The effect of blood glucose variability on the survival of patients in the intensive care unit: a prospective observational study

Although hypoglycemia and hyperglycemia are common in patients in the intensive care unit (ICU) and may negatively impact treatment outcomes, glycemic variability has recently gained attention as a promising risk factor in these patients. This study investigated the impact of hypoglycemia, hyperglycemia and glycemic variability on the outcomes of ICU patients. Daily blood glucose levels measured for the study participants were classified as within the reference range of 110–180 mg/dL or outside the reference range at <110 mg/dL or >180 mg/dL. Glycemic variability was classified as a fluctuation in daily blood glucose levels by >70 mg/dL. These measurements were standardized by dividing the number of daily blood glucose levels and glycemic variability outside the reference range by the number of daily levels within the reference range, which yielded the glycemic ratio (GR) and delta (∆)-glucose ratio (∆GR), respectively, and were compared between survivors and non-survivors. A total of 358 patients were prospectively assessed in this study. Our results showed that GR was 0.74 in survivors and 1.04 in non-survivors (p: 0.002), whereas ∆GR was 0.73 in survivors and 1.0 in non-survivors (p < 0.001). Additionally, the mortality rates were 54.4% and 30.6% for patients with an overall mean ∆glucose >70 mg/dL and <70 mg/dL (p < 0.001), respectively. Altogether, an increase in overall mean ∆glucose, ∆GR and GR resulted in an increased mortality risk in hypoglycemic and hyperglycemic ICU patients.

Blood glucose control; Glycemic variability; Hyperglycemia; Intensive care unit; Mortality

[1] Montori VM. Hyperglycemia in acutely ill patients. JAMA. 2002; 288: 2167.

[2] Sakharova OV, Inzucchi SE. Endocrine assessments during critical illness. Critical Care Clinics. 2007; 23: 467–90.

[3] Vanhorebeek I, Van den Berghe G. Diabetes of injury: novel insights. Endocrinology and Metabolism Clinics of North America. 2006; 3: 859–872.

[4] Umpierrez GE, Isaacs SD, Bazargan N, You X, Thaler LM, Kitabchi AE. Hyperglycemia: an independent marker of in-hospital mortality in pa-tients with undiagnosed diabetes. The Journal of Clinical Endocrinology & Metabolism. 2002; 87: 978–982.

[5] Mehta RL. Glycemic control and critical illness: is the kidney involved?Journal of the American Society of Nephrology. 2007; 18: 2623–2627.

[6] Çelik S, Olgun N. Hypoglycemia and hyperglycemia in intensive care unit. Yoğun Bakım Hemşireliği Dergisi. 2016; 20: 57–64.

[7] Krinsley JS, Grover A. Severe hypoglycemia in critically ill patients: risk factors and outcomes. Critical Care Medicine. 2007; 35: 2262–2267.

[8] Chang C, Hsieh C, Huang J, Huang I. Acute and chronic fluctuations in blood glucose levels can increase oxidative stress in type 2 diabetes mellitus. Acta Diabetologica. 2012; 49: 171–177.

[9] Durmaz Akyol A. Diabetes and Intensive Care Patients. Yoğun Bakım Hemşireliği Dergisi. 2009; 13: 30–39.

[10] Upreti V, Singh M, Singh Y, Kannapur A, Nakra M, Kotwal N. Effect of glycemic variability on mortality in ICU settings: a prospective observational study. Indian Journal of Endocrinology and Metabolism. 2018; 22: 632.

[11] Chang C, Hsieh C, Huang J, Huang I. Acute and chronic fluctuations in blood glucose levels can increase oxidative stress in type 2 diabetes mellitus. Acta Diabetologica. 2012; 49: 171–177.

[12] Brownlee M. The pathobiology of diabetic complications. Diabetes. 2005; 54: 1615–1625.

[13] Donati A, Damiani E, Domizi R, Botticelli L, Castagnani R, Gabbanelli V, et al. Glycaemic variability, infections and mortality in a medical-surgical intensive care unit. Critical Care & Resuscitation. 2014; 16: 13–23.

[14] Krinsley JS. Glycemic variability and mortality in critically ill patients: the impact of diabetes. Journal of Diabetes Science and Technology. 2009; 3: 1292–1301.

[15] Zuo Y, Kang Y, Yin W, Wang B, Chen Y. The association of mean glucose level and glucose variability with intensive care unit mortality in patients with severe acute acute pancreatitis. Journal of Critical Care. 2012; 27: 146–152.

[16] Chen QY, Zhang DH, Zhang XF, Wang LM, Guan JH. The relationship between the levels and variability of blood glucose and the prognosis of massive cerebral infarction. Zhonghua Wei Zhong Bing Ji Jiu Yi Xue. 2013; 25: 749–753. (In Chinese)

[17] Krinsley JS, Fisher M. The diabetes paradox: diabetes is not independently associated with mortality in critically ill patients. Hospital Practice. 2012; 40 :31–35.