Comparison of Associations of DXA and CT Visceral Adipose Tissue Measures With Insulin Resistance, Lipid Levels, and Inflammatory Markers

Abstract

Background Visceral adipose tissue (VAT) measured by computed tomography (CT) is related to insulin resistance, lipids, and serum inflammatory markers. Our objective was to compare the strength of the associations of visceral adipose tissue (VAT) measured with dual energy x-ray absorptiometry (DXA-VAT) and computed tomography (CT-VAT) with insulin resistance, serum lipids, and serum markers of inflammation. Methodology For 1,117 men age 65 and older enrolled in the Study of Osteoporotic Fractures in Men (MrOS), the cross-sectional associations of DXA-VAT and CT-VAT with Homeostasis Model Assessment of insulin resistance (homa2ir), C-reactive protein (CRP), and HDL cholesterol were estimated with regression models, and compared using a Hausmann test. Results Adjusted for age and body mass index (BMI), DXA-VAT was moderately associated with homa2ir (effect size 0.38, 95% C.I. 0.28 to 0.47) and modestly associated with HDL cholesterol (DXA effect size −0.29, 95% C.I. −0.38 to −0.21). These associations were significantly greater than for CT-VAT with homa2ir (0.30, 95% C.I. 0.24 to 0.37; p-value for effect size difference 0.03) and CT-VAT with HDL cholesterol (-0.22, 95% C.I. −0.29 to −0.15; p-value for difference 0.005). Neither DXA-VAT nor CT-VAT were associated with CRP after adjustment for age and BMI (DXA-VAT effect size 0.14, 95% C.I. −0.04 to 0.32; CT-VAT effect size 0.08, 95% C.I. −0.08 to 0.25; p-value for difference 0.35). Conclusion DXA-VAT has similar or greater associations with insulin resistance, and HDL cholesterol as does CT-VAT in older men, confirming the concurrent validity of DXA-VAT. Investigations of how well DXA measurements of VAT predict incident cardiovascular disease events are warranted.

Central Obesity and Visceral Adipose Tissue Are Not Associated With Incident Atherosclerotic Cardiovascular Disease Events in Older Men

“…VAT is associated with metabolic risk factors such as high‐density lipoprotein cholesterol in both sexes, albeit somewhat more strongly in women 31. Moreover, higher levels of VAT on DXA were associated with lower high‐density lipoprotein cholesterol, higher triglycerides, greater insulin resistance, and lower adiponectin concentrations in this cohort of older men 10. However, the associations between VAT and inflammatory cytokines such as tumor necrosis factor alpha and interleukin‐6 are weak in older men 10.…”

“…Moreover, higher levels of VAT on DXA were associated with lower high‐density lipoprotein cholesterol, higher triglycerides, greater insulin resistance, and lower adiponectin concentrations in this cohort of older men 10. However, the associations between VAT and inflammatory cytokines such as tumor necrosis factor alpha and interleukin‐6 are weak in older men 10. Whether or not the associations of inflammatory cytokines and adipocytokines with central adiposity weaken with advancing age, and whether or not changes of these associations with age varies by sex, is not known.…”

“…We cannot rule out the possibility that measures of VAT using CT or magnetic resonance imaging are associated with incident ASCVD in older men. However, we think that is unlikely since DXA‐VAT is highly correlated with both CT34, 35, 36, 37 and magnetic resonance imaging34, 38 measures of VAT, and since DXA‐VAT is as strongly associated with cardiometabolic ASCVD risk factors as CT‐VAT in older men 10. Finally, we ascertained prior diagnoses of comorbid conditions at baseline by self‐report, and did not have medical records available to confirm self‐reported diagnoses.…”

“…We have previously shown that higher levels of VAT, measured by either computed tomography (CT) or dual energy X‐ray absorptiometry (DXA), are associated with a detrimental ASCVD risk factor profile among older men including lower high‐density lipoprotein cholesterol, higher triglycerides, and greater insulin resistance 10. In spite of this, it is unclear whether VAT or other measures of central adiposity predict ASCVD events in the older population, given that adipose tissue may be a marker of vitality and a low burden of comorbid illness in this age group 11.…”

Effect of Ursolic Acid on Insulin Resistance and Hyperinsulinemia in Rats with Diet-Induced Obesity: Role of Adipokines Expression

“…This proinflammatory profile is evidenced by monocyte chemoattractant protein-1 (MCP-1), interleukin 6 (IL-6), IL-1b, and tumor necrosis factor a (TNF-a) increase, simultaneously with adiponectin and anti-inflammatory adipokines diminution, among other molecules. [6][7][8][9][10] MCP-1 induces macrophage recruitment increasing the proinflammatory gene expression and impairing insulin signaling 11,12 ; IL-1b leads to insulin signaling blockage and progressive loss of the insulin-producing pancreatic b cell 13 ; IL-6 and TNF-a contribute to insulin signaling pathway disruption, and are negatively associated with adiponectin expression, an insulin-sensitizing adipokine. [14][15][16] Hyperinsulinemia constitutes an underlying factor of obesity-related comorbidities and its role in initiating, sustaining, and expanding IR, a T2D hallmark, is relevant.…”