Highly active antiretroviral therapy dysregulates proliferation and differentiation of human pre-adipocytes.

AIM: To investigate the mechanism(s) by which potential effects of multi-drug highly-active antiretroviral therapy contributes to lipodystrophy syndrome. METHODS: Preadipocytes from healthy donors were assessed for proliferation and differentiation in the presence of nucleoside reverse transcriptase inhibitors (NRTIs), nonnucleoside reverse transcriptase inhibitors (NNRTIs), and protease inhibitors (PIs) individually and in combination. Effects on proliferation were assessed with a 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide assay and effects on differentiation were assessed from glycerol-3-phosphate dehydrogenase (GP DH) activity and quantitation of Oil Red O staining for intracellular lipid. Data were analyzed with a randomized block ANOVA with post-hoc Fisher's Least Significant Difference test. RESULTS: Preadipocyte proliferation was inhibited by a combination of NNRTI + NRTI (14% at 48 h, P < 0.001) and PI + NRTI (19% at 48 h, P < 0.001) with additional suppression when ritonavir (RTV) was added (26% at 48 h). The drug combination of atazanavir (ATV) + RTV + emtricitabine (FTC) + tenofovir (TDF) had the greatest inhibitory effect on proliferation at 48 h. Preadipocyte differentiation was most significantly reduced by the efavirenz + FTC + TDF assessed either by GPDH activity (64%) or lipid accumulation (39%), P < 0.001. Combining NRTIs with a PI (ATV + FTC + TDF) significantly suppressed differentiation (GPDH activity reduced 29%, lipid accumulation reduced by 19%, P < 0.01). This effect was slightly greater when a boosting amount of RTV was added (ATV + FTC + TDF + RTV, P < 0.001). CONCLUSION: Although combination antiretroviral therapy is clinically more efficacious than single drug regimens, it also has a much greater inhibitory effect on preadipocyte proliferation and differentiation.

Changes in diabetes medications in the Diabetes and Periodontal Therapy Trial and their effect on hemoglobin A1c (HbA1c).

OBJECTIVE: Evaluate the effect of medications and medication changes during the Diabetes and Periodontal Therapy Trial (DPTT) on the primary study outcome, namely, change in hemoglobin A1c (HbA1c) at 6months following baseline. METHODS: The DPTT set strict criteria for changes in diabetes medications. Medication change was defined as: change in dose of any 1 oral hypoglycemic agent by more than two-fold, change in dose of insulin of >10% and/or addition or subtraction of an oral hypoglycemic agent, insulin or non-insulin injectable agents. Comparisons between the treatment (non- surgical periodontal therapy) and control (no therapy) groups used t-tests for continuous variables and chi-square tests for categorical variables, including DPTT defined diabetes medication changes between baseline (BL) and 3month visits and 3- and 6-month visits. Changes in HbA1c were compared across the four medication change categories using ANOVA models, overall and for each treatment group separately. RESULTS: Baseline medication use was similar between the treatment groups (p>0.40), as were medication changes between BL- 3month visits and 3 and 6month visits (p=0.58). Participants with higher BL HbA1c (>8%) and those taking insulin at BL were more likely to have a change in medication (p=0.03). CONCLUSIONS: The DPTT had the most rigorous definition of medication changes and medication monitoring of any trial in this field to date. The absence of a significant difference in medication changes between treatment groups may suggest that such changes did not play a role in the negative outcome of the DPTT.

The effect of nonsurgical periodontal therapy on hemoglobin A1c levels in persons with type 2 diabetes and chronic periodontitis: a randomized clinical trial.

