An interventional study of Winter Swimming and Control group in Adipose Tissue, Brown, Brown Adipose Tissue and Uncoupling Protein 1, sponsored by Kristian Karstoft. Active, not recruiting at 1 site in Denmark. Open to participants aged 40 Years and older. Per ClinicalTrials.gov, last updated 2025-08-17.
Sponsored by Kristian Karstoft · Not applicable, Interventional, and Basic science
Among 350 studies in Obesity with a site in Denmark — 58 open to participants now, 84 under way, 23 of them phase 3. Obesity · Denmark.
Among the 350 studies in Obesity with a site in Denmark, this one is the 196th largest by enrollment of the 282 interventional ones that give a count, is one of 12 that started in 2018, is one of 187 with no phase, reaches primary completion later than 2 of the 83 other live ones, and was the 189th registered.
11,529 studies on the registry are indexed under Obesity; 2,035 are open to participants now.
Browse Obesity studies →58 of the 350 studies in Obesity with a site in Denmark are open now. Recruiting first, the newest first:
University Hospital, Gentofte, Copenhagen · Sites in Denmark
Ages 20–40 · Men only · Healthy volunteers
University of Copenhagen · Sites in Denmark
Ages 18–75 · Healthy volunteers
Signe Torekov · Sites in Denmark
Ages 5+ · Healthy volunteers
AstraZeneca · Sites in Denmark, United States, Argentina and 8 more countries
Ages 18+
Novo Nordisk A/S · Sites in Denmark, United States, Belgium and 7 more countries
Ages 18+
A study can be open while its sites in Denmark have not opened yet or have stopped. Only those recruiting at a site in Denmark →
Of the 1,336 Obesity studies recruiting now, 377 (28%) set no upper age limit and 856 (64%) stop at 75 or younger; 166 take children under 18; 488 take healthy volunteers.
This study: 40 Years and older · all sexes · no healthy volunteers.
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350 studies; the count open now beside each. This study's row is marked.
A study in two phases is counted once above. Listed by phase, each with its combined phases: Phase 1 15 · Phase 2 25 · Phase 3 42 · Phase 4 18
First in 1983; this study’s year is marked. 12 started in 2018.
By drug class, each counting the studies that test any of its medicines:
This study's enrollment of 30 is below the median of 67 across 9,010 interventional studies indexed under Obesity.
Median enrollment 71 across the 282 interventional studies, 93 across the 68 observational. Of the 233 that completed or were terminated, 14 (6%) have results posted.
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65 of 350 have an industry lead sponsor. The 10 most frequent:
Kristian Karstoft is the lead sponsor of 4 studies on the registry; none are open to participants now.
Kristian Karstoft has 1 study filed under Obesity — fewer than ten, so there is no comparison to draw.
14 of the studies in Obesity with a site in Denmark that are under way reach primary completion within a year, 2 of them phase 3. Phase 3 first, then by date:
| Study | Primary completion |
|---|---|
| NCT06914895Phase 3Eli Lilly and CompanyA Study of Tirzepatide (LY3298176) Compared With Placebo in Adults With Type 1 Diabetes and Obesity or Overweight | 2026-11 |
| NCT06858839Phase 3AmgenEvaluation of Maridebart Cafraglutide in Adult Participants Without Type 2 Diabetes Mellitus Who Have Obesity or Are Overweight | 2027-01-21 |
| NCT06833749KeyBioscience AGEfficacy and Safety of KBP-336 in Obese Individuals with Osteoarthritis | 2026-11 |
| NCT07463495University of AarhusThe Metabolic Effects of Oral Tributyrin Administration | 2026-12 |
| NCT06624462Bjorn H. EbdrupEffectiveness of a Pragmatic, Metabolic Care Clinic for Patients With Severe Mental Illness - The Meta Care Clinic | 2026-12 |
Add all 14 to your calendar (.ics) → With an account.
Among the 350 studies in Obesity with a site in Denmark, from their registry updates:
This tab as a report to print or save as PDF → With an account.
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.
Brown fat (BAT) is an energy-consuming tissue. Long-term activation of BAT in adults increases clearance of blood glucose and non-esterified fatty acids (NEFA), insulin sensitivity and metabolic rate. Moreover, adipokines released from BAT, known as batokines, represent a promising but currently unexplored area in terms of metabolic regulation. Cooling activates BAT; however, current cooling protocols fail to activate BAT in a large part of the population. Whether this failure in activation is related to biology, inefficient detection or cooling protocols is unknown. With our initial acute cooling study (protocol number: H-16038581), these protocols have successfully been optimized whereupon novel batokines will be identified. Having established a methodology for assessing BAT activity and batokine profiles, a longer-term cooling intervention (winter swimming) will be performed to examine the effect of repetitive cold-water exposure on BAT activity. Obese pre-diabetic subjects will be included in a 4-month supervised winter swimming (WS) intervention.
It is hypothesized, that repetitive cold-water exposure constituted by WS, increase BAT activation and volume, followed by improved glycemic control in obese pre-diabetic subjects.
Method The study is a randomized controlled, parallel-group intervention study. The investigator will recruit 30 obese pre-diabetic non-winter-swimmers to participate in a WS intervention group (n=15) or control group (n=15) with no WS activities. Subjects will either be randomized to the WS group, who will winter-swim 4 months, 2-3 times/week including sauna-visits if desired, or control conditions with no WS during the 4 months (October to May).
Main aims
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Subjects will be included in either one of these cases after the screening:
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
A blood test of average blood sugar over the past two to three months, given as a percentage or in mmol/mol. 6.5% (48 mmol/mol) or more is the usual threshold for diabetes, normally confirmed by a second test.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Blood tests of how long blood takes to clot. The INR is the prothrombin time (PT) put on a common scale; about 1 is usual for someone not taking a blood thinner.
Criteria often make an exception for people on a blood thinner such as warfarin, whose INR is raised on purpose.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HbA1c
A blood test of average blood sugar over the past two to three months, given as a percentage or in mmol/mol. 6.5% (48 mmol/mol) or more is the usual threshold for diabetes, normally confirmed by a second test.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
INR, PT and aPTT (clotting tests)
Blood tests of how long blood takes to clot. The INR is the prothrombin time (PT) put on a common scale; about 1 is usual for someone not taking a blood thinner.
Criteria often make an exception for people on a blood thinner such as warfarin, whose INR is raised on purpose.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
4 Months of supervised winter swimming.
Behavioral: Winter Swimming
No winter swimming activities.
Behavioral: Control group
Supervised Winter Swimming in Copenhagen
No winter swimming activities.
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.
Time frame: Day 0 (before intervention) and Day 120 (after intervention)
Difference between groups in change in glycemic control
Glycemic control is measured using a 4 hour mixed meal tolerance test. Difference between groups in change in the mean MMTT glucose levels during the MMTT (post minus pre intervention) will be calculated.
Time frame: Day 0 (before intervention) and Day 120 (after intervention)
Plan to share: No
No publications or documents are linked to this record.
Ran from Nov 2018 to primary completion in Jun 2021, 30 months.
Of 3,683 non-industry interventional studies with no phase under Obesity, half reached primary completion within 23 months of starting (the median), counting those still running; a quarter within 10 and three quarters within 43. This study's 30 months is above that.
Counting every sponsor, half of 3,846 studies reached it within 22 months; a quarter within 9 and three quarters within 42.
How these figures are worked out, and which studies are left out of them.
This study is active, not recruiting, as verified in May 2025. You cannot join it, but the record below documents what was studied.
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Kristian Karstoft