Poster Topical Area: Energy and Macronutrient Metabolism
Location: Hall D
Poster Board Number: 443
Objective. Recent evidence suggests that bioimpedance devices can non-invasively detect physiological dysfunction at the cellular level by measuring changes in membrane capacitance (CM), an impedance parameter that reflects membrane structure and integrity. However, it is not known whether CM is influenced by insulin resistance, a common antecedent of chronic metabolic diseases such as type 2 diabetes and cardiovascular disease. We therefore tested the hypotheses that, 1) CM would be significantly higher in non-diabetic insulin-resistant adults compared with insulin-sensitive adults, and 2) associations would exist between CM and endpoints reflecting glycemic status.
Methods. This cross-sectional study used a subsample of non-diabetic adults, 18-49 years old (n=2,212, 45% female, 43% Non-Hispanic white, 22% Non-Hispanic black, and 34% Hispanic) from the 1999 – 2004 National Health and Nutrition Examination Survey III. Subjects were divided into groups by sex and insulin-resistance status (HOMA-IR > or 2.6). Analysis of covariance with Tukey-Kramer post-hoc test was used to compare differences between groups. Bivariate and partial correlations were used to determine associations between CM and endpoints reflecting glycemic status (HbA1c, fasting insulin, HOMA-IR). Covariates included age, race, height, fat/lean mass from DXA, and medication use.
Results. In women, CM was associated with HbA1c (%) (r= 0.34; p< 0.0001), fasting insulin (uU/ml) (r= 0.46; p<0.0001), and HOMA-IR (r= 0.47; p<0.0001). After adjusting for covariates, insulin-resistant women had higher CM than insulin-sensitive women (8.19 ± 0.07 vs 8.80 ± 0.12 nF/m2; p< 0.01). Conversely, in men, CM was not associated with HbA1c (%) (r= 0.05; p=0.08), but was associated with fasting insulin (r= 0.10; p< 0.01) and HOMA-IR (r= 0.19; p< 0.01). After adjusting for body composition, insulin-resistant men showed no significant difference in CM compared to insulin-sensitive men (11.28 ± 0.10 vs 11.27 ± 0.11 nF/m2; p=0.95).
Conclusion. CM may reflect insulin-resistance in non-diabetic women, but not men. Future research will 1) explore the obeserved gender differences in CM, and 2) evaluate the association between CM and insulin sensitivity measured by the euglycemic clamp.
Valene Garr Barry
University of Alabama at Birmingham