The claim

“Cold exposure improves insulin sensitivity by 43%.”

Stretched. The 43% came from eight men with type 2 diabetes who spent about six hours a day in 14–15°C air for ten days. When the same group repeated it at 16–17°C and kept people from shivering, insulin sensitivity didn't improve.

Updated Sep 24, 2026 · 2 studies reviewed

The claim pulls a real finding well past what the study showed.

People say it in places like these

Podcasts
Cold exposure improves insulin sensitivity by 43 percent, so plunging helps control blood sugar.
Wellness sites
Ten days of cold raised insulin sensitivity by almost half in people with diabetes.

The research found this

Dutch researchers reported the 43% in Nature Medicine in 2015. Eight patients with type 2 diabetes spent ten days in mild cold. They sat in shorts and a T-shirt in a room whose air and walls were held at 14–15°C.Source 1 · Clinical trialShort-term cold acclimation improves insulin sensitivity in patients with type 2 diabetes mellitusHanssen MJW, Hoeks J, Brans B, et al.. Nature Medicine, 2015.Read the paper ↗PubMed ↗ The group's conference abstract gives the dose as about six hours a day and describes the patients as overweight or obese men around 59 years old. Their peripheral insulin sensitivity (how readily the body's tissues take up sugar in response to insulin) rose about 43%.

The authors traced most of the effect to muscle. There, far more of a sugar-carrying protein called GLUT4 moved to the cell surface, and brown fat took up only slightly more glucose.Source 1 · Clinical trialShort-term cold acclimation improves insulin sensitivity in patients with type 2 diabetes mellitusHanssen MJW, Hoeks J, Brans B, et al.. Nature Medicine, 2015.Read the paper ↗PubMed ↗ Insulin signaling itself didn't change.

Six years later the same group ran a milder version with nine patients and avoided overt shivering. The room averaged 16.4°C, which was about 1.4°C warmer than before, and insulin sensitivity didn't improve.Source 2 · Clinical trialMetabolic responses to mild cold acclimation in type 2 diabetes patientsRemie CME, Moonen MPB, Roumans KHM, et al.. Nature Communications, 2021.Read the paper ↗PubMed ↗ Liver fat and the after-meal levels of glucose and blood fats stayed the same. Because the patients reported far less shivering than in the first study, the authors proposed that some muscle contraction is needed.

In a 2024 study that lasted ten days, researchers cooled 15 adults with overweight or obesity enough to make them shiver for an hour a day. Their oral glucose tolerance (how well the body clears a sugary drink from the blood) improved.Source 3 · Clinical trialCold acclimation with shivering improves metabolic health in adults with overweight or obesitySellers AJ, van Beek SMM, Hashim D, et al.. Nature Metabolism, 2024.Read the paper ↗PubMed ↗ Fasting glucose, triglycerides, free fatty acids and blood pressure got better too. The abstract doesn't give the size of these changes, and the study had no control group.

The dial reads 62°H for four reasons

How the reading adds up

12 + 16 + 14 + 20 = 62°H

EvidenceWhat kind of human evidence exists?
12/25
The researchers tested eight patients with a glucose clamp (a lab measure of insulin sensitivity) before and after ten days of cold, and there was no control group.Source 1 · Clinical trialShort-term cold acclimation improves insulin sensitivity in patients with type 2 diabetes mellitusHanssen MJW, Hoeks J, Brans B, et al.. Nature Medicine, 2015.Read the paper ↗PubMed ↗ None of the insulin studies went past ten days.Source 2 · Clinical trialMetabolic responses to mild cold acclimation in type 2 diabetes patientsRemie CME, Moonen MPB, Roumans KHM, et al.. Nature Communications, 2021.Read the paper ↗PubMed ↗Source 3 · Clinical trialCold acclimation with shivering improves metabolic health in adults with overweight or obesitySellers AJ, van Beek SMM, Hashim D, et al.. Nature Metabolism, 2024.Read the paper ↗PubMed ↗
ConsistencyHave other studies found the same thing?
16/25
When the same Dutch group tried again at 16–17°C and avoided shivering, insulin sensitivity didn't improve in nine patients.Source 2 · Clinical trialMetabolic responses to mild cold acclimation in type 2 diabetes patientsRemie CME, Moonen MPB, Roumans KHM, et al.. Nature Communications, 2021.Read the paper ↗PubMed ↗ A 2024 study that made people shiver for an hour a day found better glucose tolerance, and the authors of the failed repeat proposed that some muscle contraction is needed.Source 3 · Clinical trialCold acclimation with shivering improves metabolic health in adults with overweight or obesitySellers AJ, van Beek SMM, Hashim D, et al.. Nature Metabolism, 2024.Read the paper ↗PubMed ↗Source 2 · Clinical trialMetabolic responses to mild cold acclimation in type 2 diabetes patientsRemie CME, Moonen MPB, Roumans KHM, et al.. Nature Communications, 2021.Read the paper ↗PubMed ↗
MagnitudeDoes the claim match the size of the effect?
14/25
The 43% is the measured change in peripheral insulin sensitivity in eight men with type 2 diabetes.Source 1 · Clinical trialShort-term cold acclimation improves insulin sensitivity in patients with type 2 diabetes mellitusHanssen MJW, Hoeks J, Brans B, et al.. Nature Medicine, 2015.Read the paper ↗PubMed ↗ The claim stretches it to cover cold exposure in general and never mentions the failed repeat.Source 2 · Clinical trialMetabolic responses to mild cold acclimation in type 2 diabetes patientsRemie CME, Moonen MPB, Roumans KHM, et al.. Nature Communications, 2021.Read the paper ↗PubMed ↗
DoseDoes the studied dose match how people use it?
20/25
The men sat in 14–15°C air in shorts and a T-shirt for about six hours a day, and over ten days that adds up to roughly 54–60 hours of cold.Source 1 · Clinical trialShort-term cold acclimation improves insulin sensitivity in patients with type 2 diabetes mellitusHanssen MJW, Hoeks J, Brans B, et al.. Nature Medicine, 2015.Read the paper ↗PubMed ↗ Both studies that measured insulin sensitivity used cold room air.Source 1 · Clinical trialShort-term cold acclimation improves insulin sensitivity in patients with type 2 diabetes mellitusHanssen MJW, Hoeks J, Brans B, et al.. Nature Medicine, 2015.Read the paper ↗PubMed ↗Source 2 · Clinical trialMetabolic responses to mild cold acclimation in type 2 diabetes patientsRemie CME, Moonen MPB, Roumans KHM, et al.. Nature Communications, 2021.Read the paper ↗PubMed ↗

