Relaxation breathing improves human glycemic response - Wilson et al. (2013)
Key Points
Relaxation breathing (constant inhale with progressively longer exhales) significantly lowered blood sugar 30 minutes after an oral glucose tolerance test (OGTT) when compared to controls
Activation of the parasympathetic nervous system likely improved insulin response to OGTT, and might have also improved insulin sensitivity
The Breathing Diabetic Summary
This is one of those amazing papers that, despite having a low sample size, hints that the amazing benefits of slow breathing for diabetics. The authors set out to isolate the specific effects of slow breathing on glycemic response. They were motivated by other studies that have found that yoga has positive impacts on blood sugar, but they wanted to look directly at breathing without any other physical activity.
They had two study groups, a control group and a group that performed relaxation breathing (RB). The RB protocol was to inhale for 2 sec, exhale for 1 sec, inhale for 2 sec, exhale for 2 sec, inhale for 2 sec, exhale for 3 sec, etc., until the exhale reached 10 seconds. So, they are keeping the inhale constant while progressively increasing the exhale. Exhaling for longer than you inhale is a classic way to relax and activate the parasympathetic nervous system, hence the title of the paper “Relaxation Breathing improves human glycemic response.” The patients performed one cycle of this breathing every ten minutes for 30 minutes, and then they were given an oral glucose tolerance test (OGTT). They continued to practice the RB every 10 minutes for 90 minutes after the OGTT was administered. So, over the 2 h period of this protocol, the participants performed the breathing 12 times. The control group did not do any breathing.
(After reading this paper, I started using this breathing technique quite often. For me, I’ve found it’s nice to do while lying in bed to go to sleep. I also find it helpful at the beginning of a breathing/meditation session just to calm everything down. Finally, I also use it while walking, for example, inhaling for 2-3 steps, and progressively increasing the number of steps I exhale over until I experience a moderate air hunger, then restarting.)
The results were pretty remarkable. I encourage you to look at the paper yourself to see the plot of the glycemic response to the OGTT (their FIG. 2). The RB group had a significantly lower blood sugar 30 minutes after the OGTT (~37 mg/dL lower). After an hour, the two groups were approximately the same, but the reduced spike at 30 minutes was very impressive.
They also found that the differences in insulin were not significantly different, which would hint at increased insulin sensitivity. However, when looking at the numbers, the insulin was higher in the RB group than the controls, even if not “significant.” My speculation is that the relaxation breathing activated the parasympathetic nervous system, which improved the insulin response of the participants (note that these were healthy, non-diabetic subjects). See links below on how the parasympathetic nervous system is critical for insulin response:
Obviously, this is extremely important to type-2 diabetics who still produce insulin, but it still relevant to type 1 diabetics as well. If the parasympathetic nervous system activates insulin release, it probably also primes the body to use that insulin (thanks, evolution!). So, even if us type-1 diabetics will not benefit from the better insulin response, we likely will benefit from better insulin sensitivity due to RB, something these authors speculated as well.
Overall, this paper found that relaxation breathing improved the glycemic response of participants to an OGTT.Although the exact mechanisms are not clear, it seems likely that activation of the parasympathetic nervous system improved the insulin response of the RB group, and might have also improved insulin sensitivity.And, we have another easy-to-implement breathing technique that has now been scientifically shown to improve glycemic response.Try a cycle for yourself and see how you feel afterward.
Abstract from Paper
Objectives: This study evaluated a simple relaxation breathing exercise for acute improvement of postprandial glycemic and insulinemic status.
Design: Healthy human subjects were randomized to control breathing (CB; n = 13) or a relaxation breathing exercise (RB; n = 13) that was repeated every 10 minutes for the 30 minutes before and 90 minutes after consuming a glucose challenge (oral glucose tolerance test; OGTT; 75 g/240 mL). Blood samples were collected before, and 30, 60, and 90 minutes post OGTT for glucose and insulin analysis.
Results: Blood glucose at 0 minutes (pre-OGTT), and 30, 60, and 90 minutes post-OGTT with continued RB was 93.7 – 1.9, 136.5 – 8.1, 165.7 – 8.1, and 130.2 – 6.9 mg/dL, and 97.1 – 2.4, 173.1 – 8.4, 158.7 – 11.1, and 137.1 – 10.1 with CB, respectively. RB blood glucose was significantly lower at 30 minutes than CB. Glucose area under the curve (AUC) for CB and RB were not significantly different. Plasma insulin for both CB and RB was significantly increased relative to baseline at 30, 60, and 90 minutes. Insulin values for RB tended to be higher than CB at 30 and 60 minutes, although the difference was not statistically significant. Insulin AUC for CB and RB was not significantly different.
Conclusions: Relaxation breathing acutely improves the glycemic response of healthy subjects, and breathing pattern could be important for interpretation of glycemic index measurements.
Journal Reference:
Ted Wilson, Sarah E. Baker, Michelle R. Freeman, Mark R. Garbrecht, Frances R. Ragsdale, Daniel A. Wilson, and Christopher Malone, (2013) Relaxation Breathing Improves Human Glycemic Response, The Journal of Alternative and Complementary Medicine, 19 (7), 633-636, DOI: 10.1089/acm.2012.0603.