Circulating interleukin-6 in relation to adiposity, insulin action, and insulin secretion.
OBJECTIVE
Plasma concentrations of interleukin-6 (IL-6), a proinflammatory cytokine produced and released in part by adipose tissue, are elevated in people with obesity and type 2 diabetes. Because recent studies suggest that markers of inflammation predict the development of type 2 diabetes, we examined whether circulating plasma IL-6 concentrations were related to direct measures of insulin resistance and insulin secretory dysfunction in Pima Indians, a population with high rates of obesity and type 2 diabetes.


METHODS
Fasting plasma IL-6 concentrations (enzyme-linked immunosorbent assay), body composition (DXA), insulin action (M; hyperinsulinemic euglycemic clamp), and acute insulin secretory responses to glucose (25 g intravenous glucose tolerance test) were measured in 58 Pima Indians without diabetes (24 women, 34 men).


RESULTS
Fasting plasma IL-6 concentrations were positively correlated with percentage of body fat (r = 0.26, p = 0.049) and negatively correlated with M (r = -0.28, p = 0.031), but were not related to acute insulin response (r = 0.13, p = 0.339). After adjusting for percentage of body fat, plasma IL-6 was not related to M (partial r = -0.23, p = 0.089).


CONCLUSIONS
Fasting plasma IL-6 concentrations are positively related to adiposity and negatively related to insulin action in Pima Indians. The relationship between IL-6 and insulin action seems to be mediated through adiposity.
Vozarova
B
B
Clinical Diabetes and Nutrition Section, National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, Arizona 85016, USA. bvozarov@mail.nih.gov
Weyer
C
C
Hanson
K
K
Tataranni
P A
PA
Bogardus
C
C
Pratley
R E
RE
D000273:Adipose Tissue / Q000378:metabolism*; D000293:Adolescent; D000328:Adult; D001130:Arizona; D015415:Biomarkers; D001823:Body Composition; D003924:Diabetes Mellitus, Type 2 / Q000209:etiology; D004797:Enzyme-Linked Immunosorbent Assay; D005215:Fasting; D005260:Female; D015309:Glucose Clamp Technique; D005951:Glucose Tolerance Test; D006801:Humans; D007198:Indians, North American; D007328:Insulin / Q000097:blood* / Q000378:metabolism; D007333:Insulin Resistance; D000078790:Insulin Secretion; D015850:Interleukin-6 / Q000097:blood*; D008137:Longitudinal Studies; D008297:Male; D009765:Obesity / Q000097:blood / Q000150:complications*
D015415:Biomarkers; D007328:Insulin; D015850:Interleukin-6