There are inconsistencies in the conclusions about the relationship between fasting blood glucose (FBG) and all-cause and specific-cause mortality among adults in previous studies, so it is necessary to be further explored.

To analyze the association between FBG level and the risk of all-cause mortality, cardiovascular disease mortality and cancer-related mortality in adults, providing dependable theoretical basis for the prevention and control of priority diseases.

This is a prospective cohort study, and the cohort was established in November 2010. A total of 9 280 residents aged 18 years or older who had lived at least 6 months per year in 12 counties (cities and districts) of Guizhou Province were selected for baseline survey. All participants in the baseline survey were followed up in 2020 and 2023, respectively.Participants were assigned into four groups based on their baseline FBG level: low fasting glucose (LFG) , normal fasting glucose (NFG) , impaired fasting glucose (IFG) , diabetes (DM) , the number of participants in each group is 437, 6 210, 2 035, 427, respectively. COX proportional hazard models were used to estimate hazard ratio (HR) and corresponding 95% confidence interval (95%CI) for evaluating the association between FBG and risk of all-cause mortality, specific-cause mortality. Restricted cubic spline analysis was performed to analysis the dose-response relationship. Subgroup analysis was carried out with different characteristic including sex, age and BMI.

A total of 9 109 subjects were included in this study, and 589 deaths occurred during a median follow-up period of 11.69 years. COX proportional hazard regression analysis showed that after adjusting for related confounding factors, the risk of all-cause mortality increased by 10% for every 1-unit increase in FBG (HR=1.10, 95%CI=1.06-1.15) , especially, comparing with NFG, with DM significant increased the risk of all-cause mortality (HR=1.59, 95%CI=1.18-2.17) and cancer-related mortality (HR=2.16, 95%CI=1.03-4.49) , respectively.Restricted cubic spline analysis showed a linear dose-response relationship between FBG and the risk of all-cause mortality and cancer-related mortality. Subgroup analysis showed that the all-cause mortality was increasing in female (HR=2.01, 95%CI=1.27-3.20) , ≥45 years old (HR=1.57, 95%CI=1.13-2.16) , BMI<24.0 kg/m² (HR=1.45, 95%CI=1.11-2.43) , BMI≥24.0 kg/m² (HR=1.67, 95%CI=1.01-2.76) with DM, cancer-related mortality was increased only in female (HR=2.39, 95%CI=1.11-5.14) , ≥45 years old (HR=6.62, 95%CI=1.61-9.76) , BMI<24.0 kg/m² (HR=2.69, 95%CI=1.11-6.52) with DM.

FBG level was linearly positively correlated with mortality, DM increased the risk of all-cause mortality and cancer-related mortality, effective measures should be taken to control blood glucose at an ideal level.