Insulin-like growth factor-1 and non-alcoholic fatty liver disease: a systemic review and meta-analysis

The prevalence of non-alcoholic fatty liver disease (NAFLD) is rapidly increasing worldwide. A number of researchers have studied the relationship between Insulin-like growth factor-1(IGF-1) and NAFLD. However, the results are controversial. This meta-analysis, aimed to systemically evaluate the correlation between IGF-1 and NAFLD.

We searched for four online databases: PubMed, Web of Science, Embase and CNKI up to Feb 2018. We then applied a random-effects model to evaluate the overall effect sizes by calculating Standard mean difference (SMD) and its 95% confidence intervals (CIs).

Twelve articles were included in this meta-analysis. The pooled analysis showed that the level of IGF-1 in the control group was significantly higher than that in the NAFLD group. (SMD: 1.00, 95% CI: 0.54-1.46, P < 0.00001). However, significant heterogeneity was discovered among the included studies (P < 0.00001, I² = 96%). Then a series of subgroup analyses were performed. Compared to the nonalcoholic steatohepatitis (NASH) group, the level of IGF-1 was significantly higher in the Non- or probable-NASH group (SMD: 1.42, 95% CI: 0.25-2.58, P = 0.02). The level of IGF-1 in patients with increased insulin resistance (SMD: 0.49; 95% CI: 0.36-0.63; P < 0.00001) and high Body Mass Index (SMD: 0.50; 95% CI: 0.22-0.79; P < 0.05) were significantly lower than healthy control. In addition, the same conclusion were found in studies carried out in Asia and Europe (Asia: SMD: 0.69, 95% CI: -0.29-1.66, P = 0.17; Europe: SMD: 0.89, 95% CI: 0.41-1.38, P < 0.05).

The level of IGF-1 is down-regulated in NAFLD patients compared to healthy controls, suggesting that IGF-1 might be used as a potential biomarker and therapeutic target for NAFLD.