The association of plasma levels of liver enzymes and risk of gestational diabetes mellitus: a systematic review and dose–response meta-analysis of observational studies

Relationship between liver enzymes such as gamma-glutamyl transferase (GGT), alanine aminotransferase (ALT), aspartate transaminase (AST) and alkaline phosphatase and risk of gestational diabetes mellitus (GDM) is a controversial issue. The aim of this systematic review and dose–response meta-analysis was to investigate the association between liver enzymes and risk of GDM in observational studies. A comprehensive systematic literature search was conducted in MEDLINE/PubMed, SCOPUS and Web of Science databases up to September 2019. Combined odds ratios (ORs) with 95% confidence intervals (CIs) were evaluated by DerSimonian and Laird random-effects models. Dose–response analyses of these relationships were also carried out. Eight studies with 25,451 participants containing 2549 cases were included in this study. Pooled results showed a significant association between GGT levels and risk of GDM (OR 2.10, 95% CI 1.14–3.86, I2 84%). In addition, random-effects model indicated a dramatic and direct significant association between GGT and risk of GDM in nonlinear (p