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This article was originally published in Diabetes Health in August, 2008.
Is it possible that a dip in the hot tub can cause a dip in the blood sugars? According to a pilot study that appeared in the September 16 issue of The New England Journal of Medicine (NEJM), "hot tub therapy" helped a group of type 2s reduce their blood sugars, lose weight and improve sleep patterns.
Philip L. Hooper, MD, of the McKee Medical Center in Loveland, Colorado, studied five type 2 men and three type 2 women, ages 43 to 68. The patients had been suffering from diabetes from three to 14 years.
"These results suggest that hot tub therapy should be further evaluated as a therapy for patients with type 2 diabetes mellitus," says Hooper. "It may be especially helpful for patients who are unable to exercise."
23 mg/dl Reduction in BGs
The temperature of the hot tub water went as high as 104 degrees Fahrenheit. The type 2 subjects sat in the hot tub by themselves with water up to their shoulders for 30 minutes per day, six days per week, for three weeks. The patients' average blood glucose (BG) levels were reduced from 182 mg/dl to 159 mg/dl after three weeks, while HbA1c was reduced from an average of 11.2% to 10.2%. Weight was decreased by an average of 3.75 pounds.
In an interview with Diabetes Health, Hooper explained how one of the study participants, after 10 days, reduced his daily dose of insulin by 18 percent. Another subject, however, showed no reduction in her HbA1c.
"I asked her how her three weeks had gone," Hooper explains. "She said she had a terrible three weeks. Her coworker had quit, her house had gone up for sale and her daughter had a complication in her pregnancy. She said the only quiet time in her day was when she was in the hot tub. In other words, during the study, she was under emotional stress, which will increase blood sugars. Hers, however, stayed the same."
Hooper adds that two other subjects weighed more than 375 pounds, but found their bodies felt much better after three weeks of hot tub therapy.
"Most subjects found that their blood sugars went back up two to three weeks after stopping the study," says Hooper.
Better Exercise Than Swimming
Hooper feels that this study may explain why HbA1cs are better in warm months and worse in cool months.
"I had assumed that the mechanism might be as simple as increasing blood flow to skeletal muscles, which accounts for 80 percent of the insulin-mediated glucose uptake in the body," he says. "However, as I learn more about such issues as heat conditioning and heat shock proteins, it may be more complicated than an increase in blood flow."
Hooper adds that the study may also explain why swimming, which seems like such a good exercise, does not help as much as one would think in terms of BG control or weight loss.
"Swimming does not 'warm' the body," he says.
What About a Hot Bath?
Hooper feels that taking a hot bath could also have the same positive effects as hot tub therapy, but a test would have to be conducted in the same fashion as this study.
"If getting into a hot bath actually raises the body temperature 1 degree Fahrenheit, if immersion to the neck is not important, and if the temperature of the water is kept at 102 to 104 degrees Fahrenheit, then I would speculate that a hot bath would work," says Hooper. "I do have a concern that patients with neuropathy in their legs could burn themselves if they didn't actually check the temperature with a thermometer prior to entering."
Tina, a type 1, writes over the Internet that taking a hot bath is very enjoyable, but makes her BGs go low very quickly.
"I have found that when taking very hot baths, if my BGs are on the way down, like before a meal, the hot bath makes them go very low very quickly," she says. "If my insulin has already peaked, however, the hot bath will cause my BGs to skyrocket very quickly."
Hooper warns that patients taking insulin are also at risk of going too low later in the day or night. He recommends eating a bigger snack before bed or reducing your insulin dose by 5 to 10 percent, assuming that one is getting in the hot tub in the evening.
Are Hot Tubs Safe For People With Diabetes?
Richard Bernstein, MD, FACE, FACN, of the Diabetes Center in Mamaroneck, New York, says that a person with diabetes who sits in a hot tub is "just asking for trouble."
"People with the condition often have nerve damage in their feet, which means they can't feel their feet, so they are likely to get burned...yet feel no pain at the time," says Bernstein, who adds that exercise, weight loss and medications are better ways to lower insulin resistance.
Hooper explains that he has the same concern for people with neuropathy and suggests that they could very well burn themselves if they do not actually check the temperature before entering the hot tub.
Tammy Villanueva, a type 1, writes over the Internet that she notices a drop in her BGs after sitting in a hot tub for more than 15 minutes or a hot bath for more than 30 minutes. She says her biggest concern is passing out after getting out of the hot tub.
"I never notice the signs of lower blood sugars until after I get out of the hot tub," says Villanueva. "The relaxation can mimic the low."