IMPORTANCE: Chronic periodontitis, a destructive inflammatory disorder of the supporting structures of the teeth, is prevalent in patients with diabetes. Limited evidence suggests that periodontal therapy may improve glycemic control. OBJECTIVE: To determine if nonsurgical periodontal treatment reduces levels of glycated hemoglobin (HbA1c) in persons with type 2 diabetes and moderate to advanced chronic periodontitis. DESIGN, SETTING, AND PARTICIPANTS: The Diabetes and Periodontal Therapy Trial (DPTT), a 6-month, single-masked, multicenter, randomized clinical trial. Participants had type 2 diabetes, were taking stable doses of medications, had HbA1c levels between 7% and less than 9%, and untreated chronic periodontitis. Five hundred fourteen participants were enrolled between November 2009 and March 2012 from diabetes and dental clinics and communities affiliated with 5 academic medical centers. INTERVENTIONS: The treatment group (n = 257) received scaling and root planing plus chlorhexidine oral rinse at baseline and supportive periodontal therapy at 3 and 6 months. The control group (n = 257) received no treatment for 6 months. MAIN OUTCOMES AND MEASURES: Difference in change in HbA1c level from baseline between groups at 6 months. Secondary outcomes included changes in probing pocket depths, clinical attachment loss, bleeding on probing, gingival index, fasting glucose level, and Homeostasis Model Assessment (HOMA2) score. RESULTS: Enrollment was stopped early because of futility. At 6 months, mean HbA1c levels in the periodontal therapy group increased 0.17% (SD, 1.0), compared with 0.11% (SD, 1.0) in the control group, with no significant difference between groups based on a linear regression model adjusting for clinical site (mean difference, -0.05% [95% CI, -0.23% to 0.12%]; P = .55). Periodontal measures improved in the treatment group compared with the control group at 6 months, with adjusted between-group differences of 0.28 mm (95% CI, 0.18 to 0.37) for probing depth, 0.25 mm (95% CI, 0.14 to 0.36) for clinical attachment loss, 13.1% (95% CI, 8.1% to 18.1%) for bleeding on probing, and 0.27 (95% CI, 0.17 to 0.37) for gingival index (P < .001 for all). CONCLUSIONS AND RELEVANCE: Nonsurgical periodontal therapy did not improve glycemic control in patients with type 2 diabetes and moderate to advanced chronic periodontitis. These findings do not support the use of nonsurgical periodontal treatment in patients with diabetes for the purpose of lowering levels of HbA1c. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00997178.

Peripheral fat loss and decline in adipogenesis in older humans.

OBJECTIVE: Aging is associated with a redistribution of body fat including a relative loss of subcutaneous peripheral fat. These changes in body fat can have important clinical consequences since they are linked to increased risk of metabolic complications. The causes and mechanisms of loss of peripheral fat associated with aging are not clear. The aim of this study was to assess whether defects in adipogenesis contribute to fat loss in aging humans, as suggested from animal studies, and to evaluate the role of inflammation on pathogenesis of fat loss. MATERIALS/METHODS: Preadipocytes isolated from subcutaneous peripheral fat of healthy young and elderly subjects were compared in their ability to replicate and differentiate. RESULTS: The results show that both the rate of replication and differentiation of preadipocytes are reduced in older subjects. The reduction in adipogenesis is accompanied by a higher plasma level of the inflammatory marker, soluble tumor necrosis factor receptor 2, and greater release of tumor necrosis factor α from fat tissue. CONCLUSIONS: Thus, the gradual relative loss of peripheral fat in aging humans may in part result from a defect in adipogenesis, which may be linked to inflammation and increased release of proinflammatory cytokines from fat tissue.

Rosiglitazone-Mediated Effects on Skeletal Muscle Gene Expression Correlate with Improvements in Insulin Sensitivity in Individuals with HIV-Insulin Resistance.

Rosiglitazone, an agonist of peroxisome proliferator activated receptor (PPARγ), improves insulin sensitivity by increasing insulin-stimulated glucose uptake into muscle tissue. This study was undertaken to assess changes in expression of PPAR-regulated genes in muscle tissue following treatment of HIV-associated insulin resistance with rosiglitazone. Muscle gene expression was assessed in twenty-two seronegative HIV subjects (control), 21 HIV-infected individuals with normal insulin sensitivity (HIV-IS) and 19 HIV-infected individuals with insulin resistance (HIV-IR). A subset of the HIV-IR group (N = 10) were re-evaluated 12 weeks after treatment with 8 mg/d of rosiglitazone. The HIV-IR group's rosiglitazone-mediated improvement in insulin sensitivity was highly correlated with increased expression of PPARγ and carnitine palmitoyl transferase-1 (CPT-1), (r = 0.87, P < .001) and (r = 0.95, P < .001), respectively. The changes in PPARγ expression were also correlated with the changes in CPT1 expression (r = 0.75, P = .009). The results suggest that rosiglitazone; may have a direct effect on muscle tissue to improve insulin sensitivity.

Effect of ritonavir and atazanavir on human subcutaneous preadipocyte proliferation and differentiation.

