GPT and diabetes mellitus: Several cross-sectional and prospective studies have shown that deterioration of glucose tolerance and incidence of type 2 diabetes mellitus (T2DM) in the general population are associated with elevated liver enzymes, even though with some discrepancies among different ethnic groups [1–7]; ALT was the main enzyme involved in the majority of studies, while in others the enzyme was γGT (γ-glutamil transferase) [2–7].