The Effect of Chronic Passive Heating on Insulin Sensitivity and Cardiovascular function on people with type 2 diabetes Mellitus: a pre and post-test trial

research participant in hot tub

This project is exploring a potential new treatment for type 2 diabetes using passive heating

  • 07 October 2021
  • 4 min read

Passive heating can reduce blood sugar levels in a similar way to exercise in people without diabetes. We want to see if this is the same in people with type 2 diabetes and if so, how. We are looking for individuals with type 2 diabetes and that are 35 years or above (post-menopausal for women). Due to safety we are unable to enrol anyone who: cannot sense temperature in their fingers and toes, have had a heart attack or any other serious heart trauma, are unable to perform exercise, have skin ulcerations or smoked within the last 3 months. The study will take place in the Spinnaker building of the University of Portsmouth. Taking part will involve 15 visits (option to do fewer visits if needed, 11 minimum). Most visits will last just over 1 hour, however, the second and last are between 3 and 4 hours long.

It is possible that taking part in this study will temporarily improve your blood sugar levels and control, improve your heart and blood vessel health (including reduced blood pressure), burn calories (i.e. weight loss), improve fitness, and improved muscle strength and function. Additionally, the findings from this study will not directly have implications for your health but it will inform further work which could result in a new treatment for type 2 diabetes.

Who should be able to apply to participate?

Staff, Students, General public

Participant Characteristics

  • Must be diagnosed with type 2 diabetes
  • Aged 35 and above (post-menopausal for female)

What will participants be doing?

As mentioned before, taking part will involve 15 visits (option to do fewer visits if needed, 11 minimum). Most visits will last just over 1 hour, however, the first and last will be between 3 – 4 hours long. The hot tub visits all need to be completed within a 14 day period. The first visit, should you decide to take part, will involve you giving your consent, then having a health screening and then familiarising with the equipment and procedures that will be being used in the rest of the study. This will involve: a blood sample (5 mL = ~ 1 teaspoon), a 12-lead ECG, blood pressure measurements and equipment demonstration.

The second and last visits will be require you: to come in from an overnight fast, have blood samples taken (no more than 30 mL per sample = ~ 5-6 teaspoons), breath into a mask covering your mouth and nose, consume a sugary drink and have blood vessel tests (e.g. ultrasound scan on your arm and we will also look at how your small blood vessels work by putting small amounts of two blood vessel relaxers on the skin). A snack will be provided in the second and last visit. In the visits between the second and the last, you will be asked to bathe for 1 h in a hot tub. Before you get in the hot tub you will be given a rectal thermistor (a thin flexible tube, necessary for your safety) to self-insert which you will do the same time as you are getting changed (bathing suit and t-shirt). Beforehand, you will be given instructions on how to insert the thermistor.

Where will participants be going?

Spinnaker Building, Cambridge Road, Portsmouth, PO1 2ER

Parking will be provided.

Project end date

31 Jan 2022


Email the principal investigator, Thomas James at

Ethics code

21/LO/0180 from London - Queen Square Research Ethics Committee