Nerve growth factor is closely related to glucose metabolism, insulin sensitivity and insulin secretion in the second trimester: a case-control study in Chinese

Abstract Objective: Inflammation-related factors have been shown to play a significant role throughout pregnancy. In this study, we aimed to explore the relationships between selected inflammatory cytokines and gestational diabetes (GDM) in Chinese pregnant women.Design and Methods: This was a 1:1 matched case-control study that included 200 pairs of subjects in the second trimester and 130 pairs of subjects in the third trimester. Serum levels of nerve growth factor (NGF), Interleukin-6 (IL-6), leptin, Interleukin-8 (IL-8), monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-alpha (TNF-α) and Interleukin-1beta (IL-1β) were measured by enzyme immunoassay. The associations of these inflammatory factors with metabolic parameters were analysed.Results: In the second trimester, GDM patients had higher NGF levels and lower IL-8 levels than did normal controls (P<0.001 and P=0.015, respectively). However, in the third trimester, only lower leptin levels were observed in the GDM group (P=0.031). Additionally, in the second trimester, NGF levels were not only positively associated with fasting, 1-h and 2-h glucose levels and the area under curve of glucose (AUCG), but also positively related to insulin sensitivity and secretion, as suggested by fasting insulin, homeostasis model assessment of insulin resistance (HOMA-IR) and homeostasis model assessment index of β-cell secretion (HOMA-β) (all P<0.05). Moreover, IL-6 and leptin levels were positively correlated with HOMA-IR and HOMA-β, and TNF-α levels were positively related to HOMA-IR (all P<0.05). Except for the relationships between NGF and HOMA-β and TNF-α and HOMA-IR, the other correlations still existed even after adjusting for confounding factors (all P< 0.05).Conclusion: In addition to the positive associations of IL-6 and leptin with insulin resistance and secretion, NGF was higher in the GDM patients and strongly linked to glucose metabolism, insulin resistance and pancreatic β cell function in Chinese pregnant women in the second trimester.