P-9 Serum resistin levels among Asian Indians: Relationship to inflammatory marker CRP and adipocytokine, leptin

Abstract

Obesity, especially visceral obesity, shows a strong correlation with insulin resistance. Recent studies suggested that γ-glutamyl transferase (GGT) levels were associated with the development of MS and Type 2 diabetes. In this study, we investigated the associations of GGT levels with abdominal fat distribution, adipokines and insulin resistance in non-diabetic subjects. Methods: We enrolled 94 healthy subjects, aged 30-69 years (mean age 47.3±13.4 years, 47.8% male). Subjects with daily alcohol consumption larger greater than 20g were excluded. Lipid profiles, fasting plasma glucose (FPG), insulin, and liver enzyme levels were measured. Adiponectin and retinol binding protein4 (RBP-4) levels were determined by ELISA. Insulin resistance (IR) was examined by HOMA-IR. Abdominal fat distribution was measured by a computed tomography (CT) scan. Results: Mean values of body mass index (BMI), abdominal visceral fat area (VFA), and subcutaneous fat area in subjects were 24.1±2.8 kg/m2, 91.4±57.9 cm2, and 122.4±56.8 cm2, respectively. Mean values of adiponectin were 7.01±3.33 μg/ml and RBP-4 levels were 71.2±25.0 μg/ml. We defined IR as cases with HOMAIR levels greater than the median value of HOMA-IR. Subjects with IR were more likely to be men and had significantly higher BMI, waist to hip ratio (WHR), blood pressure, triglyceride, FPG, and abdominal VFA (p<0.05), and had lower levels of adiponectin (p<0.01) than those without IR. In linear regression analysis after adjustment for age and sex, GGT levels showed strong positive correlations with WHR, VFA, HOMA-IR, and RBP-4 levels (r values; 0.45, 0.36, 0.31, and 0.43 respectively, p < 0.001), and a strong negative correlation with adiponectin levels (r value; -0.22, p<0.01). Alanine transaminase (ALT) showed a strong positive correlation with HOMA-IR (r value; 0.34, p<0.01), while aspartate transaminase (AST) showed a strong positive correlation with RBP-4 levels (r value; 0.24, p<0.05). Subjects in the highest tertile of GGT levels had higher BMI, WHR, VFA, RBP-4 and HOMA-IR, but had lower levels of adiponectin compared with subjects in the lowest tertile (p<0.05). In logistic regression analysis, the odds ratio (OR) for the presence of IR after adjustment for age and sex was significantly increased in the highest tertile of GGT levels [OR (95% CI); 1 vs. 1.15 (0.37-3.56) vs. 4.25 (1.19-15.17)]. However, OR in the highest tertile remained non significant after adjustment for VFA and BMI. Conclusion: Our data showed that GGT levels were significantly related with BMI, WHR, abdominal VFA, HOMA-IR, and adiponectin levels after adjustment for age and sex in nondiabetic subjects. GGT levels may be a useful indicator of abdominal visceral obesity and insulin sensitivity in these subjects.