This study will investigate changes in insulin sensitivity, lipid metabolism and endocrine profile in HIV-negative subjects exposed to Biktarvy (B/F/TAF) compared to subject not exposed to B/F/TAF for 28 days.

A randomised, crossover study investigating the difference in changes in insulin sensitivity (determined by peripheral glucose uptake using a euglycaemic clamp) with the administration of Biktarvy (B/F/TAF) compared to no B/F/TAF for 28 days in HIV seronegative healthy volunteers. Group 1: B/F/TAF tablet once daily for the first 28 days of the study. No treatment for the last 44 days of the study. Group 2: No treatment for the first 28 days of the study. B/F/TAF tablet once daily for the last 28 days of the study (day 44-72). Research bloods, endocrine profiles, weight and urine samples will be collected at baseline, as well as day 28, 44, and 72 to enable comparative analyses. Participants will be closely monitored whilst taking the study medications. Participants will exit the study 72 days post-randomisation, with a follow-up call 28 days after exiting.