Trial Outcomes & Findings for Chronic Passive Heating in Individuals With T2DM (NCT NCT04858321)

NCT ID: NCT04858321

Last Updated: 2025-01-03

Results Overview

Does chronic passive heating improve insulin sensitivity? Calculated using the QUICKI for fasting and Gutt for post-prandial, with glucose and insulin concentrations. A higher value means they have better insulin sensitivity.

• Recruitment status: COMPLETED
• Study phase: NA
• Target enrollment: 17 participants
• Primary outcome timeframe: Change from pre (day 1) - post 8-12 days of 1 hour of passive heating
• Results posted on: 2025-01-03

Participant Flow

Pre-post design, not an RCT. Therefore no assignment details.

Participant milestones

Measure	Passive Heating 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days. Passive heating: 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days.
Overall Study STARTED	17
Overall Study COMPLETED	14
Overall Study NOT COMPLETED	3

Reasons for withdrawal

Measure	Passive Heating 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days. Passive heating: 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days.
Overall Study Withdrawal by Subject	3

Baseline Characteristics

Race and Ethnicity were not collected from any participant.

Baseline characteristics by cohort

Measure	Passive Heating n=14 Participants 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days. Passive heating: 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days.
Age, Continuous	65 years STANDARD_DEVIATION 8 • n=14 Participants
Sex: Female, Male Female	6 Participants n=14 Participants
Sex: Female, Male Male	8 Participants n=14 Participants
Region of Enrollment United Kingdom	14 Participants n=14 Participants
Height	1.68 meters STANDARD_DEVIATION 0.1 • n=14 Participants
Mass	85 kg STANDARD_DEVIATION 19 • n=14 Participants
BMI	30 kg/m2 STANDARD_DEVIATION 5.2 • n=14 Participants
HbA1c	66 mmol/mol STANDARD_DEVIATION 27 • n=14 Participants
T2DM duration	10 years STANDARD_DEVIATION 8 • n=14 Participants
History of microvascular disease	21 % of cohort n=14 Participants
SBP	136 mmHg STANDARD_DEVIATION 19 • n=14 Participants
DBP	81 mmHg STANDARD_DEVIATION 11 • n=14 Participants

PRIMARY outcome

Timeframe: Change from pre (day 1) - post 8-12 days of 1 hour of passive heating

Does chronic passive heating improve insulin sensitivity? Calculated using the QUICKI for fasting and Gutt for post-prandial, with glucose and insulin concentrations. A higher value means they have better insulin sensitivity.

Outcome measures

Measure	Passive Heating n=14 Participants 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days. Passive heating: 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days.
Insulin Sensitivity Fasting - pre	0.31 AU Standard Deviation 0.03
Insulin Sensitivity Fasting - post	0.33 AU Standard Deviation 0.04
Insulin Sensitivity Post-prandial - pre	0.10 AU Standard Deviation 0.04
Insulin Sensitivity Post-prandial - post	0.10 AU Standard Deviation 0.05

SECONDARY outcome

Timeframe: pre - post following 8-12 days of 1 hour of passive heating

Does chronic passive heating reduce plasma [glucose]?

Outcome measures

Measure	Passive Heating n=14 Participants 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days. Passive heating: 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days.
Plasma Glucose Concentration Fasting - pre	10.06 mmol/L Standard Deviation 4.51
Plasma Glucose Concentration Fasting - post	9.95 mmol/L Standard Deviation 4.58
Plasma Glucose Concentration Post-prandial - pre	17.34 mmol/L Standard Deviation 7.34
Plasma Glucose Concentration Post-prandial - post	16.84 mmol/L Standard Deviation 6.49

SECONDARY outcome

Timeframe: pre - post following 8-12 days of 1 hour of passive heating

Does chronic passive heating increase plasma [eHSP70]?

Outcome measures

Measure	Passive Heating n=14 Participants 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days. Passive heating: 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days.
Plasma eHSP70 Concentration Pre	2435 pg/mL Standard Deviation 984
Plasma eHSP70 Concentration Post	2524 pg/mL Standard Deviation 790

SECONDARY outcome

Timeframe: pre - post following 8-12 days of 1 hour of passive heating

Does chronic passive heating reduce plasma [IL-6]?

Outcome measures

Measure	Passive Heating n=14 Participants 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days. Passive heating: 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days.
Plasma IL-6 Concentration Pre	5.60 pg/mL Standard Deviation 10.46
Plasma IL-6 Concentration Post	5.46 pg/mL Standard Deviation 8.47

SECONDARY outcome

Timeframe: pre - post following 8-12 days of 1 hour of passive heating

Does chronic passive heating increase plasma [IL-10]?

Outcome measures

Measure	Passive Heating n=14 Participants 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days. Passive heating: 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days.
Plasma IL-10 Concentration Pre	13.55 pg/mL Standard Deviation 35.88
Plasma IL-10 Concentration Post	12.50 pg/mL Standard Deviation 31.47

SECONDARY outcome

Timeframe: pre - post following 8-12 days of 1 hour of passive heating

Does chronic passive heating reduce plasma resting metabolic rate?

