Associations between total serum GGT activity and metabolic risk: MESA

Aim: To evaluate associations between total serum GGT activity, metabolic risk factors and prevalent metabolic disease in MESA. Patients & methods: Continuous associations between GGT and fasting blood glucose (FBG), fasting insulin, HbA_1c and Homeostasis Model Assessment Index of Insulin Resistance (HOMA-IR) were evaluated in the entire MESA cohort and in metabolic disease subgroups using linear regression models incrementally adjusted for age, gender, site, race, lifestyle, traditional risk factors and medications. Cross-sectional odds of prevalent impaired FBG, metabolic syndrome and Type 2 diabetes were calculated for GGT quintiles in the entire cohort and in subgroups defined by age (< or ≥65 years) and ethnicity. Results: In multivariable models, significant associations were present between GGT activity and FBG, fasting insulin, HbA_1c and HOMA-IR, with the interaction between GGT and BMI affecting the association between GGT and HOMA-IR as well as the association between BMI and HOMA-IR (p < 0.0001). Adjusted odds ratios (95% CIs) of prevalent impaired FBG, metabolic syndrome and Type 2 diabetes for quintile 5 versus 1 in the entire cohort were 2.4 (1.7-3.5), 3.3 (2.5-4.5) and 2.8 (1.8-4.4), respectively (p < 0.0001). GGT associations weakened with age. The significance of linear trends for increased prevalent metabolic disease by increasing GGT quintile varied by ethnicity. Conclusion: GGT is strongly associated with both cardiovascular and metabolic risk factors, including prevalent metabolic disease, in the MESA cohort.