The claim drifts from the data here

The claim treats the 43% as something any cold exposure will do. It took about six hours a day of 14–15°C air for ten days, and a slightly warmer version without shivering produced no gain.Source 1 · Clinical trialShort-term cold acclimation improves insulin sensitivity in patients with type 2 diabetes mellitusHanssen MJW, Hoeks J, Brans B, et al.. Nature Medicine, 2015.Read the paper ↗PubMed ↗Source 2 · Clinical trialMetabolic responses to mild cold acclimation in type 2 diabetes patientsRemie CME, Moonen MPB, Roumans KHM, et al.. Nature Communications, 2021.Read the paper ↗PubMed ↗

It also leaves out that all eight men had type 2 diabetes and that none of these studies tried a short plunge.Source 1 · Clinical trialShort-term cold acclimation improves insulin sensitivity in patients with type 2 diabetes mellitusHanssen MJW, Hoeks J, Brans B, et al.. Nature Medicine, 2015.Read the paper ↗PubMed ↗ The sauna side of the question has its own page.

Put it to use

If blood sugar is your reason to try cold, don't count on a plunge to help. The benefit showed up after hours of cold air a day in a lab, and the studies point to shivering as part of it.Source 1 · Clinical trialShort-term cold acclimation improves insulin sensitivity in patients with type 2 diabetes mellitusHanssen MJW, Hoeks J, Brans B, et al.. Nature Medicine, 2015.Read the paper ↗PubMed ↗Source 3 · Clinical trialCold acclimation with shivering improves metabolic health in adults with overweight or obesitySellers AJ, van Beek SMM, Hashim D, et al.. Nature Metabolism, 2024.Read the paper ↗PubMed ↗

From our sister magazine

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Sauna Monthly · Guide

These cold plunge tubs are worth buying

Sauna Monthly picks its favorites and names the spec that decides between them.

Read it on Sauna Monthly

Check these claims next

72°H

Stretched

Cold

“Cold plunges burn fat by switching on brown fat.”

Cold does switch on brown fat in adults. In the one controlled trial that measured fat, men who spent two hours a day in 17°C air lost 0.7 kg of it over six weeks. Plunges haven't been tested for fat loss.

80°H

Hot air

Heat

“Sauna improves your blood sugar control.”

The only sauna trial with a glucose test found blood sugar rose more after a session. Small hot-tub trials lowered fasting glucose, and a review of randomized heating trials found no effect on fasting glucose or on HbA1c (a longer-term blood sugar measure).

89°H

Hot air

Cold

“Eleven minutes of cold a week is the ideal dose.”

A 2021 paper added up the cold-water habits that seven Danish winter swimmers reported and got 11 minutes a week. The study never assigned or compared a dose, and in the lab it cooled people with blankets that had cold water running through them.

We cited these sources

01Hanssen MJW, Hoeks J, Brans B, van der Lans AAJJ, Schaart G, van den Driessche JJ, et al.. Short-term cold acclimation improves insulin sensitivity in patients with type 2 diabetes mellitus. Nature Medicine. 2015;21(8):863-865. doi:10.1038/nm.3891 PMID 26147760
02Remie CME, Moonen MPB, Roumans KHM, Nascimento EBM, Gemmink A, Havekes B, et al.. Metabolic responses to mild cold acclimation in type 2 diabetes patients. Nature Communications. 2021;12(1):1516. doi:10.1038/s41467-021-21813-0 PMID 33750795
03Sellers AJ, van Beek SMM, Hashim D, Baak R, Pallubinsky H, Moonen-Kornips E, et al.. Cold acclimation with shivering improves metabolic health in adults with overweight or obesity. Nature Metabolism. 2024;6(12):2246-2253. doi:10.1038/s42255-024-01172-y PMID 39643644

People say it in places like these

The research found this

The dial reads 62°H for four reasons

EvidenceWhat kind of human evidence exists?

ConsistencyHave other studies found the same thing?

MagnitudeDoes the claim match the size of the effect?

DoseDoes the studied dose match how people use it?