Relationship between Serum Gamma-glutamyltransferase Levels within Reference Intervals and the Prevalence of Metabolic Syndrome and Diabetes Mellitus in Adults

ABSTRACT

BACKGROUND: This study was conducted to establish reference intervals (RIs) for serum gamma-glutamyltransferase (GGT), and to evaluate the association between serum GGT levels within RIs and the prevalence of metabolic syndrome (MetS) and type 2 diabetes mellitus (DM) in men and women. METHODS: A total of 363 healthy adults (137 men and 226 women) were enrolled for establishing the RIs of serum GGT. A cross-sectional study was conducted with 919 individuals (519 men and 400 women) to evaluate the associations between gender-specific serum GGT RI quartiles and prevalence of MetS and DM. RESULTS: The RIs for serum GGT levels (central 95th percentile ranges) were 9.0-70.6 IU/L and 4.0-31.3 IU/L in men and women, respectively. In men, the odds ratios (ORs) and 95% confidence intervals (CIs) for the prevalence of MetS in 4 serum GGT quartiles (lowest to highest) were 1.0 (reference), 3.6 (0.7-18.0), 8.8 (2.0-39.1), and 17.4 (4.0-75.3), respectively, while the ORs (95% CIs) for the prevalence of DM were 1.0 (reference), 1.0 (0.3-3.0), 1.7 (0.6-4.6), and 2.6 (1.0-6.6), respectively. In women, the corresponding ORs (95% CIs) were 1.0 (reference), 3.3 (0.6-16.6), 5.8 (1.2-27.3), and 18.8 (4.3-82.2) for MetS, respectively, and 1.0 (reference), 1.6 (0.3-9.7), 1.6 (0.3-9.9), and 8.0 (1.7-36.7) for DM, respectively. These significant relationships persisted after adjusting for age, alcohol intake, body mass index, and smoking. CONCLUSIONS: Serum GGT levels, even within RIs, were proportionally associated with prevalence of metabolic syndrome and DM in both men and women. Serum GGT level may be an independent predictor for chronic degenerative diseases.