Quantification of insulin-mediated glucose disposal in HIV-infected individuals: comparison of patients treated and untreated with protease inhibitors

Relative Effects of Insulin Resistance and Protease Inhibitor Treatment on Lipid and Lipoprotein Metabolism in HIV-Infected Patients

BACKGROUND

The relationship between insulin resistance, dyslipidemia, HIV infection, and antiretroviral therapy remains unclear, and the atherogenic nature of lipid and lipoprotein profiles in HIV-infected patients has not been fully characterized.

METHOD

We measured plasma lipid and lipoprotein subfractions using Vertical Auto Profile-II methodology and directly measured insulin-mediated glucose disposal in 45 protease inhibitor (PI)-treated and non-PI-treated HIV-infected patients.

RESULTS

PI-treated patients had higher total, LDL, and narrow-density LDL cholesterol (p <.05) and a trend toward higher triglycerides, whereas HDL cholesterol and LDL particle characteristics were unrelated to PI use or history of lipodystrophy. Insulin sensitivity did not differ on the basis of PI therapy, but decreased insulin sensitivity was associated with lower HDL and HDL-3 cholesterol (p <.01); elevated triglyceride (p <.01), VLDL 1+2, and VLDL 3a+3b lipoproteins (p <.01); and smaller, denser (more atherogenic) LDL particle characteristics (p <.01). Thus, the lipoprotein abnormality associated with PI use was increased LDL cholesterol, whereas changes in TG and HDL metabolism were associated with insulin resistance, independent of PI use.

CONCLUSION

The variables of PI-treatment, dyslipidemia, lipodsytrophy, and insulin resistance do not always cluster together in HIV-infected patients, which suggests that the metabolic phenotype emerging in treated patients results from a complex interplay of drug effects, immune restoration, and baseline insulin sensitivity.

Diabetes and HIV: current understanding and future perspectives

Diabetes mellitus is a chronic disease with a higher risk of associated infections. HIV infection severely affects diabetic patients and acts as a significant health concern. Highly active antiretroviral therapy (HAART) has changed HIV from an acute infection to a chronic infection with associated significant metabolic abnormalities such as insulin resistance, impaired glucose tolerance, metabolic syndrome, diabetes, dyslipidemia, obesity, and lipodystrophy. These metabolic disturbances add complexity to the standards of care in HIV infection and further increase the risk for cardiovascular disease and renal complications. The co-association of diabetes and HIV needs to be managed appropriately to prevent mortality and morbidity and improve patient outcome. The current understanding of diabetes and other metabolic abnormalities along with management strategies in HIV infected patients are summarized in this article. The review also focuses on recent challenges in the diagnosis and management of co-existent diabetes and HIV infection.

South Asian Consensus Guidelines for the rational management of diabetes in human immunodeficiency virus/acquired immunodeficiency syndrome

As newer methods of management are made available, and accessible, survival rates with human immunodeficiency virus (HIV) are increasing. This means that chronic, metabolic complications of HIV are becoming more frequent in clinical practice, as acute morbidity is controlled. Management of HIV/acquired immunodeficiency syndrome (AIDS) is gradually expanding to include these chronic and metabolic complications of the disease, and the adverse effects associated with its treatments, including diabetes. Unfortunately, no guidelines are available to help the medical practitioners choose appropriate therapy for patients with these conditions. The aim of the South Asian Consensus Guidelines is to provide evidence-based recommendations to assist healthcare providers in the rational management of type 2 diabetes mellitus in patients with HIV. The development of these guidelines used systematic reviews of available evidence to form its key recommendations. These guidelines and associated review of literature represent a compilation of available knowledge regarding rational management of diabetes in HIV. Patients of diabetes with concomitant HIV infection are managed optimally with insulin therapy and judicious use of highly active antiretroviral therapy with suitable alternatives is also recommended. These guidelines should prove helpful to physicians, not only in South Asia, but also across the globe, while managing patients with coexistent HIV and diabetes.

Effect of HCV infection on glucose metabolism in pregnant women with HIV receiving HAART

OBJECTIVE

A prospective study was designed to evaluate the prevalence and determinants of glucose metabolism abnormalities (GMAs) among HIV-1-infected pregnant women receiving highly active antiretroviral therapy (HAART).

METHODS

Blood samples were collected in fasting conditions and following a 100 g oral glucose tolerance test among HIV-infected pregnant women consecutively followed at asingle HIV reference centre in 2001-2008. GMAs were defined by glucose intolerance(IGT) or gestational diabetes (GDM), according to the National Diabetes Data Group criteria. Predictors of GMAs were assessed in univariate and multivariate analyses.

