Increased serum/plasma fibroblast growth factor 21 in type 2 diabetes mellitus: a systematic review and meta-analysis.

Objectives Fibroblast growth factor-21 (FGF-21) plays an important role in glucose and lipid metabolism. This study aims to systemically review the evidence regarding the relationship between the FGF-21 levels and type 2 diabetes mellitus (T2DM), as well as the related influential factors. Methods Research related to plasma/serum FGF-21 levels in patients with T2DM and healthy controls were searched in PubMed, EMBASE and The Cochrane Library databases (up to 31 March 2017). Pooled standard mean difference (SMD) with 95% CI was calculated by fixedeffect or random-effect model analysis. Heterogeneity test was performed by the Q-statistic and quantified using I2, and publication bias was evaluated using a funnel plot and Egger's linear regression test. Results In total, 317 articles were obtained after searching databases, and 11 studies with 866 patients with T2DM and 629 controls were finally included. Metaanalysis revealed that, compared with the control group, the T2DM group had a significantly higher plasma/serum FGF-21 level (p < 0.001), with the SMD of 1.34% and 95% CI (0.70 to 1.98). Meta-regression analysis and subgroup analyses suggested that body mass index (BMI), triglycerides (TG) and total cholesterol (TC) were likely related to the observed FGF-21 differences between two groups. Conclusions Overall, our study suggests that patients with T2DM have significantly higher plasma/serum FGF21 levels, and the FGF-21 levels were influenced by BMI, TC and TG.