Hooper admits that blood pressure also drops when exiting a hot tub. For his study, participants were assisted from the hot tub and offered a bench to sit on. Hooper says people with diabetes should always exit the tub slowly and perhaps with assistance.
Joan Hoover, Diabetes Health's patient advocate advisor, is surprised at the suggestion that hot tubs might be beneficial for people who have type 2 diabetes.
"Every public hot tub I've ever seen, in hotels and Y clubs, has a warning sign to caution pregnant women, people with diabetes and other people who have high blood pressure," says Hoover.
Hooper says that patients who hot tubbed in the morning found they were rather 'washed out' afterwards. He adds that they quickly learned to hot tub in the late afternoon or evening.
"They then slept better and felt better," he says.
Sarah Elliott of Three Rivers, California, is the mother of an 8-year-old, type 1 boy. When her son was diagnosed in April 1998, she heard all the horror stories about diabetes, but only one stuck in her mind.
"It was about a 14-year-old boy with type 1 diabetes who died in his hot tub," she recalls. "Apparently, this boy had come home from a football game, went into the hot tub and was found dead. I told my concerns to our diabetes educator and she informed me that the boy had most likely drowned after going too low and passing out."
When Elliot heard about this, she concluded that her son could never sit in a hot tub unsupervised, no matter what his age.
"That way, if an incidence of low blood sugar does occur, he can be assisted out of the water, in case he can't do it himself," she says.
Hooper admits that patients taking insulin "are at risk of going low with their blood sugar later in the day or night if they have hot tubbed."
Helen Germann of Plano, Texas, points out that approximately 40 percent of people with diabetes die from heart problems. In addition to having diabetes, Germann has tachycardia, or rapid beating of the heart, and feels that hot tubs can aggravate that condition.
"I wouldn't try this kind of 'exercise' without a doctor's okay," says Germann, adding that people with diabetes also tend to have dry skin, and sitting in a hot tub for this length of time could create skin problems. She also points out that chlorine could affect dry skin. "I've been told to take only short, warm showers and use lots of lotion."
Is it Fun?
Diane Pearson, RN, CDE, founder of Diabetes Care Consultants in San Diego, thinks that socialization might be another component that contributes to a person's BG control.
"This study didn't mention what went on the hot tub," she says. "Did subjects chat with one another? Did they discuss their problems? Offer encouragement?"
Hooper explains that patients in the study did not overlap their visits with one another, so there was no socialization, other than with employees at the testing facility who welcomed them and helped them out of the hot tub afterwards.
"Patients seemed to enjoy the pause in their day when they 'had to' go sit in the hot tub," says Hooper. "It provided a break in their routines and gave them time to themselves. I do not underestimate that there were some real psychological benefits to getting into the tub."
Joseph Prendergast, MD, president of Diabetes Advocates in Atherton, California, says that Hooper's NEJM study may be the best science we will ever see on this situation.
"But, it may well be useful, if only to give patients something fun to do rather than an inappropriate lifestyle," he says. "It is a good thing for most patients hoping for more spiritual improvement rather than medical."
Joan Hoover also feels that if hot tub therapy does no harm, it is probably the nicest therapy ever recommended to people with diabetes.
"People with diabetes are usually asked to do miserable deeds like inject, bleed, diet and exercise," she says.
Nurse Recommends Other Therapies
Margaret Wilkman, RN, MPH, CDE, thinks hot tub therapy is an interesting notion, but would not recommend it.
"I wonder if these patients would have achieved the same benefit if they practiced mindful meditation or biofeedback for 30 minutes, three times a week," says Wilkman, who recommends other exercises for type 2s who do not have the capacity for higher impact forms of exercise. "Water aerobics and armchair exercises may offer beneficial forms of exercise for patients who do not tolerate the impact of walking or jogging."
Prendergast adds that many patients have told him that they get improved glucose control with deep massage.
"They have said that they feel it is due to increased circulation to the muscles," he says. "Could this be what the hot tub did for those in the study?"
Hooper is in the process of writing a grant for further research in this area from the National Institutes of Health, the American Diabetes Association and possibly the American Heart Association. He says many questions have been raised by this study, including what the long-term effects will be on blood sugar control, weight, blood pressure, lipids, well-being, exercise conditioning and heat tolerance?
"My study was a pilot study, which was published in order to provide a new thought in the management of diabetes," says Hooper. "It cannot be endorsed as an 'approved' method of therapy at this time."