Hyperglycemia is a common and potentially serious condition in critically ill patients, often exacerbated by the administration of enteral nutrition (EN). The careful management of blood glucose levels is crucial in an intensive care unit (ICU) setting, where the slightest imbalance can result in significant complications or even mortality. Traditionally, insulin is used to combat elevated blood glucose levels, but a recent study suggests that the use of a low-carbohydrate formula for EN may offer a better solution.

The Study

In a groundbreaking feasibility trial published in Clinical Nutrition ESPEN, researchers investigated the effect of a low carbohydrate formula on glycemic control in enterally-fed adult patients with hyperglycemia in a critical care setting (DOI: 10.1016/j.clnesp.2019.02.013). Led by Ra’eesa Doola from Mater Health Services and The University of Queensland, Australia, the research team conducted a prospective, parallel group, blinded, randomized feasibility trial.

41 patients admitted to the ICU and exclusively receiving EN with two consecutive blood glucose levels greater than 10 mmol/L were enrolled in the study. Patients were randomly assigned to receive either standard enteral nutrition (SE), containing 14.1 g/100 mL of carbohydrates, or an intervention enteral nutrition (IE), with a reduced carbohydrate content of 7.4 g/100 mL. Key outcomes measured included the amount of insulin administered and glycemic variability (coefficient of variation) over the initial 48 hours.

The Findings

The study revealed that using a low carbohydrate formula in enteral nutrition was associated with a reduction in both, the need for administered insulin and glycemic variability, suggesting a potential advancement in the management of hyperglycemia in the critically ill. Timing and overall nutrition are already vastly important in critical care; this study highlights the impact of EN composition on glucose management.

Implications and Future Research

The application of this low carbohydrate formula could raise questions regarding the need for its incorporation into standard ICU protocols. This trial sets the stage for larger-scale investigations to determine the clinical outcomes directly resulting from reduced carbohydrate intake in enteral nutrition among those with hyperglycemia. Further research is required to conclusively determine the benefits observed on a larger scale and with more diverse patient populations.

Discussion

The administration of insulin, while effective at lowering blood glucose levels, can also contribute to significant glycemic variability, which in itself is a risk factor for poor outcomes in critically ill patients. Traditional EN solutions are designed to meet the calorie and nutrient needs but may inadvertently increase the risk of hyperglycemia due to their carbohydrate content. A low carbohydrate EN formula as an alternative potentially alleviates the need for higher doses of insulin and reduces the risk of glucose fluctuations.

Ethical considerations

The trial was conducted with ethical oversight and was registered under the Australian and New Zealand Clinical Trials Registry (ANZCTR number: 12614000166673). All participants or their guardians gave informed consent, and the study adhered to strict privacy and data protection standards.

Conclusion

The study by Doola et al. marks significant progress in understanding the effect of carbohydrate content in enteral nutrition on glycemic control in the ICU. While the results are promising, the push for this formulation to be applied in clinical practice would require validation through larger, multicenter trials. The goal remains to offer the best patient care with the least risk of complications, and this study paves the way for further advancements in critical care nutrition therapy.

Keywords

1. Low Carbohydrate Enteral Nutrition
2. ICU Glycemic Control
3. Critical Care Hyperglycemia Management
4. Insulin Administration in ICU
5. Enteral Nutrition Trials

References

1. Doola, R., Deane, A. M., Tolcher, D. M., Presneill, J. J., Barrett, H. L., Forbes, J. M., … & Sturgess, D. J. (2019). The effect of a low carbohydrate formula on glycaemia in critically ill enterally-fed adult patients with hyperglycaemia: A blinded randomised feasibility trial. Clinical Nutrition ESPEN, 31, 80-87. https://doi.org/10.1016/j.clnesp.2019.02.013
2. McCowen, K. C., Malhotra, A., & Bistrian, B. R. (2001). Stress-induced hyperglycemia. Critical Care Clinics, 17(1), 107-124. doi:10.1016/s0749-0704(05)70154-1
3. Van den Berghe, G., Wouters, P., Weekers, F., et al. (2001). Intensive insulin therapy in critically ill patients. The New England Journal of Medicine, 345(19), 1359-1367. doi:10.1056/NEJMoa011300
4. Singer, P., et al. (2019). ESPEN guideline on clinical nutrition in the intensive care unit. Clinical Nutrition, 38(1), 48-79. https://doi.org/10.1016/j.clnu.2018.08.037
5. American Diabetes Association. (2020). Standards of Medical Care in Diabetes—2020. Diabetes Care, 43(Supplement 1), S1. DOI: 10.2337/dc20-Sint