Association Between Fasting Blood Glucose and All-Cause Mortality in a Rural Chinese Population: 15-Year Follow-Up Cohort Study

Introduction: The worldwide prevalence of diabetes has been increasing for decades; diabetes can lead to serious health problems and even death, but the effects of maintaining low fasting blood glucose (FBG) remain controversial. The purpose of this study was to investigate the relationship between FBG levels and all-cause mortality in a long-term follow-up cohort and to find a relatively safe range of FBG levels. Methods: This study included 17,902 adults from a community-based cohort study in rural China who were prospectively followed from 2003 to 2018. Generalized estimating equations were used to evaluate the association between FBG and all-cause mortality, adjusting for pertinent covariates and auto-correlations among siblings. Results: A total of 1053 (5.9%) deaths occurred during 15 years of follow-up. There was a significant U-shaped association between all-cause mortality and FBG. Compared with the reference group (FBG of 5.6 – < 6.1 mmol/l), the risk of death among individuals with FBG levels < 5.6 mmol/l significantly increased by 38% (OR 1.34; 95% CI 1.13–1.59), while the risk of death among individuals with FBG ≥ 6.1 mmol/l or participants with a self-reported history of diabetes significantly increased by 51% (OR 1.49; 95% CI 1.20–1.85). Additionally, the U-shaped association remained steady in any stratification of risk factors. Conclusion: Our study showed a significant U-shaped relationship between FBG levels and risk of all-cause mortality in this rural Chinese population. When FBG was within the range of 5.6 – < 6.1 mmol/l, the risk of all-cause mortality was the lowest.