Is delaying nutrition safe for patients in intensive care?

ISRCTN	ISRCTN16339579
DOI	https://doi.org/10.1186/ISRCTN16339579
Sponsor	University of Tartu
Funder	Eesti Teadusagentuur

Submission date: 23/01/2026
Registration date: 28/01/2026
Last edited: 28/01/2026

Recruitment status: Not yet recruiting
Overall study status: Ongoing
Condition category: Nutritional, Metabolic, Endocrine

Prospectively registered

Protocol

Statistical analysis plan

Results

Individual participant data

Record updated in last year

Plain English summary of protocol

Plain English summary of protocol not provided at time of registration

Contact information

Dr Kadri Tamme
Scientific, Public, Principal investigator

Institute of Clinical Medicine, University of Tartu
L. Puusepa 8
Tartu
50406
Estonia

ORCID ID	0000-0001-6110-0417
Phone	+3727318414
Email	kadri.tamme@ut.ee

Dr Martin Sundström Rehal
Public, Scientific, Principal investigator

Perioperative Medicine and Intensive Care K32
Karolinska University Hospital Huddinge
Hälsovägen 13
Stockholm
14186
Sweden

ORCID ID	0000-0003-3387-6191
Phone	+46 0737164623
Email	martin.sundstrom-rehal@regionstockholm.se

Study information

Primary study design	Interventional
Allocation	Randomized controlled trial
Masking	Open (masking not used)
Control	Active
Assignment	Crossover
Purpose	Treatment
Scientific title	Feasibility And Safety of delaying nuTrition in Intensive Care Units (FAST-ICU) — a multicentre, cluster-randomised cross-over trial
Study acronym	FAST-ICU
Study objectives	Primary Objective Assess the feasibility and safety with regards to hypoglycemia of withholding nutrition and glucose-containing maintenance solutions during the first 72 hours of ICU stay. Secondary Objectives • Compare ICU and hospital mortality. • Compare ICU and hospital length of stay. • Evaluate effects on: o glycaemia, insulin need o occurrence of moderate hypernatremia o occurrence of refeeding syndrome (RFS), defined as drop of serum phosphate with or without hypokalemia and hypomagnesemia, o need for organ support therapy (invasive/non-invasive mechanical ventilation, vasopressors, RRT, mechanical circulatory support)
Ethics approval(s)	Approved 05/12/2025, Research Ethics Committee of the University of Tartu (UT REC) (University of Tartu, Grant Office, Raekoja plats 9, Tartu, 51004, Estonia; +372 737 6215; eetikakomitee@ut.ee), ref: 406/T-33
Health condition(s) or problem(s) studied	Delaying early (first 72 hours) feeding and glucose-containing maintenance solutions in intensive care patients.
Intervention	Multicentre, open-label cluster-randomised crossover trial with ICU clusters. Each ICU is randomised to one of two sequences: AB (Intervention → Control) or BA (Control → Intervention). The method of randomisation will be by a computer program (RedCap randomisation module). There will be a 2- to 4-week wash-out/training phase between periods 1 and 2. Intervention Policy (A): Withhold nutrition and glucose solutions (First 72 h) • No enteral nutrition (EN) and no parenteral nutrition (PN) for the first 72 hours from ICU admission time (t=0). • No glucose-containing maintenance IV solutions during the first 72 hours. Balanced crystalloids or normal saline permitted per clinical need. • 5% glucose solution permitted as vehicle for IV medications as necessary (according to local standard), or as treatment for hypernatremia • Oral intake permitted ad lib if the patient is awake, willing and able to eat safely. • Micronutrients: daily vitamins and trace elements are allowed per local practice. • Protein supplements are not allowed unless part of the standard oral diet. • Arterial or venous blood glucose measurement every 4h. • Rescue glucose will be administered according to local protocol. • After 72 hours, feeding transitions to usual care at clinician discretion (including EN/PN initiation and caloric/protein targets). Control Policy (B): Standard of Care • Initiation and advancement of EN/PN and use of glucose-containing maintenance fluids per local practice from admission. • Arterial or venous blood glucose measurement every 4h. • Insulin and glycaemic control per local protocols.
Intervention type	Mixed
Primary outcome measure(s)	Proportion of patients with ≥1 hypoglycemic episode (blood glucose <3.9 mmol/L) within 72 hours measured using data collected from patient medical records at 72 hours after ICU admission
Key secondary outcome measure(s)	ICU mortality measured using data collected from patient medical records at ICU discharge, censored at 90 days Hospital mortality measured using data collected from patient medical records at hospital discharge, censored at 90 days Proportion of patients with severe hypoglycemia (<3.0 mmol/L) measured using data collected from patient medical records at 7 days after ICU admission Daily need for organ support therapies measured using data collected from patient medical records at a daily time point for 7 days after ICU admission Proportion of patients with moderate hypernatremia (> 150 mmol/L) measured using data collected from patient medical records at 7 days after ICU admission Proportion of patients with refeeding hypophosphatemia (phosphate < 0.65 mmol/l and a drop of > 0.16 mmol/l after initiation of feeding) at 7 days measured using using data collected from patient medical records at 7 days after ICU admission
Completion date	30/12/2027

Eligibility

Participant type(s)
Age group	Mixed
Lower age limit	18 Years
Upper age limit	100 Years
Sex	All
Target sample size at registration	2160
Key inclusion criteria	1. Adult (≥18 years) 2. Intensive Care Unit (ICU) admission (index admission to the participating ICU)
Key exclusion criteria	1. The patient requires intravenous glucose infusion according to the attending clinician’s assessment 2. Acute or acute-on-chronic liver failure 3. Moderate hypernatremia ( >150 mmol/L) 4. Diabetic ketoacidosis or hyperosmolar hyperglycemic state at admission 5. Pregnancy 6. Exclusive end-of-life care (no other treatment goal than comfort care for end of life) 7. Organ donor 8. Prior enrolment in this trial during the same hospitalisation 9. Patients with a metabolic disease requiring specific diet and patients with clinical need for a ketogenic diet 10. Patients already enrolled in other interventional studies on nutrition, intravenous fluids, phosphate supplementation or hormonal therapies that influence glucose homeostasis
Date of first enrolment	16/03/2026
Date of final enrolment	31/12/2026

Locations

Countries of recruitment

Austria
Belgium
Estonia
Germany
Netherlands
New Zealand
Saudi Arabia
Sweden
Switzerland
United States of America

Study participating centres

Results and Publications

Individual participant data (IPD) Intention to share	No
IPD sharing plan summary	Not expected to be made available
IPD sharing plan

Editorial Notes

28/01/2026: Study’s existence confirmed by the Research Ethics Committee of the University of Tartu (UT REC), Estonia.