Protease inhibitors (PIs) have been implicated in the development of HIV-associated lipodystrophy through a reduction in the differentiation of preadipocytes. While atazanavir (ATV) is associated with fewer clinical metabolic abnormalities in the short-term, the effects of long-term exposure are not known. ATV effects on preadipocyte replication or differentiation would indicate the potential for long-term problems. This study compared ritonavir (RTV) and ATV effects on preadipocyte replication and differentiation in human primary cultures. Preadipocytes from subcutaneous fat were studied in the presence of therapeutic concentrations of RTV and ATV for replication, differentiation, and adipokine secretion. The effects of the drugs on the expression of PPARgamma and related genes during differentiation were also assessed by real-time quantitative PCR. RTV induced a significant inhibition of preadipocyte proliferation, differentiation and adiponectin secretion. ATV at concentrations within the range of therapeutic levels did not affect differentiation or adiponectin secretion, but did have inhibitory effects on preadipocyte proliferation. Inhibition of differentiation by PIs was associated with decreased expression of PPARgamma, C/EBPalpha, and aP2 genes. In summary, although ATV at therapeutic levels has a smaller impact on adipogenesis, alterations in preadipocyte proliferation suggest the potential for adverse effects with long-term use.

Feeding acutely stimulates fibrinogen synthesis in healthy young and elderly adults.

Fibrinogen is a positive acute-phase protein and its hepatic synthesis is enhanced following inflammation and injury. However, it is not clear whether fibrinogen synthesis is also responsive to oral nutrients and whether the response to a meal may be affected by age. Our aim in this study was to investigate the acute effect of oral feeding on fibrinogen synthesis in both young and elderly men and women. Fibrinogen synthesis was determined in 3 separate occasions from the incorporation of l[(2)H(5)]phenylalanine (43 mg/kg body weight) in 8 young (21-35 y) and 8 elderly (>60 y) participants following the ingestion of water (control), a complete liquid meal (15% protein, 30% fat, and 55% carbohydrate), or only the protein component of the meal. The ingestion of the complete meal enhanced fibrinogen fractional synthesis rates (FSR) by 17 +/- 6% in the young and by 38 +/- 10% in the elderly participants compared with the water meal (P < 0.02). A comparable stimulation of FSR occurred with only the protein component of the meal in both young (29 +/- 7%) and elderly participants (41 +/- 9%) compared with the water meal (P < 0.005). Similar results were obtained when fibrinogen synthesis was expressed as absolute synthesis rates (i.e. mg.kg(-1).d(-1)). The results demonstrate that fibrinogen synthesis is acutely stimulated after ingestion of a meal and that this effect can be reproduced by the protein component of the meal alone, both in young and elderly adults.

Importance of the high-molecular-mass isoform of adiponectin in improved insulin sensitivity with rosiglitazone treatment in HIV disease.

The present study was designed to investigate the relationship of isoforms of adiponectin to insulin sensitivity in subjects with HIV-associated insulin resistance in response to treatment with the thiazolidinedione, rosiglitazone. The two isoforms of adiponectin, HMW (high-molecular-mass) and LMW (low-molecular-mass), were separated by sucrose-gradient-density centrifugation. The amount of adiponectin in gradient fractions was determined by ELISA. Peripheral insulin sensitivity (Rd) was determined with hyperinsulinaemic-euglycaemic clamp, whereas hepatic sensitivity [HOMA (Homoeostasis Model Assessment) %S] was based on basal glucose and insulin values. Treatment with rosiglitazone for 3 months resulted in a significant improvement in the index of hepatic insulin sensitivity (86.4+/-15% compared with 139+/-23; P=0.007) as well as peripheral insulin sensitivity (4.04+/-0.23 compared with 6.17+/-0.66 mg of glucose/kg of lean body mass per min; P<0.001). Improvement in HOMA was associated with increased levels of HMW adiponectin (r=0.541, P=0.045), but not LMW adiponectin. The present study suggests that the HMW isoform of adiponectin is important in the regulation of rosiglitazone-mediated improvement in insulin sensitivity in individuals with HIV-associated insulin resistance, particularly in the liver.

Influence of age on the association of retinol-binding protein 4 with metabolic syndrome.

