(16-05-06) Serum Gamma-Glutamyl Transpeptidase (GGT) is a Determinant of Insulin Resistance (HOMA-IR) Independent of Adiposity

Ortega E, Koska J, Salbe AD, Tataranni PA, Bunt JC.

Obesity and Diabetes Clinical Research Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, Arizona 85016.

Context. Elevated activities of serum enzymes including alanine amino- [ALT], aspartate amino- [AST], and gamma-glutamyltransferase [GGT]) have been associated with obesity and insulin resistance (IR). ALT is an independent predictor of type 2 diabetes (T2DM) in adult Pima Indians, and GGT predicts T2DM in other adult populations. Objective. Our aim was to establish whether independent relationships exist between either adiposity or IR and hepatic enzymes in a group of Pima Indian children. Patients and Methods. In a cross-sectional study, 44 children (22M / 22 F; 7-11 y) were measured for weight (WT), height, percent body fat (%FAT), and serum activities of ALT, AST, and GGT. Body mass index (BMI, kg/m(2)) was calculated. IR was calculated from fasting plasma concentrations of glucose and insulin (log10) using the HOMA model (HOMA-IR). Results. Hepatic enzymes were positively associated with obesity measures, fasting insulin, and HOMA-IR. GGT was additionally associated with serum lipids and white blood cell count. GGT, but not AST or ALT, was a significant determinant of HOMA-IR independent of age, sex, and either WT, BMI, or %FAT. The model that accounted for the largest portion of the variance in HOMA-IR included WT (beta=0.004; P = 0.008) and GGT (beta = 0.20; P = 0.004; total R(2) = 0.62, P < 0.0001). Conclusion. Significant relationships between adiposity and hepatic enzyme activities already exist during childhood in Pima Indians. Whether or not serum GGT activity predicts the development of T2DM in these children remains to be determined in follow-up studies.

PMID: 16434459 [PubMed - as supplied by publisher]

J Clin Endocrinol Metab. 2006 Jan 24; [Epub ahead of print] Related Articles, Links

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