Opinions and practices of blood glucose control in critically ill patients with pre-existing type 2 diabetes in Australian and New Zealand intensive care units

Is it time to personalise glucose targets during critical illness?

PURPOSE OF REVIEW

Dysglycaemia complicates most critical care admissions and is associated with harm, yet glucose targets, particularly in those with preexisting diabetes, remain controversial. This review will summarise advances in the literature regarding personalised glucose targets in the critically ill.

RECENT FINDINGS

Observational data suggest that the degree of chronic hyperglycaemia in critically ill patients with diabetes attenuates the relationship between mortality and several metrics of dysglycaemia, including blood glucose on admission, and mean blood glucose, glycaemic variability and hypoglycaemia in the intensive care unit. The interaction between acute and chronic hyperglycaemia has recently been quantified with novel metrics of relative glycaemia including the glycaemic gap and stress hyperglycaemia ratio. Small pilot studies provided preliminary data that higher blood glucose thresholds in critically ill patients with chronic hyperglycaemia may reduce complications of intravenous insulin therapy as assessed with biomakers. Although personalising glycaemic targets based on preexisting metabolic state is an appealing concept, the recently published CONTROLLING trial did not identify a mortality benefit with individualised glucose targets, and the effect of personalised glucose targets on patient-centred outcomes remains unknown.

SUMMARY

There is inadequate data to support adoption of personalised glucose targets into care of critically ill patients. However, there is a strong rationale empowering future trials utilising such an approach for patients with chronic hyperglycaemia.

Glycemic control in critically ill patients with or without diabetes

Background

Early randomized controlled trials have demonstrated the benefits of tight glucose control. Subsequent NICE-SUGAR study found that tight glucose control increased mortality. The optimal glucose target in diabetic and nondiabetic patients remains unclear. This study aimed to evaluate the relationship between blood glucose levels and outcomes in critically ill patients with or without diabetes.

Methods

This was a retrospective analysis of the eICU database. Repeat ICU stays, ICU stays of less than 2 days, patients transferred from other ICUs, those with less than 2 blood glucose measurements, and those with missing data on hospital mortality were excluded. The primary outcome was hospital mortality. Generalised additive models were used to model relationship between glycemic control and mortality. Models were adjusted for age, APACHE IV scores, body mass index, admission diagnosis, mechanical ventilation, and use of vasopressor or inotropic agents.

Results

There were 52,107 patients in the analysis. Nondiabetes patients exhibited a J-shaped association between time-weighted average glucose and hospital mortality, while this association in diabetes patients was right-shifted and flattened. Using a TWA glucose of 100 mg/dL as the reference value, the adjusted odds ratio (OR) of TWA glucose of 140 mg/dL was 3.05 (95% confidence interval (CI) 3.03–3.08) in nondiabetes and 1.14 (95% CI 1.08–1.20) in diabetes patients. The adjusted OR of TWA glucose of 180 mg/dL were 4.20 (95% CI 4.07–4.33) and 1.49 (1.41–1.57) in patients with no diabetes and patients with diabetes, respectively. The adjusted ORs of TWA glucose of 80 mg/dL compared with 100 mg/dL were 1.74 (95% CI 1.57–1.92) in nondiabetes and 1.36 (95% CI 1.12–1.66) in patients with diabetes. The glucose ranges associated with a below-average risk of mortality were 80–120 mg/dL and 90–150 mg/dL for nondiabetes and diabetes patients, respectively. Hypoglycemia was associated with increased hospital mortality in both groups but to a lesser extent in diabetic patients. Glucose variability was positively associated with hospital mortality in nondiabetics.

Conclusions

Time-weighted average glucose, hypoglycemia, and glucose variability had different impacts on clinical outcomes in patients with and without diabetes. Compared with nondiabetic patients, diabetic patients showed a more blunted response to hypo- and hyperglycemia and glucose variability. Glycemic control strategies should be reconsidered to avoid both hypoglycemia and hyperglycemia.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-022-01769-4.

The Effect of a Liberal Approach to Glucose Control in Critically Ill Patients with Type 2 Diabetes: A multicenter, parallel-group, open-label, randomized clinical trial

Rationale Blood glucose concentrations affect outcomes in critically ill patients but the optimal target blood glucose range in those with type 2 diabetes is unknown. Objective To evaluate the effects of a 'liberal' approach to targeted blood glucose range during intensive care unit (ICU) admission. Methods This mutlicenter, parallel-group, open-label, randomized clinical trial included 419 adult patients with type 2 diabetes expected to be in the ICU on at least three consecutive days. In the intervention group intravenous insulin was commenced at a blood glucose >252 mg/dL and titrated to a target range of 180 to 252 mg/dL. In the comparator group insulin was commenced at a blood glucose >180 mg/dL and titrated to a target range of 108 to 180 mg/dL. The primary outcome was incident hypoglycemia (<72 mg/dL). Secondary outcomes included glucose metrics and clinical outcomes. Main Results At least one episode of hypoglycemia occurred in 10 of 210 (5%) patients assigned the intervention and 38 of 209 (18%) patients assigned the comparator (incident rate ratio: 0.21 (95% CI, 0.09 to 0.49); P<0.001). Those assigned the intervention had greater blood glucose concentrations (daily mean, minimum, maximum), less glucose variability and less relative hypoglycaemia (P<0.001 for all comparisons). By day 90, 62 of 210 (29.5%) in the intervention and 52 of 209 (24.9%) in the comparator group had died (absolute difference 4.6 percentage points (95%CI, -3.9 to 13.2%); P=0.29). Conclusions A liberal approach to blood glucose targets reduced incident hypoglycemia but did not improve patient-centered outcomes. Clinical trial registration available at www.anzctr.org.au, ID: ACTRN12616001135404.

