To answer this question, we’ll look at what is supposed to happen when the body is affected by hot water via shower or bath, and heat. We’ll look at what could be possible reasons for blood sugar levels to show up high, and the effect of what’s in the environment on the blood sugar.
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How the Body Reacts to Water and Heat
The normal reaction of the body after exposure to a warm or hot bath or shower is to lower blood sugar levels. This same effect may be seen when someone has a sauna treatment.
During a hot bath, body temperature will rise as does growth hormone, adrenaline, glucagon, and cortisol. There was a slightly elevated insulin level as well in the healthy patients of this study at the Royal Victoria Infirmary in the United Kingdom. They noted that blood sugar levels stayed constant.
Another study found that the heat of a Finnish sauna affected the absorption of insulin from an injection in 8 patients with Type 1 diabetes. The sauna session was 85 degrees C for 25 minutes (done twice) and it failed to stimulate insulin absorption significantly or to lower blood glucose levels. The body didn’t absorb the insulin and the patients’ blood sugar levels stayed the same.
Bathing in Dead Sea mineral water can cause physiological changes in the endocrine system. At the Ben-Gurion University of the Negev in Beer Sheba, doctors found that those who immersed themselves in a Dead Sea water bath reduced their blood sugar levels of diabetic patients from 163 mg/dl to 151 mg/dl and then to 141 mg/dl an hour later. Those who immersed in non-Dead Sea water baths did not have as much of a change in blood sugar levels.
Hot tub therapy has been also found to benefit diabetes. In one study, diabetic animals that had hot tub treatment significantly improved their blood fats, antioxidant levels, insulin secretion but only a borderline effect on fasting blood glucose.
In healthy volunteers jumping into the cold Baltic Sea, researchers found a mild initial elevation of serum glucose after the shock of the cold water was felt. They attributed this to the stress effects since cortisol was also increased. If you got into the shower and it was cold, the same effect may have happened to you. If you ended your shower with cold water, this could be responsible for the blood sugar increase.
All these types of situations can be considered for your blood sugar levels rising after a shower.
Possible Reasons for Blood Sugar Levels to Rise
Different factors affect the glucose monitor or sensor that you may be using. For example, in one study, the continuous glucose monitoring device results were affected by the room temperature and humidity, the type and duration of physical activity, the adhesion of the sensor and the transmitter and the skin irritation from the device. You might try seeing how these factors are influencing your readings.
In another study of various factory-calibrated continuous glucose monitors, the monitors may be calibrated well or may not be. Whether they are or aren’t, glucose monitors are notorious for their lag time behind changes in blood glucose and their accuracy, stated doctors at the Imperial College in London in April 2020. Newer meters are more likely to be accurate.
In another study of 1035 subjects and their meters, six of the 18 meters were accurate in their readings. Levels of blood sugar fluctuated up to 20% higher than the reference value (what they were supposed to be).
Researchers in Iran found that electromagnetic interference from mobile phones has an adverse effect on the accuracy of home blood glucose monitors. Mobile phones should be at least 50 cm away from home blood glucose monitors before taking any reading.
One more thing that could have caused an increase is what you ate within the last two hours. Any type of food might increase the blood sugar levels within that time frame, whether you take a shower or not.
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