Acute and Chronic Glucose Control in Critically Ill Patients With Diabetes: The Impact of Prior Insulin Treatment

The occurrence of Hospital-Acquired Pneumonia is independently associated with elevated Stress Hyperglycaemia Ratio at admission but not elevated blood glucose

BACKGROUND

The association between stress-induced hyperglycaemia (SIH) and increased infection rates in hospitalised subjects is well-known. It is less clear if SIH at admission independently drives new-onset infections. We assessed the relationship between early exposure at admission to both the Stress Hyperglycaemia Ratio (SHR) and Blood Glucose (BG) with Hospital-Acquired Pneumonia (HAP).

METHODS

This observational retrospective study included those with length-of-stay > 1 day, BG within 24 h of admission and recent haemoglobin A1c. SIH was defined as BG ≥ 10 mmol/L, or SHR ≥ 1.1, measured at both admission and as a 24-hour maximum. Multivariable analyses were adjusted for length-of-stay, age, mechanical ventilation, and chronic respiratory disease.

RESULTS

Of 5,339 eligible subjects, 110 (2.1%) experienced HAP. Admission SHR ≥ 1.1 was independently associated with HAP (OR 3.04, 95% CI 1.98-4.68, p < 0.0001) but not BG ≥ 10 mmol/L (OR 0.65, 95% CI 0.41-1.03, p = 0.0675). The association with SHR strengthened using maximum 24-hour values (OR 3.37, 95% CI 2.05-5.52, p < 0.0001) while BG ≥ 10 mmol/L remained insignificant (OR 0.96, 95% CI 0.63-1.46, p = 0.86). Of those experiencing HAP 40 (36.4%) occurred in subjects with no recorded BG ≥ 10 mmol/L but SHR ≥ 1.1.

CONCLUSION

SIH at admission defined as SHR ≥ 1.1, but not the conventional marker of BG ≥ 10 mmol/L, was independently associated with the subsequent onset of HAP, commonly at BG < 10 mmol/L.

Malglycemia in the critical care setting. Part I: Defining hyperglycemia in the critical care setting using the glycemic ratio

INTRODUCTION

Stress-induced hyperglycemia (SIH) is conventionally represented by Blood Glucose (BG) although recent evidence indicates the Glycemic Ratio (GR, quotient of mean BG and estimated preadmission BG) is a superior prognostic marker. We assessed the association between in-hospital mortality and SIH, using BG and GR in an adult medical-surgical ICU.

METHODS

We included patients with hemoglobin A1c (HbA1c) and minimum four BGs in a retrospective cohort investigation (n = 4790).

RESULTS

A critical SIH threshold of GR 1.1 was identified. Mortality increased with increasing exposure to GR ≥ 1.1 (r² = 0.94, p = 0.0007). Duration of exposure to BG ≥ 180 mg/dL demonstrated a less robust association with mortality (r² = 0.75, p = 0.059). In risk-adjusted analyses, hours GR ≥ 1.1 (OR 1.0014, 95%CI (1.0003-1.0026), p = 0.0161) and hours BG ≥ 180 mg/dL (OR 1.0080, 95%CI (1.0034-1.0126), p = 0.0006) were associated with mortality. In the cohort with no exposure to hypoglycemia however, only hours GR ≥ 1.1 was associated with mortality (OR 1.0027, 95%CI (1.0012-1.0043), p = 0.0007), not BG ≥ 180 mg/dL (OR 1.0031, 95%CI (0.9949-1.0114), p = 0.50) and this relationship remained intact for those who never experienced BG outside the 70-180 mg/dL range (n = 2494).

CONCLUSIONS

Clinically significant SIH commenced above GR 1.1. Mortality was associated with hours of exposure to GR ≥ 1.1 which was a superior marker of SIH compared to BG.

Case-control Investigation of Previously Undiagnosed Diabetes in the Critically Ill

Context

The outcome of patients requiring intensive care can be influenced by the presence of previously undiagnosed diabetes (undiagDM).

Objective

This work aimed to define the clinical characteristics, glucose control metrics, and outcomes of patients admitted to the intensive care unit (ICU) with undiagDM, and compare these to patients with known DM (DM).

Methods

This case-control investigation compared undiagDM (glycated hemoglobin A1c [HbA1c] ≥ 6.5%, no history of diabetes) to patients with DM. Glycemic ratio (GR) was calculated as the quotient of mean ICU blood glucose (BG) and estimated preadmission glycemia, based on HbA1c ([28.7 × HbA1c] - 46.7 mg/dL). GR was analyzed by bands: less than 0.7, 0.7 to less than or equal to 0.9, 0.9 to less than 1.1, and greater than or equal to 1.1. Risk-adjusted mortality was represented by the Observed:Expected mortality ratio (OEMR), calculated as the quotient of observed mortality and mortality predicted by the severity of illness (APACHE IV prediction of mortality).

Results

Of 5567 patients 294 (5.3%) were undiagDM. UndiagDM had lower ICU mean BG (P < .0001) and coefficient of variation (P < .0001) but similar rates of hypoglycemia (P = .08). Mortality and risk-adjusted mortality were similar in patients with GR less than 1.1 comparing undiagDM and DM. However, for patients with GR greater than or equal to 1.1, mortality (38.5% vs 10.3% [P = .0072]) and risk-adjusted mortality (OEMR 1.18 vs 0.52 [P < .0001]) were higher in undiagDM than in DM.