Outcome measures

Measure	Passive Heating n=14 Participants 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days. Passive heating: 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days.
Resting Metabolic Rate Pre	1987 kcal/day Standard Deviation 512
Resting Metabolic Rate Post	1855 kcal/day Standard Deviation 380

SECONDARY outcome

Timeframe: pre - post following 8-12 days of 1 hour of passive heating

Does chronic passive heating improve macrovascular function? Measured via ultrasound

Outcome measures

Measure	Passive Heating n=14 Participants 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days. Passive heating: 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days.
Flow Mediated Dilation Pre	2.88 % increase from baseline diameter Standard Deviation 1.81
Flow Mediated Dilation Post	2.45 % increase from baseline diameter Standard Deviation 1.56

SECONDARY outcome

Timeframe: pre - post following 8-12 days of 1 hour of passive heating

Does chronic passive heating improve microvascular function? Assessed via iontophoresis or the forearm with ACh and Insulin, Area under the curve is the unit. (CVC = skin flux/MAP; flux/mmHg-1)

Outcome measures

Measure	Passive Heating n=14 Participants 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days. Passive heating: 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days.
Cutaneous Vascular Conductance Insulin AUC - pre	1.11 flux/mmHg Standard Deviation 2.10
Cutaneous Vascular Conductance Insulin AUC - post	0.81 flux/mmHg Standard Deviation 0.99
Cutaneous Vascular Conductance ACh AUC - pre	1.52 flux/mmHg Standard Deviation 1.60
Cutaneous Vascular Conductance ACh AUC - post	2.06 flux/mmHg Standard Deviation 2.77

SECONDARY outcome

Timeframe: pre - post following 8-12 days of 1 hour of passive heating

Does chronic passive heating reduce resting heart rate?

Outcome measures

Measure	Passive Heating n=14 Participants 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days. Passive heating: 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days.
Resting Heart Rate Pre	67 beats/min Standard Deviation 12
Resting Heart Rate Post	64 beats/min Standard Deviation 11

SECONDARY outcome

Timeframe: pre - post following 8-12 days of 1 hour of passive heating

Does chronic passive heating increase stroke volume? Measured noninvasively via thoracic impedance

Outcome measures

Measure	Passive Heating n=14 Participants 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days. Passive heating: 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days.
Stroke Volume Index Pre	54.6 mL/m2 Standard Deviation 13.3
Stroke Volume Index Post	49.4 mL/m2 Standard Deviation 11.3

SECONDARY outcome

Timeframe: pre - post following 8-12 days of 1 hour of passive heating

Does chronic passive heating increase cardiac output? Measured noninvasively via thoracic impedance. L/min/m2 is the unit.

Outcome measures

Measure	Passive Heating n=14 Participants 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days. Passive heating: 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days.
Cardiac Output Index Pre	3.57 L/min/m2 Standard Deviation 0.74
Cardiac Output Index Post	3.05 L/min/m2 Standard Deviation 0.54

SECONDARY outcome

Timeframe: Pre- v post 8-12 1 h hot water immersions

TNF-alpha

Outcome measures

Measure	Passive Heating n=14 Participants 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days. Passive heating: 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days.
TNF-alpha Pre	10.51 pg/mL Standard Deviation 18.65
TNF-alpha Post	10.15 pg/mL Standard Deviation 18.14

SECONDARY outcome

Timeframe: Pre- v post 8-12 1 h hot water immersions

Butyric acid

Outcome measures

Measure	Passive Heating n=14 Participants 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days. Passive heating: 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days.
Butyric Acid Pre	285 pg/mL Standard Deviation 294
Butyric Acid Post	405 pg/mL Standard Deviation 458

SECONDARY outcome

Timeframe: Pre- v post 8-12 1 h hot water immersions

Systolic blood pressure

Outcome measures

Measure	Passive Heating n=14 Participants 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days. Passive heating: 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days.
SBP Post	127 mmHg Standard Deviation 15
SBP Pre	136 mmHg Standard Deviation 19

SECONDARY outcome

Timeframe: Pre- v post 8-12 1 h hot water immersions

Diastolic blood pressure

Outcome measures

Measure	Passive Heating n=14 Participants 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days. Passive heating: 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days.
DBP Pre	81 mmHg Standard Deviation 11
DBP Post	80 mmHg Standard Deviation 10

SECONDARY outcome

Timeframe: Pre- v post 8-12 1 h hot water immersions

Mean arterial pressure

Outcome measures

Measure	Passive Heating n=14 Participants 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days. Passive heating: 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days.
MAP Pre	99 mmHg Standard Deviation 11
MAP Post	95 mmHg Standard Deviation 11

SECONDARY outcome

Timeframe: Pre- v post 8-12 1 h hot water immersions

Nitrates + nitrites

Outcome measures

Measure	Passive Heating n=14 Participants 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days. Passive heating: 8-12 x1 h water immersion (to the clavicle, @40 °C, rectal temperature \~38.5 °C and \<39 °C) sessions over a period of 14 days.
NOX Pre	74.5 micromolar Standard Deviation 23.7
NOX Post	67.3 micromolar Standard Deviation 22

Adverse Events

Passive Heating

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

Serious adverse events

Adverse event data not reported

Other adverse events

Adverse event data not reported

Additional Information

Dr Anthony Shepherd

University of Portsmouth

Phone: 02392845289

Email: ant.shepherd@port.ac.uk

Results disclosure agreements

• Principal investigator is a sponsor employee
• Publication restrictions are in place