Time in Target Blood Glucose Range Independently Associated With Mortality in Critically Ill Patients

Critically ill patients who maintained blood glucose levels between 70 to 140 mg/dL at least 80% of the time had increased survival compared with those who did not.

Critically ill patients receiving intravenous insulin infusion face better odds of survival when they spend more time in a targeted blood glucose range, especially if their antecedent glucose control is good, according to study results published in Chest.

Researchers conducted a retrospective analysis of 9028 critically ill patients who received intravenous insulin infusion in intensive care units according to Intermountain Healthcare’s infusion protocol (eProtocol-insulin). The goal of the study was to evaluate the relationship between time in targeted blood glucose range (70-139 mg/dL) and clinical outcomes, particularly mortality risk. Diabetic status and antecedent glycemic control (highest recorded glycosylated hemoglobin in prior 3 months) were assessed as potential confounding factors. Good antecedent glycemic control was defined as hemoglobin A1c ≤6.5%.

Of included patients, 53.2% had diabetes. Compared with patients without diabetes, those with diabetes had a significantly lower median percentage of time in targeted glucose range (84.1% vs 64.5%, respectively; P <.001). Patients with diabetes also had a higher mortality rate (17.3% vs 15.6%; P =.03).

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On average, 30-day mortality rate was lower in patients with diabetes who were in the targeted blood glucose range ≥80% of the time vs those who remained in range <80% of the time (14.6% vs 18.3%, respectively; P =.003). This finding was also true for patients without diabetes (11.8% vs 21.3%; P <.001). Furthermore, time in range ≥80% was independently associated with reduced mortality in patients without diabetes (odds ratio [OR], 0.52; P <.001), patients with diabetes (OR, 0.69; P =.001), and patients with good antecedent glycemic control (OR, 0.50; P <.001), but not those with poor antecedent glycemic control (OR, 0.86; P =.40).

Limitations to this study included its observational design, which restricted ability to infer causality.

“Critically ill patients who maintained blood glucose levels between 70-140 mg/dL at least 80% of the time…had increased survival compared to those who did not,” said the researchers. “This finding persisted in non-diabetic patients and diabetic patients with good antecedent control, but was not present in patients with poor antecedent control, suggesting tight glucose control in the [intensive care unit] may not be as important in poorly controlled diabetic patients.”

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Lanspa MJ, Krinsley JS, Hersh AM, et al. Percent of time in range 70-139 mg/dL is associated with reduced mortality among critically ill patients receiving intravenous insulin infusion [published online June 12, 2019]. CHEST. doi:10.1016/j.chest.2019.05.016