Heart rate and blood pressure variability, and baroreflex sensitivity, during heat exposure in persons with type 2 diabetes and hypertension
8 affiliations
- 1Department of Community Medicine, Faculty of Health Sciences, UiT the Arctic University of Norway, Tromsø, Norway
- 2Department of Occupational and Environmental Medicine, University Hospital of North Norway, Tromsø, Norway
- 3Research Unit of Biomedicine and Internal Medicine, University of Oulu, Oulu, Finland
- 4Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Oulu, Finland
- 5Clinical Neurophysiology, Department of Diagnostics, Oulu University Hospital, Oulu, Finland
- 6Clinical Neurophysiology, Research Unit of Health Sciences and Technology, Faculty of Medicine, Medical Research Center, University of Oulu, Oulu, Finland
- 7Research Unit of Population Health, University of Oulu, Oulu, Finland
- 8Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
Abstract
The autonomic nervous system regulates cardiovascular homeostasis during stressors such as heat, but the effects of type 2 diabetes (T2D) with hypertension on such responses are unclear. Twenty male participants (10 with type 2 diabetes and hypertension and 10 age-matched healthy controls; mean ages 64 ± 4.14 and 63 ± 5.42 years) underwent a 90-minute whole-body heat exposure at 40 °C and 50% relative humidity. Heart rate variability (HRV), baroreflex sensitivity (BRS), and blood pressure variability (BPV) were assessed before, during and after the heat exposure. Heat exposure increased heart rate in both groups but this response was less in T2D (5.43 bpm; ~ 7% increase) versus controls (13.96 bpm; ~ 22% increase; p = 0.014). Similarly, reductions in HRV indices to heat stress were generally smaller in magnitude among participants with T2D. For example, high-frequency power (HF RR) decreased by 31.21 ms² (~54.5% reduction) in T2D because of heat exposure, compared with a reduction of 179.35 ms² (~74% reduction) in controls (p = 0.038). Further, LF BRS decreased by 1.07 ms/mmHg (~25% reduction) vs. 3.96 ms/mmHg (~51% reduction) (p = 0.021), HF BRS by 1.58 ms/mmHg (~35% reduction) vs. 4.15 ms/mmHg (~62% reduction) (p = 0.034), and mean BRS by 1.18 ms/mmHg (~26% reduction) vs. 4.16 ms/mmHg (~58% reduction) (p = 0.010) in those with T2D versus controls, respectively. Low-frequency power (LF RR), LF/HF ratio and BPV parameters also showed smaller (though nonsignificant) changes in T2D. Overall, combined T2D and hypertension produced blunted autonomic responses to short-term heat exposure, potentially increasing vulnerability to temperature extremes.
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BibTeX
@article{rafieian2026heart,
title = {{Heart rate and blood pressure variability, and baroreflex sensitivity, during heat exposure in persons with type 2 diabetes and hypertension}},
author = {Mojdeh Rafieian and Erlend Hoftun Farbu and Anje Christina Höper and Rasmus Valtonen and Mika Kallio and Henna Hyrkäs-Palmu and Craig Crandall and Tiina Maria Ikäheimo},
journal = {PLOS One},
year = {2026},
month = oct,
doi = {10.1371/journal.pone.0361367},
url = {https://doi.org/10.1371/journal.pone.0361367},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Heart rate and blood pressure variability, and baroreflex sensitivity, during heat exposure in persons with type 2 diabetes and hypertension
AU - Mojdeh Rafieian
AU - Erlend Hoftun Farbu
AU - Anje Christina Höper
AU - Rasmus Valtonen
AU - Mika Kallio
AU - Henna Hyrkäs-Palmu
AU - Craig Crandall
AU - Tiina Maria Ikäheimo
PY - 2026
DA - 2026/10/27
JO - PLOS One
DO - 10.1371/journal.pone.0361367
UR - https://doi.org/10.1371/journal.pone.0361367
AB - The autonomic nervous system regulates cardiovascular homeostasis during stressors such as heat, but the effects of type 2 diabetes (T2D) with hypertension on such responses are unclear. Twenty male participants (10 with type 2 diabetes and hypertension and 10 age-matched healthy controls; mean ages 64 ± 4.14 and 63 ± 5.42 years) underwent a 90-minute whole-body heat exposure at 40 °C and 50% relative humidity. Heart rate variability (HRV), baroreflex sensitivity (BRS), and blood pressure variability (BPV) were assessed before, during and after the heat exposure. Heat exposure increased heart rate in both groups but this response was less in T2D (5.43 bpm; ~ 7% increase) versus controls (13.96 bpm; ~ 22% increase; p = 0.014). Similarly, reductions in HRV indices to heat stress were generally smaller in magnitude among participants with T2D. For example, high-frequency power (HF RR) decreased by 31.21 ms² (~54.5% reduction) in T2D because of heat exposure, compared with a reduction of 179.35 ms² (~74% reduction) in controls (p = 0.038). Further, LF BRS decreased by 1.07 ms/mmHg (~25% reduction) vs. 3.96 ms/mmHg (~51% reduction) (p = 0.021), HF BRS by 1.58 ms/mmHg (~35% reduction) vs. 4.15 ms/mmHg (~62% reduction) (p = 0.034), and mean BRS by 1.18 ms/mmHg (~26% reduction) vs. 4.16 ms/mmHg (~58% reduction) (p = 0.010) in those with T2D versus controls, respectively. Low-frequency power (LF RR), LF/HF ratio and BPV parameters also showed smaller (though nonsignificant) changes in T2D. Overall, combined T2D and hypertension produced blunted autonomic responses to short-term heat exposure, potentially increasing vulnerability to temperature extremes.
SN - 1932-6203
ER -