Association between retinol-binding protein 4 concentrations and gestational diabetes mellitus (A1GDM and A2GDM) in different pregnancy and postpartum periods

Retinol-binding protein 4 (RBP4) circulating levels and gestational diabetes mellitus: a systematic review and meta-analysis

Background

Gestational diabetes mellitus (GDM) is a prevalent condition where diabetes is diagnosed during pregnancy, affecting both maternal and fetal outcomes. Retinol-binding protein 4 (RBP4) is a circulating adipokine which belongs to the lipocalin family and acts as a specific carrier protein that delivers retinol (vitamin A) from the liver to the peripheral tissues. Growing data indicate that circulating RBP4 levels may positively correlate with GDM. Thus, this systematic review and meta-analysis aimed to investigate the potential relationship between circulating RBP4 levels and GDM when measured at various stages of pregnancy.

Methods

MEDLINE, CINAHL, EMCARE, EMBASE, Scopus, and Web of Science databases were searched to identify studies comparing pregnant women with and without GDM, whose circulating RBP4 levels were measured in at least one pregnancy trimester. Findings were reported using standardized mean difference (SMD) and random-effects models were used to account for variability among studies. Furthermore, the risk of bias was assessed using the RoBANS tool.

Results

Out of the 34 studies identified, 32 were included in the meta-analysis (seven with circulating RBP4 levels measured in the first trimester, 19 at 24-28 weeks, and 14 at >28 weeks of pregnancy). RBP4 levels were statistically higher in the GDM group than in controls when measured during all these pregnancy stages, with the noted RBP4 SMD being 0.322 in the first trimester (95% CI: 0.126-0.517; p < 0.001; 946 GDM cases vs. 1701 non-GDM controls); 0.628 at 24-28 weeks of gestation (95% CI: 0.290-0.966; p < 0.001; 1776 GDM cases vs. 1942 controls); and 0.875 at >28 weeks of gestation (95% CI: 0.252-1.498; p = 0.006; 870 GDM cases vs. 1942 non-GDM controls). Significant study heterogeneity was noted for all three pregnancy timepoints.

Conclusion

The present findings indicate consistently higher circulating RBP4 levels in GDM cases compared to non-GDM controls, suggesting the potential relevance of RBP4 as a biomarker for GDM. However, the documented substantial study heterogeneity, alongside imprecision in effect estimates, underscores the need for further research and standardization of measurement methods to elucidate whether RBP4 can be utilized in clinical practice as a potential GDM biomarker.

Systematic review registration

PROSPERO (CRD42022340097: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022340097).

Exploring the mediating role of serum retinol-binding protein 4 in the relationship between sleep quality and insulin resistance in pregnant women

AIMS

We aimed to explore the mediating role of plasma retinol-binding protein 4 (RBP4) in the relationship between sleep quality and insulin resistance (IR) among pregnant women.

METHODS

We conducted a cross-sectional study including 263 pregnant women in the first trimester. Sleep quality was evaluated by Pittsburgh Sleep Quality Index (PSQI). The ELISA and homeostasis model assessment (HOMA) was used to analyze plasma RBP4 and estimate IR. The mediating model was used to analyze the mediating role of RBP4 in the relationship between PSQI score and IR.

RESULTS

In the multivariable linear regression model, the three terms were positively related with each other, PSQI score was positively associated with IR levels (β = 0.55, p < 0.05). In the mediating model, RBP4 levels mediated completely the relationship between PSQI scores and IR levels (β = 0.29, p < 0.0001). The indirect effect of RBP4 in the relation between sleep quality and IR explained 89.10% of total effect.

CONCLUSIONS

RPB4 may play a complete mediating role in the relation between sleep quality and insulin resistance in early pregnancy. Improvements in sleep quality in the first trimester may provide a pathway to reduce plasma RBP4, which is beneficial for less IR and GDM prevention.

Emerging Protein Biomarkers for the Diagnosis or Prediction of Gestational Diabetes-A Scoping Review

Introduction: Gestational diabetes (GDM), defined as hyperglycemia with onset or initial recognition during pregnancy, has a rising prevalence paralleling the rise in type 2 diabetes (T2DM) and obesity. GDM is associated with short-term and long-term consequences for both mother and child. Therefore, it is crucial we efficiently identify all cases and initiate early treatment, reducing fetal exposure to hyperglycemia and reducing GDM-related adverse pregnancy outcomes. For this reason, GDM screening is recommended as part of routine pregnancy care. The current screening method, the oral glucose tolerance test (OGTT), is a lengthy, cumbersome and inconvenient test with poor reproducibility. Newer biomarkers that do not necessitate a fasting sample are needed for the prompt diagnosis of GDM. The aim of this scoping review is to highlight and describe emerging protein biomarkers that fulfill these requirements for the diagnosis of GDM. Materials and Methods: This scoping review was conducted according to preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines for scoping reviews using Cochrane Central Register of Controlled Trials (CENTRAL), the Cumulative Index to Nursing & Allied Health Literature (CINAHL), PubMed, Embase and Web of Science with a double screening and extraction process. The search included all articles published in the literature to July 2020. Results: Of the 3519 original database citations identified, 385 were eligible for full-text review. Of these, 332 (86.2%) were included in the scoping review providing a total of 589 biomarkers studied in relation to GDM diagnosis. Given the high number of biomarkers identified, three post hoc criteria were introduced to reduce the items set for discussion: we chose only protein biomarkers with at least five citations in the articles identified by our search and published in the years 2017-2020. When applied, these criteria identified a total of 15 biomarkers, which went forward for review and discussion. Conclusions: This review details protein biomarkers that have been studied to find a suitable test for GDM diagnosis with the potential to replace the OGTT used in current GDM screening protocols. Ongoing research efforts will continue to identify more accurate and practical biomarkers to take GDM screening and diagnosis into the 21st century.

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.