RESULTS

Overall, 78 women with no history of diabetes or GMAs were eligible for analysis. All were on stable HAART with either nevirapine or protease inhibitors (PIs) from at least 4 weeks at the time of sampling. GMAs during pregnancy were observed in 20 women (25.6%; GDM: 6, 7.7%; IGT: 14, 17.9%). In a multivariate analysis, after adjusting for age and ongoing antiretroviral treatment (PI or nevirapine), GMAs in pregnancy were significantly associated with HCV coinfection(adjusted odds ratio 4.16; 95% CI, 1.22-14.1;p = .022). No maternal or neonatalcomplications were observed.

CONCLUSION

GMAs represent a relevant issue in the management of HIV-1-infected pregnant women. Our data suggest that these abnormalities are relatively common in this particular group. Women with HCV coinfection have an increased risk of developing GMAs during pregnancy and should be monitored for potential complications.

Therapeutic effects of Nigella sativa on chronic HAART-induced hyperinsulinemia in rats

Prolonged use of highly active antiretroviral therapy (HAART) is associated with insulin resistance in HIV-1-positive patients. Small animal models that recapitulate the long-term effects of HAART may facilitate the identification of therapeutic agents to suppress these side effects. We investigated the protective effects of black seed oil (BSO) from Nigella sativa in Sprague-Dawley rats treated with a daily HAART regimen for 7 months. The antiretroviral drugs, consisting of nelfinavir (200 mg/kg), zidovudine (50 mg/kg), and efavirenz (20 mg/kg), were mixed with diet with or without BSO (400 microL/kg) supplementation. Significant increases in insulin and C-peptide levels were observed in HAART-treated groups, and concomitant BSO treatment reduced this hyperinsulinemia. Interestingly, HAART-treated rats showed reduced size of pancreatic islets that was not seen in BSO-exposed rats. In vitro studies showed that nelfinavir, alone and in combination with HAART, induced oxidative stress and decreased glucose-induced insulin production in INS-1 cells. Suppressed insulin production was restored in cells coexposed to either BSO or thymoquinone. Our findings demonstrated that chronic HAART may increase serum insulin levels by dysregulating both insulin production by beta cells and insulin action at the periphery. These deleterious effects may be prevented by dietary supplementation with BSO.

Whole body leucine flux in HIV-infected patients treated with or without protease inhibitors

The present study was carried out to assess the effects of protease inhibitor (PI) therapy on basal whole body protein metabolism and its response to acute amino acid-glucose infusion in 14 human immunodeficiency virus (HIV)-infected patients. Patients treated with PIs (PI+, 7 patients) or without PIs (PI-, 7 patients) were studied after an overnight fast during a 180-min basal period followed by a 140-min period of amino acid-glucose infusion. Protein metabolism was investigated by a primed constant infusion of l-[1-(13)C]leucine. Dual-energy X-ray absorptiometry for determination of fat-free mass (FFM) and body fat mass measured body composition. In the postabsorptive state, whole body leucine balance was 2.5 times (P < 0.05) less negative in the PI+ than in the PI- group. In HIV-infected patients treated with PIs, the oxidative leucine disposal during an acute amino acid-glucose infusion was lower (0.58 +/- 0.09 vs. 0.81 +/- 0.07 micromol x kg FFM(-1) x min(-1) using plasma [(13)C]leucine enrichment, P = 0.06; or 0.70 +/- 0.10 vs. 0.99 +/- 0.08 micromol x kg FFM(-1) x min(-1) using plasma [(13)C]ketoisocaproic acid enrichment, P = 0.04 in PI+ and PI- groups, respectively) than in patients treated without PIs. Consequently, whole body nonoxidative leucine disposal (an index of protein synthesis) and leucine balance (0.50 +/- 0.10 vs. 0.18 +/- 0.06 micromol x kg FFM x (-1) x min(-1) in PI+ and PI- groups respectively, P < 0.05) were significantly improved during amino acid-glucose infusion in patients treated with PIs. However, whereas the response of whole body protein anabolism to an amino acid-glucose infusion was increased in HIV-infected patients treated with PIs, any improvement in lean body mass was detected.

Metabolic Abnormalities Associated with the Use of Protease Inhibitors and Non-nucleoside Reverse Transcriptase Inhibitors

The use of protease inhibitors and non-nucleoside reverse transcriptase inhibitors for the treatment of HIV infection and AIDS has been associated with multiple abnormalities in glucose and lipid metabolism. Specifically, these abnormalities include insulin resistance, increased triglycerides and increased LDL cholesterol levels. The metabolic disturbances are due to a combination of factors, including the direct effect of medications, restoration to health and HIV disease, as well as individual genetic predisposition. Of the available anti-retroviral medications, indinavir has been associated with causing the most insulin resistance and ritonavir with causing the most hypertriglyceridemia.

