell counts and CD4/CD8 ratios from 1.5 years to 3.5 years after compared with 2 years before the exposed individual started metformin treatment (index date). Results: Among 1332 PWH, 43 metformin-exposed individuals (median age, 48 years; 11 years since start of ART) with T2DM and 43 nondiabetic controls (median age, 47 years; 11 years since start of ART) were included in the matched analyses. The median (interquartile range) change in CD4 T-cell count was 35 (-21 to 125) cells/μL among exposed individuals and 48 (-18 to 100) cells/μL among controls ( Conclusions: No significant differences in immune reconstitution were observed between metformin-treated individuals and matched controls over the 2-year follow-up period.