Winter-Swimming and Brown Adipose Tissue Activity in Middel-aged Obese Subjects (WinterBAT).

NCT03541096 | Active Not Recruiting

• 1 other identifier: H-18015882 WinterBAT-Study
• Study Type: interventional
• Target: 30
• Locations: 1 country
• Sites: 1

Brief Summary

This study investigates repetitive cold-water exposure on brown fat activity assessed by PET/CT scanning. Furthermore we will assess glucose control upon winter-swimming. Obese prediabetic men and women will be randomized to winter-swimming or control conditions for 4 months.

Conditions

Adipose Tissue, Brown; Brown Adipose Tissue; Uncoupling Protein 1; Cold Exposure; Obesity; Type 2 Diabetes Mellitus; Winter Swimming

Outcome Measures

Primary Outcomes (1)

• Difference between groups in change in brown adipose tissue (BAT) activity during cooling

  BAT activity is measured using positron emission tomography (PET)- Computer tomography (CT) scan. The PET-CT scan uses a glucose-radiotracer (fludeoxyglucose-18 (FDG)) to measure the glucose uptake in BAT, which is associated with BAT activity. FDG is injected following one hour of cooling and the subjects are scanned following one additional hour of cooling. The subjects are continuously cooled throughout the scanning procedure. Difference between groups in change in FDG tracer uptake (post minus pre intervention) during 1,5 hours of cooling is calculated.

  Day 0 (before intervention) and Day 120 (after intervention)

Secondary Outcomes (1)

• Difference between groups in change in glycemic control

  Day 0 (before intervention) and Day 120 (after intervention)

Study Arms (2)

Winter Swimmers

EXPERIMENTAL

4 Months of supervised winter swimming.

Behavioral: Winter Swimming

Control group

PLACEBO COMPARATOR

No winter swimming activities.

Behavioral: Control group

Interventions

Winter Swimming BEHAVIORAL

Supervised Winter Swimming in Copenhagen

Winter Swimmers

Control group BEHAVIORAL

No winter swimming activities.

Control group

Eligibility Criteria

• Age: 40 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Waist circumference above 80 cm for women and 94 cm for men.
• BMI \> 25 but \<40 kg/m2
• Age \> 40 years.
• Low to moderate physical activity level (no physical activity or on average 30 minutes of moderate physical activity per day and not more than 3 hours of training pr. Week)
• Subjects will be included in either one of these cases after the screening:
• Fasting plasma glucose above 5.6 millimol per liter (mmoL/L).
• HbA1C \>39 millimol per mol (mmol/mol).
• hour plasma glucose after a 75 g. oral glucose tolerance test (OGTT) above 7.8 mmol/L.

You may not qualify if:

• Winter swimmer
• Any history of Cancer,
• Clinically significant liver, kidney, heart, inflammatory or lung-disease.
• Pregnancy
• Taking medication (not for hay fever), including glucose-lowering treatment.
• HbA1c \>55 mmol/mol and/or 2-h plasma glucose in the 75-g OGTT \> 15 mmol/L, fasting plasma glucose above 6.9.
• Iron deficiency
• Increased International Normalised Ratio for coagulation (INR).
• Femoral hernia, vene prostheses (pants prosthesis), thrombs in v. Femoralis.
• Abnormal ultrasound echocardiography of the heart found at the health-examination day.
• Contraindications to cold exposure including severe Raynauds disease.
• History of alcohol abuse or use of more than 14 units pr. Week.
• History of drug abuse, including marihuana.
• Smoking including occasional smoking.
• Pacemaker or other electronics implanted in the body.

Sponsors & Collaborators

• Kristian Karstoft: lead

Study Sites (1)

Center for Inflammation and Metabolism/ Center for Physical Activity Research

Copenhagen, 2100, Denmark

Location

MeSH Terms

Conditions

Obesity; Diabetes Mellitus, Type 2

Interventions

Control Groups

Condition Hierarchy (Ancestors)

Overweight; Overnutrition; Nutrition Disorders; Nutritional and Metabolic Diseases; Body Weight; Signs and Symptoms; Pathological Conditions, Signs and Symptoms; Diabetes Mellitus; Glucose Metabolism Disorders; Metabolic Diseases; Endocrine System Diseases

Intervention Hierarchy (Ancestors)

Epidemiologic Research Design; Epidemiologic Methods; Investigative Techniques; Research Design; Methods

Study Officials

• Camilla Schéele, PhD

  Rigshospitalet, Denmark

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: OUTCOMES ASSESSOR
• Purpose: BASIC SCIENCE
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR INVESTIGATOR
• PI Title: MD, PhD, Chief Physician

Study Record Dates

• First Submitted: May 17, 2018
• First Posted: May 30, 2018
• Study Start: November 7, 2018
• Primary Completion: June 1, 2021
• Study Completion: December 31, 2025
• Last Updated: August 17, 2025

Record last verified: 2025-05

Data Sharing

• IPD Sharing: Will not share

Locations

DK (1)