OBJECTIVE: The relationships of retinol-binding protein 4 (RBP4) with insulin sensitivity and body fat distribution have been investigated in a few recent studies with conflicting results. This may have been due to differences in ages of the subjects in the different studies. The aim of this study was to investigate whether the association of RBP4 and insulin sensitivity and percent trunk fat are influenced by age. METHODS AND PROCEDURES: Cross-sectional analyses of 48 young subjects and 55 elderly subjects. Insulin sensitivity was determined by a hyperinsulinemic-euglycemic clamp. Body fat distribution was determined by a dual-energy X-ray absorptiometry (DXA). RESULTS: In the young subjects, RBP4 levels were associated with insulin sensitivity (r = -0.30, P = 0.04), percent trunk fat (r = 0.54, P < 0.001), triglycerides (r = 0.44, P = 0.003), low-density lipoprotein (r = 0.38, P = 0.01). In contrast, in the elderly subjects there was no correlation between RBP4 levels and insulin sensitivity (r = -0.18, P = 0.20), percent trunk fat (r = 0.00, P = 0.10), triglycerides (r = 0.25, P = 0.10), and low-density lipoprotein (r = -0.11, P = 0.47). DISCUSSION: The associations of RBP4 with insulin sensitivity, percent trunk fat, and lipid levels are influenced by age.

Endothelial adhesion molecules are associated with inflammation in subjects with HIV disease.

BACKGROUND: The presence of the adhesion molecules intercellular adhesion molecule-1 (ICAM-1) and soluble vascular cell adhesion molecule-1 (VCAM-1) is associated with elevated risk of cardiovascular disease. Subjects with human immunodeficiency virus (HIV) disease have multiple risk factors for cardiovascular disease, including elevated serum lipid levels, insulin resistance, and elevated levels of ICAM-1 and VCAM-1. This study assessed the variables associated with elevated adhesion molecule levels in this patient population. METHODS: Serum levels of ICAM-1 and VCAM-1 were assessed in 31 subjects without HIV disease and 52 subjects with HIV disease. Pearson correlation indicated a significant relationship between ICAM concentration and other variables, including CD4+ cell count, HIV viral burden, insulin sensitivity, and serum lipid level. Multiple regression modeling was used to determine the strengths of association among the variables. RESULTS: Subjects with HIV disease had elevated levels of ICAM-1 and VCAM-1. Pearson correlation analysis revealed significant associations between ICAM-1 and VCAM-1 level and insulin sensitivity, plasma lipid level, and presence of type 2 soluble receptor for tumor necrosis factor-alpha (sTNFR2). With multiple regression modeling to control for interdependence, only sTNFR2, a marker of inflammation, was an independent predictor of ICAM-1 and VCAM-1 levels. CONCLUSIONS: The study suggests that many of the variables associated with ICAM-1 and VCAM-1 levels can be related to their impact on inflammation.

Limb fat to trunk fat ratio in elderly persons is a strong determinant of insulin resistance and adiponectin levels.

BACKGROUND: Similar to lipodystrophy syndromes, aging results in increased visceral adiposity with loss of subcutaneous adipose tissue in the extremities. The hypothesis of this study is that the distribution of limb fat to trunk fat (LF/TF) ratio in elderly persons has a stronger correlation than trunk fat alone to insulin resistance and adiponectin levels. METHODS: Thirty-eight elderly participants were divided into an insulin-resistant (IR) group and an insulin-sensitive (IS) group. Limb fat and trunk fat were measured by dual-energy x-ray absorptiometry. Insulin resistance was measured by a hyperinsulinemic-euglycemic clamp. RESULTS: There was no significant difference between the IS and IR groups with respect to body mass index, body fat index, absolute amount of trunk fat, or percent body fat. However, the difference in LF/TF ratio between the IS (1.02 +/- 0.05) and the IR groups (0.77 +/- 0.05) was highly significantly different (p <.001). Insulin resistance had a stronger correlation to the LF/TF ratio (r = 0.61, p <.001) than to absolute trunk fat (r = -0.32, p =.051). Adiponectin levels had a strong association with the LF/TF ratio (r = 0.63, p <.001), but did not correlate to absolute trunk fat (r = -0.24, p =.18). CONCLUSIONS: The distribution of body fat (LF/TF ratio) in elderly persons is a stronger determinant of insulin resistance and adiponectin levels than is trunk fat alone. The LF/TF ratio can be a useful tool to assess insulin sensitivity in the elderly population.

Wall suction applied to needle muscle biopsy - a novel technique for increasing sample size.

