What is the optimal range of fasting stress hyperglycemia ratio for all-cause mortality in American adults: An observational study

To date, no studies have been conducted to assess the impact of fasting stress hyperglycemia ratio (SHR) on all-cause mortality. Therefore, the objective of our study is to investigate the association between SHR and all-cause mortality in a population of American adults. The study population was derived from NHANES data spanning from 2005 to 2018. The exposure variable SHR was derived from fasting blood glucose (FBG) and glycosylated hemoglobin (HbA1c%), and the specific calculation formula was as follows: (FBG (mmol/L))/(1.59 × HbA1c (%) − 2.59). The outcome variable was all-cause mortality. A total of 18,457 participants were enrolled in this prospective cohort study. Following a median follow-up period of 90 months, all-cause mortality was observed in 10.32% of the subjects. Cox proportional hazards regression model indicates that there is no significant difference between SHR and all-cause mortality in the fully adjusted model, whether analyzed as a continuous or categorical variable ( P for trend > 0.05). Through the 2-piecewise Cox proportional hazards regression model, we have determined that the inflection point of SHR in relation to all-cause mortality is 0.88. It has also been observed that when the value of SHR is on the left side of the inflection point (SHR ≤ 0.88), there is a significant 77% (HR: 0.23; 95% CI: 0.10–0.50) reduction in all-cause mortality for each additional unit increase in SHR. Conversely, when the value of SHR exceeds 0.88, there is a substantial 2.40-fold (HR: 2.40; 95% CI: 1.61–3.58) increase in the risk of all-cause mortality ( P for log likelihood ratio test < .001). The subgroup analysis results demonstrate that sex has the potential to modify the association between SHR and all-cause mortality within the population exhibiting SHR ≤ 0.88. The relationship between SHR and all-cause mortality follows a U-shaped pattern, where in the lowest risk of death for the average American adult is observed at an SHR value of 0.88. Furthermore, in men with SHR ≤ 0.88, there is a significant inverse relationship between the increase in SHR and the risk of all-cause mortality.