Glycemic control in burn patients

Overview

Hyperglycemia is a hallmark of the systemic response to major burn injury, driven by massive catecholamine release, cortisol elevation, glucagon excess, and peripheral insulin resistance. This stress hyperglycemia is distinct from diabetes-related hyperglycemia and occurs even in patients without pre-existing glucose dysregulation. In burns, the hypermetabolic response is the most extreme seen in any injury pattern. Insulin resistance peaks between 7 and 14 days post-injury and can persist for years, confirmed by HOMA2 and QUICKI measurements in burned adults ^[7]. Persistent hyperglycemia after burns is associated with increased rates of infection, sepsis, graft loss, and mortality. Managing blood glucose in the burn ICU requires balancing the documented harms of hyperglycemia against the significant risk of iatrogenic hypoglycemia.

Patients with pre-existing diabetes face compounded risk. Diabetic burn patients have increased morbidity and longer ICU stays compared to non-diabetics with similar injuries ^[8]. This makes glycemic management in the burn ICU a two-population problem: stress hyperglycemia in previously healthy patients and decompensated control in established diabetics.

Foundational Critical Care Evidence

Two landmark trials frame the glycemic control debate across all ICU populations, and understanding both is essential before addressing what makes burns different.

Van den Berghe and colleagues randomized 1,548 surgical ICU patients to intensive insulin therapy (target 80-110 mg/dL) versus conventional management (target 180-200 mg/dL) ^[1]. Intensive control reduced ICU mortality from 8.0% to 4.6% (P<0.04), bloodstream infections by 46%, and acute renal failure by 41% ^[1]. This trial changed practice worldwide. For nearly a decade, ICUs everywhere adopted tight glucose targets.

Then NICE-SUGAR enrolled 6,104 patients across 42 centers and asked the same question in a broader, mixed medical-surgical ICU population ^[2]. Intensive control (target 81-108 mg/dL) increased 90-day mortality compared to conventional control (target 144-180 mg/dL): 27.5% versus 24.9% (OR 1.14, P=0.02) ^[2]. Severe hypoglycemia occurred in 6.8% of the intensive group versus 0.5% of controls ^[2]. The pendulum swung back hard.

Burns sit between these two populations in a clinically important way. Burn patients are surgical ICU patients with prolonged stays, which is the population Van den Berghe studied and found benefit in. But the magnitude of the hypermetabolic response creates insulin resistance far beyond what general surgical patients experience. Achieving tight targets requires aggressive insulin dosing, which amplifies hypoglycemia risk. Neither trial enrolled enough burn patients to answer the question for this population specifically.

Evidence for Glycemic Control in Burns

The evidence on optimal glucose targets in burns parallels the broader critical care debate but with important distinctions. Burn patients generate the most extreme hypermetabolic response in medicine, with catecholamine levels, resting energy expenditure, and protein catabolism that dwarf other trauma populations. This metabolic storm drives hyperglycemia that is harder to control and more consequential when left uncontrolled.

A narrative review of glucose management in the burn ICU identified eight studies meeting inclusion criteria from 2,154 screened articles ^[3]. Two studies reported mortality benefit of intensive glucose control (target less than 110 mg/dL) compared to conventional management (target less than 150 mg/dL), while two studies showed no mortality difference ^[3]. Three studies reported reduced infectious complications including pneumonia, urinary tract infection, sepsis, and bacteremia with intensive control ^[3]. However, six of eight studies reported higher risk for hypoglycemia with tight glucose control ^[3]. The review recommended an individualized patient-centered approach factoring comorbidities, burn injury characteristics, and risk factors ^[3].

Current Consensus Practice

No large multicenter randomized trial has addressed glycemic targets in a burn-specific population. In the absence of that evidence, most burn centers have settled on a practical middle ground: target glucose below 150 mg/dL rather than below 110 mg/dL. This reflects the post-NICE-SUGAR recalibration, modulated by the recognition that burn patients' extreme insulin resistance makes tight control both more beneficial (if achieved without hypoglycemia) and more dangerous (each unit of insulin carries more risk when the patient's glucose is swinging between 40 and 400). The debate remains unresolved specifically in burns because the same pathophysiology that makes hyperglycemia so damaging also makes its treatment so hazardous.

Insulin Therapy

Continuous insulin infusion (CII) remains the standard approach for glycemic control in critically ill burn patients. A burn center quality improvement initiative developed a response-based CII algorithm designed to adjust dosage based on glycemic response ^[6]. Post-implementation, hypoglycemia rates decreased significantly (0.6% to 0.2%, p less than 0.001) while maintaining equivalent median blood glucose (149.9 vs 146.5 mg/dL) and time within goal glycemic range (13.8 vs 14.7 hours/day) ^[6].