BACKGROUND: The needle biopsy technique described by Bergström is the most commonly used technique to obtain samples to assess muscle metabolism. Sampling of muscle, particularly the vastus lateralis, has become an essential tool in biomedical and clinical research. Optimal sample size is critical for availability of tissue for processing. To evaluate the effectiveness of a novel technique to obtain adequate sample size using wall suction applied to needle muscle biopsy, we collected samples from subjects in on-going clinical studies for gene expression. MATERIALS AND METHODS: Muscle biopsy samples of the vastus lateralis using 6 mm Bergström needles under local anesthesia were obtained from 55 subjects who had volunteered to participate in this research project. The vastus lateralis was biopsied according to the methods described by Bergström with a 6 mm biopsy needle. Wall suction was applied to the inner bore of the biopsy needle after the needle was inserted into the muscle. RESULTS: The mean sample of biopsy taken using the 6 mm was 233 mg (n = 55). The wall suction (200 mm Hg) applied to the needle pulled the surrounding tissue into the central bore of the needle. The quality of the samples was adequate for all biochemical assays. The biopsy technique did not result in any complications due to infection or bleeding. CONCLUSIONS: Using a novel technique of connecting a 6 mm Bergström biopsy needle to wall suction, we have obtained 200 to 300 mg muscle biopsy specimens uniformly, with ease, and minimal discomfort. An increase in sample size allows for a wider variety of biochemical and histopathological analysis.

Response of albumin synthesis to oral nutrients in young and elderly subjects.

BACKGROUND: The synthesis of albumin after oral ingestion of nutrients provides a means of storing amino acids, which can be made available during periods of fasting. OBJECTIVE: This study was undertaken to see whether the response of albumin synthesis to the oral intake of nutrients is compromised in elderly subjects. DESIGN: Albumin synthesis was determined from the incorporation of 43 mg l-[(2)H(5)]phenylalanine/kg body wt. Eight elderly subjects (aged >60 y) and 8 young subjects (aged 21-35 y) were studied on 3 separate occasions: after the intake of water, a liquid meal (with 15% of energy from protein, 30% of energy from fat, and 55% of energy from carbohydrate), or an isonitrogenous but not isocaloric meal containing only protein. RESULTS: Mean (+/-SEM) albumin synthesis, expressed as an absolute rate (ie, the amount of albumin synthesized per day), was significantly lower in elderly subjects (108 +/- 7 mg . kg body wt(-1) . d(-1)) than in young subjects (141 +/- 7 mg . kg body wt(-1) . d(-1)). In response to the complete meal, albumin synthesis was significantly increased in both the elderly (144 +/- 7 mgkg body wt(-1) . d(-1)) and the young (187 +/- 11 mg . kg body wt(-1) . d(-1)) subjects. The protein component of the meal was sufficient to stimulate albumin synthesis in both the elderly (147 +/- 14 mg . kg body wt(-1) . d(-1)) and the young (182 +/- 6 mg . kg body wt(-1) . d(-1)) subjects. CONCLUSIONS: Elderly subjects have lower rates of albumin synthesis than do young subjects during fasting, but they stimulate albumin synthesis proportionately in response to the oral ingestion of protein. The intakes of additional fat and carbohydrate do not stimulate albumin synthesis further.

Retinol-binding protein 4 is associated with insulin resistance and body fat distribution in nonobese subjects without type 2 diabetes.

BACKGROUND: Adipose tissue is responsible for releasing various adipokines that have been related to insulin resistance. Understanding the relationship of these adipokines to insulin resistance may foster the development of new treatments for diabetes. OBJECTIVES: The primary objective of this study was to determine whether an association between retinol-binding protein 4 (RBP4) and insulin resistance exists in nonobese individuals without a family history or diagnosis of diabetes. The secondary objective was to determine by a dual energy x-ray absorptiometry scan which adipose tissue depot most closely relates to RBP4 levels. DESIGN: Cross-sectional analysis of 92 study participants ranging in age from 20 to 83 yr was performed. The range of body mass index (BMI) was from 18 to 30 kg/m(2). Exclusion criteria were a BMI greater than 30 kg/m(2), family history of diabetes, or a diagnosis of diabetes. Insulin sensitivity was determined by a hyperinsulinemic euglycemic clamp. Body fat was measured by dual energy x-ray absorptiometry scan. RESULTS: RBP4 values were lower in females (35.8 +/- 1.7 microg/ml) compared with males (39.9 +/- 1.4 microg/ml; P = 0.06). RBP4 levels were found to correlate negatively with insulin sensitivity (r = -0.32; P = 0.002) and positively with age (r = 0.38; P < 0.001). RBP4 levels did not correlate with BMI (r = -0.13; P = 0.22), trunk fat (r = 0.16; P = 0.22), or percent body fat (r = 0.07; P = 0.65). However, RBP4 levels did correlate with percent trunk fat (r = 0.36; P = 0.001). CONCLUSION: These findings indicate a relationship between RBP4, insulin sensitivity, and percent trunk fat in individuals who may not have features of insulin resistance.

