Body mass index mediates the association between neutrophil-to-lymphocyte ratio and impaired fasting glucose: evidence from a five-year follow-up study

Previous studies have found that impaired fasting glucose (IFG) is associated with obesity, as measured by body mass index (BMI), and the neutrophil-to-lymphocyte ratio (NLR). However, few studies have investigated the effect of the interaction between the BMI and NLR on IFG in Chinese adults. A total of 1067 individuals who did not suffer from IFG at baseline and regularly underwent a physical examination in the hospital annually were selected for this study. We followed up with those participants and recorded their clinical baseline data, including general information, physical examination indexes, the blood glucose index, routine blood examination data, blood lipid levels and lifestyle factors. All participants were divided into four groups, including the isolated obesity group, the isolated higher NLR group, the interaction group and the control group. By observing and recording the changes in FPG and the incidence of IFG (IPI) in the four groups, we explored the association between NLR and IPI in the different BMI categories. From 2012 to 2017, 100 participants suffered from IFG, and the cumulative incidence rate of IFG was 9.37% (100/1067). The IPIs in the control group, isolated higher NLR group, isolated obesity group and interaction group were 6.2%, 6.2%, 8.0% and 17.1%, respectively. The prevalence of IFG increased by 9.1% among individuals who were obese and had a higher NLR compared to those who were non-obese and did not belong to the higher NLR group. This indicates the presence of an interaction effect between NLR and obesity on the development of IFG. In summary, our study found that the interaction between obesity and NLR significantly increased the prevalence of IFG in Chinese adults, and this, a cohort five-year follow-up study, is the first study to disclose the associations among the BMI, NLR and IFG.