Ethnicity, Insulin Resistance, and Inflammatory Adipokines in Women at High and Low Risk for Vascular Disease

Abstract

OBJECTIVE -We sought to compare the relationship between body composition, insulin resistance, and inflammatory adipokines in Aboriginal Canadian women, who are at high risk of vascular disease, with white women. RESEARCH DESIGN AND METHODS -A subgroup of the First Nations Bone HealthStudy population, consisting of 131 Aboriginal women and 132 matched white women, was utilized. Body composition was determined by whole-body dual X-ray absorptiometry, and blood analytes were measured after an overnight fast.RESULTS -After excluding individuals with diabetes, A1C, BMI, percent trunk fat, and homeostasis model assessment of insulin resistance (HOMA-IR) were greater in First Nation women compared with white women, whereas adiponectin, retinol binding protein (RBP)4, and insulin-like growth factor binding protein-1 (IGFBP-1) were lower. First Nation women had more trunk fat for any given level of total fat than white women. There were no differences in resistin, leptin, tumor necrosis factor (TNF)-␣, or C-reactive protein (CRP) levels between First Nation and white women. Insulin resistance correlated with leptin and inversely with adiponectin levels in both First Nation and white women. There were weak correlations between insulin resistance and TNF-␣, interleukin-6, and CRP, but these were not significant after correction for body fat. No correlation was found between RBP4 and insulin resistance. ANCOVA revealed a higher HOMA-IR adjusted for total body fat in First Nation women than in white women (P ϭ 0.015) but not HOMA-IR adjusted for trunk fat (P Ͼ 0.2).CONCLUSIONS -First Nation women are more insulin resistant than white women, and this is explained by trunk fat but not total fat. Despite the increased insulin resistance, inflammatory adipokines are not significantly increased in First Nation women compared with white women. Diabetes Care 30:286 -291, 2007A n increased prevalence of vascular disease in insulin-resistant states such as pre-diabetes, type 2 diabetes, and the metabolic syndrome has been long recognized (1). There is considerable debate whether insulin resistance is the primary event in atherosclerosis, with consequent activation of proinflammatory signaling pathways, or, alternatively, whether low-grade inflammation and subsequent insulin resistance accounts for the association of diabetes and vascular disease (2).Aboriginal Canadian populations, which include First Nation, Metis, and Inuit individuals (3), have an increased prevalence of atherosclerosis and cardiovascular and peripheral vascular disease (4,5). First Nations are Aboriginal individuals signatory to treaties and/or recognized by the Canadian Federal Government as a fiduciary responsibility and represent the large majority of Aboriginal individuals living in Canada (3). While type 2 diabetes is more prevalent among Canadian men than women in the general population, the reverse is true for the First Nation population (6,7). In the First Nation population, obesity is more prevalent among men than women, but the prevalence of metabolic ...

Serum Levels of Adipokine Retinol-Binding Protein-4 in Relation to Renal Function

“…A positive association between RBP-4 levels and insulin resistance is also shown in obese and nonobese adolescents (18); in subjects with obesity, IGT, or type 2 diabetes; in nonobese, nondiabetic subjects with a strong family history of type 2 diabetes (5); and in nonobese individuals without a family history or diagnosis of diabetes (23). In contrast, no correlation between RBP-4 and insulin resistance is found in Aboriginal Canadian women and white women (24). Cho et al (6) found significantly different RBP-4 levels between patients with normal glucose tolerance on one hand and IGT and diabetes on the other hand.…”

Adipokines and Insulin Resistance

“…Genetic studies reported an association of RBP4 SNPs and insulin resistance, impaired insulin secretion, and/or type 2 diabetes (139,140). Other studies, however, failed to establish an association of RBP4 levels with obesity (141-143), insulin resistance (141-144), type 2 diabetes (144) or components of the metabolic syndrome (145). This discrepancy may be explained in part through methodological differences in the measurement of RBP4 (146) as well as differences in the study populations.…”

Circulating Retinol-Binding Protein-4 Concentration Might Reflect Insulin Resistance–Associated Iron Overload

“…At least two recent studies (7,8) did not observe a relationship between RBP4 and insulin resistance in women. Although some problems exist with serum RBP4 measurements (9), RBP4 mRNA was in fact downregulated in subcutaneous abdominal adipose tissue in postmenopausal women (7).…”