The increase in human muscle protein synthesis induced by food intake is similar when assessed with the constant infusion and flooding techniques.

Food intake is accompanied by a stimulation of muscle protein synthesis. However, the reported magnitude of the response differs with different methods of measurement. The aim of this study was to assess whether the response to feeding is dependent on the technique used for measurement when length and amount of feeding are controlled. Muscle protein fractional synthesis rates (FSRs) were measured both in the fasting and feeding states in 2 groups of healthy volunteers (n = 8). Two techniques were used to measure FSR: in one group, FSRs were assessed with a primed constant infusion of L-[2H5]phenylalanine, whereas in the other, a flooding amount of the same label was employed. The fasting FSRs assessed with the constant infusion method and estimated using the free amino acid in the tissue fluid to represent the precursor pool for protein synthesis were comparable to those obtained with the flooding method (1.94 +/- 0.15 vs. 1.86 +/- 0.13%/d). The degree of stimulation due to feeding (P < 0.02) did not differ between the constant infusion (+15%) and flooding (+22%) techniques. The stimulatory effect of feeding on muscle FSR was associated with enhanced phosphorylation of the Mr = 70,000 ribosomal protein S6 kinase, suggesting that it may involve activation of translation. This study demonstrates that human muscle FSRs obtained with the constant infusion technique are comparable to those obtained with the flooding method and that, in response to feeding, the 2 techniques give comparable estimates of stimulation.

Insulin and carbohydrate dysregulation.

Patients with human immunodeficiency virus receiving highly active antiretroviral therapy (HAART) may experience abnormal body composition changes as well as metabolic abnormalities, including dyslipidemia, increases in triglycerides, low high-density lipoprotein cholesterol levels, and abnormal carbohydrate metabolism, ranging from insulin resistance with and without glucose intolerance to frank diabetes. Whether the body composition changes (i.e., increased visceral adiposity and fat wasting in the peripheral tissues) are linked to abnormalities in carbohydrate metabolism is unclear. The use of HAART with and without therapy with protease inhibitors (PIs) is related to carbohydrate abnormalities and changes in body composition. Regimens that include PIs appear to have a higher incidence of insulin resistance (up to 90%) and diabetes mellitus (up to 40%). The etiology of these abnormalities is not well understood; what is known about insulin and carbohydrate dysregulation with HAART is discussed.

Adiponectin and leptin levels in HIV-infected subjects with insulin resistance and body fat redistribution.

In this study, we sought to determine the relationship between serum levels of leptin and adiponectin (Acrp30) in patients with HIV-associated lipodystrophy (HIV-LD). Three groups of subjects were studied; HIV-positive subjects with lipodystrophy (HIV-LD; n = 22), HIV-positive subjects without lipodystrophy (HIV; n = 17), and ethnicity- and body mass index-matched healthy control subjects (n = 20). Although total body fat from dual energy x-ray absorptiometry was similar in all three groups, the HIV-LD group had a significantly lower mean proportion of body fat in the limbs +/- SEM (37.2% +/- 2.2%) than either controls (49.8% +/- 1.5%) or HIV subjects (45.7% +/- 2.0%). The HIV-LD group also had the lowest mean insulin sensitivity +/- SEM (5.11 +/- 0.59 mg of glucose/[kg of lean body mass. min] vs. 10.2 +/- 0.72 mg of glucose/[kg of lean body mass. min] in controls and 8.64 +/- 0.69 mg of glucose/[kg of lean body mass. min] in the HIV group). Leptin levels were similar in all three groups and were significantly correlated to total body fat (r = 0.86; p <.001), but these levels did not correlate with either insulin sensitivity or limb fat. Mean Acrp30 levels +/- SEM were lowest in the HIV-LD group (5.43 +/- 0.44 microg/mL vs. 11.2 +/- 1.4 microg/mL in the HIV group and 14.9 +/- 1.8 microg/mL in control subjects). Further, Acrp30 levels were positively correlated with insulin sensitivity (r = 0.610; p <.001) and limb fat (r = 0.483; p <.001). However, the correlation between limb fat and insulin sensitivity disappeared when Acrp30 level and other potential mediators were removed from the association, suggesting that a deficiency in Acrp30 in subjects with HIV-LD may be part of the mechanism for the reduced insulin sensitivity.