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

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, 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.