Time in blood glucose range 70 to 180 mg/dL and survival rate in critically ill patients: A retrospective observational study

ABSTRACT Objective Time in targeted blood glucose range (TIR) 70-140 mg/dL has been associated with an increased risk of mortality in critically ill patients. Nevertheless, it remains unclear whether TIR is associated with 28-day mortality in critically ill patients under glycemic control with a less tight target glucose range of 70-180 mg/dL. We aimed to assess whether TIR 70-180 mg/dL was associated with 28-day mortality and to identify the optimal TIR. Design A retrospective observational study. Setting Data from a tertiary care centre in Japan, from 1 January 2016 through 31 October 2019. Participants 1,230 adult patients admitted to the intensive care unit for more than three days. Outcome measure The primary outcome was 28-day mortality. Results Of 1,230 patients, patients with HbA1c ≥6.5% had a higher 28-day mortality than those with <6.5% (32.0% vs. 22.7%; p=0.003). In the multivariate logistic regression, TIR <80% was associated with an increased risk of 28-day mortality in patients with HbA1c <6.5% with an adjusted odds ratio (OR) of 1.88 (95% confidence interval [CI]: 1.36-2.61). When using 10% incremental TIR as a categorical variable, lower TIR was associated with worse 28-day mortality compared to TIR ≥90% in patients with HbA1c <6.5% (e.g., adjusted OR of TIR <60%, 3.62 [95%CI 2.36-5.53]). Similar associations were found in the analyses using the COX proportional hazards model. In addition, sensitivity analyses using TIR of the first three days showed that the overall associations were consistent with primary analyses. Conclusions Our study demonstrated that lower TIR 70-180 mg/dL was associated with higher 28-day mortality in nondiabetic critically ill patients. Article Summary Strengths and limitations of this study This is the first study to evaluate the association between less tight TIR (70-180 mg/dl) and mortality in critically ill patients. We found consistent results in the analyses using logistic regression model and Cox proportional hazard model. The primary findings were also observed in the analysis using TIR in the first three days. We did not use a continuous glucose monitoring device to calculate TIR. Due to the nature of the single-centre study design, the generalizability of the findings might be limited.