Abstract 671 - Switching to Efavirenz from Protease Inhibitor-Based Therapy Does Not Improve Insulin Resistance after One Year in HIV Patients with Lipodystrophy Syndrome.

671 Switching to Efavirenz from Protease Inhibitor-Based Therapy Does Not Improve Insulin Resistance after One Year in HIV Patients with Lipodystrophy Syndrome.

V. Estrada*, N. G. P. De Villar, T. Martínez-Larrad, M. J. Téllez, and M. Serrano-Ríos.
Clín. de San Carlos, Madrid, Spain.

Background:High plasma insulin levels and insulin resistance (IR) are common disturbances in HIV patients with lipodystrophy syndrome (LDS), frequently observed after protease inhibitor (PI) treatment. It is not known if substitution of Efavirenz (EFV) for PI improves IR in the long term.

Methods:41 HIV patients with LDS-lipoatrophic phenotype were studied before and one year after substitution of EFV for PI without any change in nucleoside analogues (NA). Plasma insulin, proinsulin, glucose levels fasting and 1 and 2 hours after an oral 75-gr glucose tolerance test (OGTT), and insulin resistance index (IR) with HOMA-r were measured. HIV patients naive to therapy (n = 16) and healthy age-matched subjects (n = 368) were used as controls.

Results:82% of the patients were male, and mean age was 44.3. Total time on treatment (months): PI 21.7, AZT 28.9, d4T 17, 3TC 18, ddI 9.4. HIV-1 viral load was maintained at <50 copies/mL in all cases but one; CD4 increased from 498 to 582/mm³after one year. Weight, body mass index and waist-to-hip ratio didn't change during this period. Naive patients presented significantly lower fasting plasma insulin levels (mean [SD]) (10.8 [3.8]) than LDS patients before (13.2 [6.5]) and one year after switching (15.3 [8.6]) (mU/mL), p < 0.05 for both comparisons. 12.5% of naive HIV patients were in 75^thpercentile of fasting insulin levels in healthy controls (>15.38mU/mL) vs. 39% of LDS patients before switching and 30% at one year. Fasting proinsulin and post- OGTT insulin and proinsulin levels were similar between naive and LDS patients, and they didn't vary after one year. IR index was higher in LDS group than in control HIV-naive patients (3.25 [1.5] vs. 2.4 [0.86], p < 0.01). IR index didn't change after one year of substitution (3.25 [1.5] vs. 3.89 [2.4], p = NS).

Conclusions:In HIV patients with predominant loss of fat, plasma insulin levels and insulin resistance index do not modify one year after switching from PI to EFV. These results suggest that in lipodystrophy syndrome, other factors unrelated to PI usage may induce insulin resistance.