Conclusion

These data suggest that DM patients may develop tolerance to hyperglycemia that occurs during critical illness, a protective mechanism not observed in undiagDM, for whom hyperglycemia remains strongly associated with higher risk of mortality. These results may shed light on the natural history of diabetes.

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.

Insulin therapy associated relative hypoglycemia during critical illness

PURPOSE

In critically ill diabetes patients, relative hypoglycemia (RH) (a decrease in glucose ≥30% below pre-admission levels, as estimated by HbA1c) is associated with greater mortality and absolute hypoglycemia. We investigated the epidemiology and outcomes of RH when it was associated with insulin therapy.

METHODS

We performed retrospective analysis of a cohort of critically ill patients with diabetes who received insulin in the intensive care units (ICUs) of a tertiary hospital. The primary outcome was 28-day mortality with respect to insulin therapy associated relative hypoglycemia (ITARH).

RESULTS

ITARH occurred in 184 (42%) of insulin-treated patients. ITARH was associated with a higher HbA1c (8.6% vs 6.6%, p < 0.001), a higher glycemic variability index (121 vs 75.1 mmol²/L²/h/week, p < 0.001) and more absolute hypoglycemia (18.5% vs 3.94%, p < 0.001). Its frequency peaked about 5 h after initiation of insulin therapy. ITARH was associated with a greater risk of subsequent hypoglycemia (adjusted HR 3.5, 95% CI 1.7-6.8) but not mortality (HR 1.2, 95% CI 0.7-2.2).

CONCLUSIONS

ITARH is common in insulin treated critically ill diabetes patients and associated with poorer glycemic control. Unlike reports of RH in general, it is not associated with mortality, suggesting that the prognostic implications of RH differ according to its context.

Nutritional therapy in critically ill patients with diabetes

PURPOSE OF REVIEW

There has been a significant increase in nutrition therapy related studies within the critical care cohort in recent years. Management of patients with both diabetes and stress hyperglycaemia through targeted nutrition interventions is no exception. The aim of this review is to outline current available diabetes specific nutrition formula, its impact on gastric emptying and subsequently glycaemic control as well as explore recent literature on the efficacy of utilizing nutrition support to optimize glycaemic control in critically ill patients.

RECENT FINDINGS

Studies explored within this review were similar in terms of outcomes measures, focusing primarily on insulin use and glycaemic control. Although there were promising results in terms of the impact of diabetes-specific nutrition formula on these outcome measures, there were no significant associations with clinical outcomes.

SUMMARY

The use of diabetes-specific formulae in critically ill patients with pre-existing diabetes and stress hyperglycaemia can be considered a logical approach to minimize the risks associated with high doses of insulin. Additional research is required to address the effects of these formulae on the dysglycaemia, nursing workload, safety of glycaemic control and cost-effectiveness.

Relative Hypoglycemia and Lower Hemoglobin A1c-Adjusted Time in Band Are Strongly Associated With Increased Mortality in Critically Ill Patients

OBJECTIVES

To determine the associations of relative hypoglycemia and hemoglobin A1c-adjusted time in blood glucose (BG) band (HA-TIB) with mortality in critically ill patients.

DESIGN

Retrospective cohort investigation.

SETTING

University-affiliated adult medical-surgical ICU.

PATIENTS

Three thousand six hundred fifty-five patients with at least four BG tests and hemoglobin A1c (HbA1c) level admitted between September 14, 2014, and November 30, 2019.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patients were stratified for HbA1c bands of <6.5%; 6.5-7.9%; greater than or equal to 8.0% with optimal affiliated glucose target ranges of 70-140, 140-180, and 180-250 mg/dL, respectively. HA-TIB, a new glycemic metric, defined the HbA1c-adjusted time in band. Relative hypoglycemia was defined as BG 70-110 mg/dL for patients with HbA1c ≥ 8.0%. Further stratification included diabetes status-no diabetes (NO-DM, n = 2,616) and preadmission treatment with or without insulin (DM-INS, n = 352; DM-No-INS, n = 687, respectively). Severity-adjusted mortality was calculated as the observed:expected mortality ratio (O:EMR), using the Acute Physiology and Chronic Health Evaluation IV prediction of mortality. Among NO-DM, mortality and O:EMR, decreased with higher TIB 70-140 mg/dL (p < 0.0001) and were lowest with TIB 90-100%. O:EMR was lower for HA-TIB greater than or equal to 50% than less than 50% and among all DM-No-INS but for DM-INS only those with HbA1 greater than or equal to 8.0%.Among all patients with hba1c greater than or equal to 8.0% And no bg less than 70 mg/dl, mortality was 18.0% For patients with relative hypoglycemia (bg, 70-110 mg/dl) (p < 0.0001) And was 0.0%, 12.9%, 13.0%, And 34.8% For patients with 0, 0.1-2.9, 3.0-11.9, And greater than or equal to 12.0 Hours of relative hypoglycemia (p < 0.0001).

CONCLUSIONS

These findings have considerable bearing on interpretation of previous trials of intensive insulin therapy in the critically ill. Moreover, they suggest that BG values in the 70-110 range may be deleterious for patients with HbA1c greater than or equal to 8.0% and that the appropriate target for BG should be individualized to HbA1c levels. These conclusions need to be tested in randomized trials.