Tolerability and safety of HIV protease inhibitors in adults

Antiretroviral drugs are associated with both short-term and long-term adverse events. Like other HIV drugs, protease inhibitors (PIs) may affect metabolic processes influencing body shape and body tissue composition, appearance, bone integrity, and cardiovascular status. However, numerous confounding variables including age, cigarette smoking, body mass index (BMI), duration of HIV infection, degree of immunodeficiency, concomitant antiretroviral agents, extent of previous treatment, and duration of treatment all blur the relationship between PI use and adverse events. Recent data suggest that the early PIs appear to have greater effects on such surrogate markers of disease risk as insulin resistance and cholesterol and triglyceride levels than the recently developed PIs. These data also suggest that evaluation of PIs as a class should be reconsidered and that it is probably not appropriate to extrapolate safety data obtained from individuals treated with first-generation agents in the era of potent combination antiretroviral therapy to those treated with recently developed PIs. Because PIs remain a critical component of successful antiretroviral therapy, evaluation of potential long-term complications with prolonged PI use is essential, as is delineation of the significant differences in safety profiles among individual PIs.

Oral Glucose Tolerance and Insulin Sensitivity Are Unaffected by HIV Infection or Antiretroviral Therapy in Overweight Women

OBJECTIVE

To assess the frequency of diabetes, prediabetes, and insulin resistance among a subset of participants in the Women's Interagency HIV Study (WIHS).

DESIGN

Cross-sectional substudy nested within a prospective multicenter cohort study. Women underwent 75 g oral glucose tolerance testing. Diagnoses of diabetes and prediabetes were made according to the American Diabetes Association criteria, and insulin resistance was determined by area under the curve insulin and homeostasis model assessment values.

SETTING

Six urban clinical sites in the United States (Brooklyn, NY; Bronx, NY; Washington, DC; Chicago, IL; San Francisco, CA; Los Angeles, CA) participate in the entire WIHS. The Bronx, NY, and San Francisco, CA, WIHS sites participated in this substudy.

PARTICIPANTS

A total of 258 women, 88 HIV negative, 74 HIV positive not on highly active antiretroviral therapy (HAART), and 96 HIV positive taking HAART were enrolled in the study.

MAIN OUTCOMES

Prevalence of diabetes, prediabetes, and insulin resistance was compared among the HIV-uninfected and HIV-infected women.

RESULTS

The frequency of diabetes, prediabetes, or insulin resistance was unrelated to HIV status or antiretroviral treatment. Increasing body mass index was the only characteristic associated with the combined endpoints of diabetes and prediabetes (odds ratio = 1.104, P = 0.0002).

CONCLUSIONS

Routine oral glucose tolerance testing of HIV-infected women is not supported by these findings. Elucidation of putative perturbations from HIV or antiretroviral medications requires direct studies of insulin resistance and beta-cell function.

Prevention and treatment of the metabolic syndrome

The prevalence of the metabolic syndrome is increasing owing to lifestyle changes leading to obesity. This syndrome is a complex association of several interrelated abnormalities that increase the risk for cardiovascular disease and progression to diabetes mellitus (DM). Insulin resistance is the key factor for the clustering of risk factors characterizing the metabolic syndrome. The National Cholesterol Education Program (NCEP) Adult Treatment Panel (ATP) III defined the criteria for the diagnosis of the metabolic syndrome and established the basic principles for its management. According to these guidelines, treatment involves the improvement of the underlying insulin resistance through lifestyle modification (eg, weight reduction and increased physical activity) and possibly by drugs. The coexistent risk factors (mainly dyslipidemia and hypertension) should also be addressed. Since the main goal of lipid-lowering treatment is to achieve the NCEP low-density lipoprotein cholesterol (LDL-C) target, statins are a good option. However, fibrates (as monotherapy or in combination with statins) are useful for the treatment of the metabolic syndrome that is commonly associated with hypertriglyceridemia and decreased high-density lipoprotein cholesterol (HDL-C) levels. The blood pressure target is < 140/90 mm Hg. The effect on carbohydrate homeostasis should possibly be taken into account in selecting an antihypertensive drug. Patients with the metabolic syndrome commonly have other less well-defined metabolic abnormalities (eg, hyperuricemia and raised C-reactive protein levels) that may also be associated with an increased cardiovascular risk. It seems appropriate to manage these abnormalities. Drugs that beneficially affect carbohydrate metabolism and delay or even prevent the onset of DM (eg, thiazolidinediones or acarbose) could be useful in patients with the metabolic syndrome. Furthermore, among the more speculative benefits of treatment are improved liver function in nonalcoholic fatty liver disease and a reduction in the risk of acute gout.