Agreement of blood glucose measured with glucose meter in arterial, central venous, and capillary samples in adult critically ill patients

BACKGROUND

The measurement of blood glucose in critically ill patients is still performed in many ICUs with glucose meters and capillary samples. Several prevalent factors in these patients affect the accuracy of the results and should be interpreted with caution. A weak recommendation from the Surviving Sepsis Campaign (SSC) suggests the use of arterial blood rather than capillary blood for point of care testing using glucose meters.

AIMS AND OBJECTIVES

To analyse the agreement between arterial, central venous, and capillary blood samples of glucose values measured by glucose meter in critically ill patients and study potential confounding factors.

DESIGN

Prospective cross-sectional study in a general intensive care unit (ICU). Patients needing insulin treatment (subcutaneous or intravenous) and blood glucose control were included.

METHODS

Standardized collection of blood samples and measurement of glucose values with a glucometer. Agreement was studied by the Bland-Altman method and stratified analysis of disagreement-survival plots was used to study the influence of haematocrit, pH range, SOFA score, capillary refilling time, intravenous insulin infusion, and lactic acid.

RESULTS

A total of 297 measurements from 54 patients were included. The mean arterial blood glucose was 150.42 (range 31-345 mg/dL). In the graphical analysis, there is a poor agreement both in capillary and venous central to arterial samples, but in opposite direction (underestimation of capillary and overestimation of central venous). Factors associated with a reduction in the agreement between arterial and capillary samples were elevated lactate, poor capillary refilling, and hemodynamic failure. Patients without hemodynamic compromise have an acceptable agreement with values for absolute differences of 16 mg/dL for a disagreement of 10%.

CONCLUSIONS

In critically ill patients, the measurement of blood glucose with a glucose meter should be performed with arterial samples whenever possible. Capillary samples do not accurately estimate arterial blood glucose values in patients with shock and/or vasoactive drugs and underestimate the values in the range of hypoglycemia. Venous samples are subject to error because of potential contamination.

RELEVANCE TO CLINICAL PRACTICE

This study adds support to the recommendation of using arterial blood rather than capillary or venous blood when using glucose meters in critically ill patients, especially in those with hemodynamic failure.

Glycated hemoglobin A1c level on the day of emergency surgery is a marker of premorbid glycemic control: a retrospective observational study

BACKGROUND

Current international guideline recommends to maintain blood glucose level ≤ 180 mg/dL in acute ill patients, irrespective of presence of premorbid diabetes. However, there are studies suggested that optimal acute glycemic control should be adjusted according to premorbid glycemic control in patients with chronic hyperglycemia. Accordingly, to obtain the information of premorbid glycemic control would be relevant. However, the HbA1c level on the day of the emergency operation (HbA1c-ope) might not be useful as a surrogate of premorbid chronic glycemic control, since glucose metabolism can be affected by inflammation, severity of illness and surgical invasion.

METHODS

We hypothesized that HbA1c-ope reflects pre-morbid glycemic control. To assess this hypothesis, we conducted a single-center retrospective observational study to assess the association between HbA1c-ope and HbA1c level measured within 30 days before the operation (HbA1c-pre). We screened patients who had been admitted to the ICU of our hospital after emergency surgery during the period from January 2008 to December 2016. Patients in whom both of HbA1c-ope and HbA1c-pre were measured were included in this study. We compared HbA1c-ope and HbA1c-pre using the paired t-test. The correlation between the two HbA1c measurements was assessed using Pearson's correlation coefficient. Its agreement was assessed using the Bland-Altman approach with 95% confidence intervals.

RESULTS

We included 48 patients in this study. The mean value of HbA1c-pre was 6.3%, which was not significantly different from the mean value of 6.2% for HbA1c-ope (p = 0.12). There was a significant correlation between HbA1c-pre and HbA1c-ope (r2 = 0.70, p < 0.001). The mean difference between two HbA1c measurements was 0.12% (95% CI: -0.03% to 0.27%). The limit of agreement ranged from - 0.9% to +1.1%.

CONCLUSIONS

We found that there was a significant correlation between HbA1c-ope and HbA1c-pre. Our findings suggest that HbA1c-ope can be used to estimate previous glycemic control with an acceptable degree of accuracy, enabling personalized glycemic control in the perioperative period.