Effectiveness of Sitagliptin for HIV Insulin Resistance and Inflammation

People living with human immunodeficiency virus (HIV+) infection have a 2-fold greater prevalence and incidence of T2DM and cardiovascular disease (CVD) than the general population. The investigators lack safe and effective treatments for these HIV related cardiometabolic complications despite the fact that HIV infected adults represent an ideal clinical population in which to study interactions among chronic low-grade pro-inflammatory processes that are linked to the development of adipose accumulation, insulin resistance, ß-cell secretory failure, vascular endothelial dysfunction, atherosclerosis and CVD. Dipeptidyl peptidase-IV (DPP4)-inhibitors represent a new drug class that safely and effectively regulate glycemia in T2DM, but have not been adequately tested in HIV. Of note, pre-clinical studies suggest that DPP4-inhibitors have several pleiotropic actions that may specifically benefit people living with HIV infection. For example, DPP4 inhibition reduced adipose macrophage infiltration \& inflammation and increased the number of bone-derived endothelial progenitor cells in the circulation. Our preliminary findings indicate that DPP4 inhibition is virologically and immunologically safe in non-diabetic HIV+ adults taking combination antiretroviral therapy (in preparation), but the potential pleiotropic benefits have not been examined in HIV. The investigators propose a randomized, double blind, placebo controlled physiological study to test 2 potential pleiotropic benefits of DPP4 inhibition (100 mg sitagliptin/d, 8 wk): reduce circulating and adipose-specific markers of inflammation; and increase endothelial progenitor cell numbers used for vascular repair in 36 HIV+ adults with insulin resistance, central adiposity and CVD risk factors. The investigators hypothesize that sitagliptin will reduce circulating cytokine levels, reduce adipose tissue macrophage number and inflammation, and increase the number of circulating endothelial progenitor cells in HIV infected men and women. These physiological studies will advance our understanding about the efficacy of DPP4 inhibition in this high-risk group, and may help prevent the inexorable transition from insulin resistance to T2DM and CVD in HIV infected men and women.