Treatment with protease inhibitors is associated with peripheral insulin resistance, leading to impaired or diabetic oral glucose tolerance in some of the patients, and with hyperlipidaemia. Overall, there is a large variation in the severity and clinical presentation of protease inhibitor-associated metabolic side-effects.

To define the extent and time course of HIV-proteinase inhibitor (PI) effects on serum lipid levels 148 patients on triple combination therapy including PIs and 91 patients on therapy with two nucleosides as a control group were evaluated. In the PI group there was a significant increase in total cholesterol after 3, 6 and 12 months compared to the baseline level (198, 204 and 203 vs. 176 mg/dl). The increase in triglycerides was 25.5% from the baseline at month 3. Indinavir had a significantly higher impact on cholesterol levels than saquinavir. No changes in lipids were seen in the control group. It was concluded that hyperlipidemia is associated with PI use, becomes evident within 3 months of treatment and seems to be substance specific.

These data indicate that increased triglycerides in HIV-infected patients with ART are primary due to reduced rates of VLDL transfer into denser lipoproteins implying a lower rate of lipoprotein lipase-mediated delipidation. In addition, total apo B synthesis was increased and shifted toward triglyceride-rich VLDL1. Overall, this lipoprotein profile in patients with ART-associated dyslipidemia implies an increased risk for cardiovascular events.

Antiretroviral therapy (ART) is frequently associated with metabolic alterations, including insulin resistance and diabetes mellitus. In this pilot study, we evaluated the effect of the PPARgamma activator troglitazone on ART-associated insulin resistance in HIV-infected patients with ART-associated diabetes mellitus. Six patients with protease inhibitor (PI)-associated diabetes mellitus, lipodystrophy and dyslipidemia were treated with troglitazone 400 mg q.d. for 3 months. Previous oral antidiabetics were discontinued prior to the study. At baseline and after 3 months, insulin sensitivity (intravenous insulin tolerance test), body composition (multifrequence bioelectrical impedance analysis) and fat distribution (CT scan quantification) were assessed. Glycaemic control (fasting and postprandial blood glucose, fructosamine, glycosylated haemoglobin) and serum lipid status were determined monthly. In four of the six patients, there was a clear improvement in insulin sensitivity, resulting in a reversal of insulin resistance in two of these patients. Overall, there was an increase in lean body mass and a decrease in total body fat. The volume of visceral adipose tissue decreased whilst the volume of subcutaneous adipose tissue increased. Total cholesterol, LDL and HDL cholesterol increased, and total triglycerides and VLDL-cholesterol decreased. No adverse effects such as hepatotoxicity were observed. Treatment with troglitazone 400 mg q.d. can ameliorate and in some cases even reverse ART-associated insulin resistance. Therefore, further studies including non-diabetic patients with ART-associated insulin resistance may be helpful in evaluating the long-term effects of thiazolidinediones on ART-associated insulin resistance and other metabolic complications, such as adipose maldistribution and dyslipidaemia.

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