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Ten days of cold air raised insulin sensitivity 43% in eight men with type 2 diabetes

The 2015 Nature Medicine study behind the 43% insulin claim kept eight patients with type 2 diabetes in 14–15°C air for about six hours a day.

The paper

Short-term cold acclimation improves insulin sensitivity in patients with type 2 diabetes mellitus

Hanssen MJW, Hoeks J, Brans B, van der Lans AAJJ, et al.. Nature Medicine, 2015;21(8):863-865.

Read the paper ↗PubMed 26147760 ↗

See the study at a glance

Design
Single-group before-and-after study
People
8 patients with type 2 diabetes
Who they were
Patients with type 2 diabetes. The group's conference abstract describes them as overweight or obese men with an average age of 59.3 and an average BMI of 29.8.
What they did
Ten days of mild cold in a room whose air and walls were held at 14–15°C. Patients sat in shorts and a T-shirt for about six hours a day. The six-hour figure comes from the group's conference abstract.
How long
10 days

These numbers came out of it

43%

Peripheral insulin sensitivity (how muscle and other tissues outside the liver respond to insulin) rose 43% over the ten days on a glucose clamp test.

8

The study had eight patients and no control group.

54–60 h

Over the ten days the patients spent roughly 54 to 60 hours in cold air. The exact total depends on whether the first days were shorter.

The researchers did this

A Dutch group put eight patients with type 2 diabetes through ten days of mild cold. Each day the patients sat for about six hours 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 six-hour figure comes from the group's 2015 conference abstract.

The researchers measured insulin sensitivity with a glucose clamp, and the peripheral measure rose about 43%.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 ↗ Glucose transporters called GLUT4 moved to the surface of muscle cells in much greater numbers. Brown fat took up only slightly more glucose. Insulin signaling and the energy-sensing enzyme AMPK didn't change, so the authors gave muscle most of the credit.

Six years later the same group repeated the experiment at 16–17°C in nine patients and kept them from shivering. This time 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 ↗ The authors of the repeat proposed that the benefit needs some muscle contraction.

The study can't tell you these things

  • Eight patients took part, and there was no control group.
  • The cold came from room air for about six hours a day, and no water was involved.
  • A slightly warmer repeat without shivering found no benefit.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 ↗
  • Ten days is too short to show whether the change lasts or alters the course of diabetes.

People quote it like this

The popular line that cold exposure improves insulin sensitivity by 43% comes from this paper. Said that way, it leaves out that all eight people had type 2 diabetes and sat in cold air for about six hours a day. The same group's milder repeat found no benefit.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 ↗

We cited these sources

  1. 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
  2. 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