Warm Water Immersion Similarly Reduces Arterial Blood Pressure in Obese Type 2 Diabetic and Healthy Individuals

Abstract

This project tested the hypothesis that an acute bout of hyperthermia will reduce arterial blood pressure during and following the exposure, but the response will be attenuated in obese type 2 diabetics. Eleven obese type 2 diabetics (T2D) (50.1 ± 12 y, 45 ± 7.1% fat mass, 7.5 ± 1.8% HbA1C) and nine similarly aged healthy controls (HC) (41.1 ± 13.7y; P=0.185, 33.4 ± 7.8% fat mass; P=0.009, 5.3 ± 0.4%, HbA1C; P=0.007) with similar resting blood pressure (T2D: 125 ± 27/ 77 ± 14, HC: 122 ± 14/ 81 ± 10, P>0.05) were assessed. Subjects underwent a whole body passive heated stress (1 hour resting in 39.4 ± 0.4°C water) followed by 1 hour post immersion recovery under normal ambient temperatures. Both groups were similarly heat stressed (ΔTre, 1.4 ± 0.4°; ΔTsk, 6.5 ± 0.8; and ΔHR from rest, 33.5 ± 8.3 bpm) at the end of warm water immersion. In comparison to pre‐immersion values, there were no interactive effect for mean arterial blood pressure (MAP, time x group; P=0.145). MAP was reduced (P<0.01) from minute 10 (ΔMAP, T2D: 10.2 ± 5.5, HC: 14.8 ± 8.4) through minute 60 of immersion (T2D: 12.8 ± 8.1, HC: 13.9 ± 11.2) and remained below pre‐immersion values (P=0.004) up to 20 minutes post immersion in both groups (T2D: 10.8 ± 9.6, HC 7.6 ± 6.8 mmHg). These data indicate that head‐out warm water immersion results in similar hypotensive responses in both groups. Thus, passive heat stress may offer a therapeutic benefit to both healthy and diabetic populations.