Practical guidance for glycemic management in surgical patients, including burn patients, emphasizes the importance of avoiding hypoglycemia, utilizing CII protocols for critically ill patients, and ensuring adequate glucose monitoring with point-of-care testing ^[9].

Metformin as Alternative

Mechanistic Rationale

Metformin has emerged as a potential therapeutic agent for post-burn hyperglycemia with pleiotropic effects extending beyond glycemic control. These include attenuation of muscle catabolism, suppression of lipolysis, regulation of non-shivering thermogenesis (reducing the hypermetabolic drive to browning of white adipose tissue), support of mitochondrial and immune function, enhanced wound healing, and potential mitigation of burn-induced acceleration of biological aging ^[4].

Clinical Outcomes

A retrospective study using the TriNetX database compared burned patients receiving insulin alone, metformin alone, or both within one week of injury ^[5]. After propensity score matching, the insulin cohort was at significantly increased risk for hyperglycemia, hypoglycemia, sepsis, lactic acidosis, and death compared to the metformin cohort (all p less than 0.0001) ^[5]. The combination of insulin and metformin was no more effective in reducing hyperglycemia and hypoglycemia than insulin alone but was less effective than metformin alone ^[5]. These data suggest metformin monotherapy may represent a paradigm shift in post-burn glycemic management, though the retrospective design and potential for confounding by indication warrant prospective validation.

Subphenotype-Directed Therapy

Transcriptomic analysis of the HALF-PINT trial demonstrated that children with a hyperinflammatory subphenotype benefited from tight glycemic control (target 80-110 mg/dL), experiencing greater reductions in inflammatory cytokines, innate immune gene expression, and heme metabolism gene expression ^[10]. Causal mediation testing indicated that these changes partly explained the observed mortality benefit. This finding suggests that precision approaches to glycemic targets based on inflammatory subphenotype may optimize outcomes rather than applying uniform targets to all patients ^[10].

Controversies and Evidence Gaps

The optimal blood glucose target for burn patients remains debated: targets below 110 mg/dL reduce infections but increase hypoglycemia, while targets below 150 mg/dL may be safer but less effective. No large multicenter randomized trial has addressed this question in a burn-specific population. The role of metformin requires prospective validation; concerns about lactic acidosis in patients with renal insufficiency, hepatic dysfunction, or hemodynamic instability limit its applicability in the most severely ill patients. Whether continuous glucose monitoring (CGM) technology can improve glycemic control and reduce hypoglycemia in the burn ICU is an active area of investigation. The interaction between enteral nutrition (often administered continuously in burn patients) and glycemic management protocols needs further study.

References

[1] Van den Berghe G et al. "Intensive insulin therapy in critically ill patients." N Engl J Med 2001;345(19):1359-1367. PMID: 11794168 [2] NICE-SUGAR Study Investigators. "Intensive versus conventional glucose control in critically ill patients." N Engl J Med 2009;360(13):1283-1297. PMID: 19318384 [3] Won P et al. "Blood glucose control in the burn intensive care unit: A narrative review of literature." Burns 2023;49(8):1788-1795. PMID: 37385891 [4] Khalaf F et al. "Beyond diabetes: harnessing the power of metformin in burn care." Crit Care 2025;29(1):423. PMID: 41057939 [5] Hallman TG et al. "Metformin is associated with reduced risk of mortality and morbidity in burn patients compared to insulin." Burns 2024;50(7):1779-1789. PMID: 38981799 [6] Hendrix HA et al. "Simplified Approach to Incorporating Glycemic Response Within a Continuous Insulin Infusion Algorithm to Improve the Incidence of Hypoglycemia in a Single Burn Center." J Burn Care Res 2020;41(4):791-795. PMID: 32249298 [7] Jeschke MG, Stanojcic M. "Pathophysiological Response to Burns in Adults." Ann Surg 2018;267(3):576-584. PMID: 29408836 [8] Dolp R, Jeschke MG. "Impact of diabetes on outcomes of burn patients." Crit Care 2019;23(1):41. PMID: 30691499 [9] Ware LR et al. "Practical approach to clinical controversies in glycemic control for hospitalized surgical patients." Nutr Clin Pract 2022;37(3):521-535. PMID: 35490289 [10] Zinter MS et al. "Biologic Mechanisms Underlying the Heterogeneous Response to Tight Glycemic Control among Differentially Inflamed Patients in the HALF-PINT Trial." Am J Respir Crit Care Med 2025;211(8):1463-1473. PMID: 40493436