Low‐carbohydrate, high‐fat enteral formulas for managing glycemic control in patients who are critically ill: A review of the evidence

Abstract

Hyperglycemia is associated with increased morbidity and mortality. Lowcarbohydrate, high-fat (LCHF) enteral formulas are marketed to improve glycemic control; however, given the multifactorial mechanisms contributing to hyperglycemia in patients who are critically ill, the effect that LCHF formulas may have on improving glycemic control in this patient population is unclear. Current guidelines for the use of LCHF formulas among patients who are critically ill are limited by a lack of evidence. This review explores recent research published in the past 7 years to determine whether LCHF enteral formulas improve glycemic control compared with standard enteral formulas in patients who are critically ill. Four randomized controlled trials met the inclusion criteria for this review. Their results suggest that LCHF formulas may improve glycemic control in patients who are critically ill with diabetes mellitus and/or who are hyperglycemic. Further large-scale randomized controlled trials are warranted to validate these findings among different subgroups of patients with critical illness. The potential benefits of LCHF formulas need to be weighed against specific limitations, including that LCHF formulas typically do not contain sufficient protein to meet the recommended needs of patients who are critically ill. K E Y W O R D Scritical illness, enteral nutrition, hyperglycemia, low-carbohydrate diet INTRODUCTION/BACKGROUNDThe American Diabetes Association (ADA) defines hyperglycemia in hospitalized patients as a blood glucose level of >140 mg/dl. 1 Hyperglycemia is associated with increased morbidity and mortality and is widely prevalent among patients who are critically ill. 2 Large retrospective studies of patients in intensive care units (ICUs) have cited prevalence rates ranging from 32% to 46%. 3,4

Enteral nutrition product formulations: A review of available products and indications for use

“…Findings of the review showed LCHF formulas may improve glycemic control in patients who are critically ill with diabetes mellitus and/or hyperglycemic patients. Larger randomized trials are needed to validate these finding among different subgroups of patients with critical illness 23 …”

“…Fiber is also increased with a blend of soluble, insoluble fiber and prebiotics over standard enteral formulations. 23,24 A randomized, controlled, double-annonymized, crossover study conducted by Lansink et al 22 in 23 ambulant nonhospitalized participants with type 2 diabetes for >6 months compared participants receiving a diabetesspecific high-energy, high-protein, low-carbohydrate formula containing a low-glycemic index carbohydrate to an isocaloric, fiber-containing standard formula. Participants received EN via nasogastric feeding tube for 4 h after an overnight fast of 10 h. To meet eligibility criteria the participants had to be on a controlled antihyperglycemic regimen with metformin and/or sulfonylureas for at least 2 months and expected to continue on current regimen throughout the duration of the study.…”

“…The intervention included an LCHF formula defined as a formula containing ≤40% of calories from carbohydrate and ≥40% of calories from fat. All four randomized controlled trials included had similar macronutrient distribution and fiber content, but they all chose a different method to measure glycemic variability 23 . The review acknowledged all four trials had comparable admission diagnosis and the LCHF formulas used had similar macronutrient distributions.…”

Enteral Nutrition Overview

“…Further, the methodology of some research has been called into question [ 27 ] and the heterogeneity of studies have also made it difficult to draw conclusions [ 28 ]. In a recent review, the authors concluded that there was insufficient evidence to promote the use of low carbohydrate formulas [ 29 ]. Long-term use of these formulas has also not been sufficiently studied; therefore, potential long-term side effects or complications are unknown.…”

“…These formulas should be avoided in patients with delayed gastric emptying, fat malabsorption, or other conditions in which high fat intake is not recommended. They should also be avoided in some critically ill patients, namely those that are at risk for bowel ischemia or obstruction in which fiber intake is contraindicated [ 29 ].…”