Background and rationale{6a}
The prevalence of diabetes mellitus is rising worldwide, especially in the Southeast Asian region [1] and in Sri Lanka it has been projected to rise up to 13.9% by 2030 [2].
In both health and disease, psychological stress plays a major role in determining the well-being of an individual. It affects the individual’s behaviour pattern, biophysical parameters and how the individual copes with disease [3]. It has been postulated that physiological processes are affected by stress through the neuro-endocrine response system. Stress stimulates both the hypothalamic-pituitary-adrenocortical axis and the sympathetic-adrenal-medullary system, which in turn affects a wide range of physiological processes [3]. Chronic stress leads to elevated cortisol levels and results in poor glycaemic control [4] It also indirectly affects glycaemic control through changes in behaviour patterns such as diet and exercise [5]. It has been recognized that stress has a negative effect on quality of life and psychosocial wellbeing [3] in patients with diabetes.
Meditation can be defined as the intentional self-regulation of attention from moment to moment [6]. The roots of most meditation practices have evolved from Buddhism. There are two major areas in meditation: concentration meditation and insightful meditation. Concentration meditation is known as “Samatha” in Theravada Buddhism and involves focussing attention to one thing [6]. Insightful or awareness meditation, which is known as “vipassana” in Theravada Buddhism, does not restrict attention to one thing but emphasizes detached self-observation from one moment to another [6]. However, these two areas are not mutually exclusive and can be described as two aspects of the same meditative state [7]. It has also been viewed as “Samatha” meditation practices leading to stability of the mind, whereas “Vipassana” meditation practices leading to clarity of the mind [7]. Furthermore, a state of stability of the mind is needed to achieve clarity of mind. It is important to understand that Buddhist meditation is not merely a method of relaxation but is aimed at achieving a balance between stability and clarity of mind through practice [7]. The meditative state thus reached is said to be present not only during meditation but also after meditation. The modern term of mindfulness or “Sati” in Buddhist literature, is described as a state of mind achieved through focussing the attention on one thing and being in the present moment. This paves the pathway to achieve a higher state of mind through meditation. The aim is to have focused attention as well as to identify when the attention is deviated and regained [7]. One example is “Anapanasathi” meditation which has been described as keeping the focused attention on breathing and being at the present moment (breath awareness).
In clinical psychology, meditation is defined as “A family of self-regulation practices that focus on training attention and awareness in order to bring mental processes under greater voluntary control and thereby foster general mental well-being and development and/or specific capacities such as calm, clarity, and concentration” [8]. Thus, the core components of meditation practices include focused attention, self-regulation and self-awareness [8].
There is evidence to suggest that meditation-based interventions have positive effects on the management of stress and diabetes [3, 4, 9, 10]. The beneficial effect of meditation on the management of diabetes includes; (a) modulation of neuro-humoral mechanisms that are involved in the management of stress, (b) improvement of overall coping ability with a chronic illness and (c) favourable impact on behaviours such as compliance with diet control, exercise regimen and medications. The development of present moment awareness promotes non-judgmental acceptance of the present status and encourages individuals not to indulge in ruminative thoughts on previous or anticipated events [3]. This aspect of meditation helps the individual to come to terms with chronic illnesses such as diabetes. Therefore, mindfulness meditation practices can be viewed as techniques that sharpen the awareness and bring peace and tranquility. These can also be viewed as mindfulness-based intervention or mind-body therapy.
It has been revealed that walking meditation, a form of concentration meditation, produces multiple favourable effects, such as a reduction in cortisol levels, better glycaemic control and reduced arterial stiffness in patients with type 2 diabetes [4]. Rosenzweig et al. [9] analysed the effects of mindfulness-based stress reduction therapy (MBST) on measures of HbA1c, blood pressure, body weight, and psychological symptoms in patients with diabetes. This pilot study found a reduction in HbA1c of 0.5%, reduction in mean arterial pressure of 6 mmHg, and reduction in depression and anxiety scores.
Researchers have identified the regions of the brain involved during various aspects of meditation [11]. For example, the anterior cingulate cortex and striatum in attention control, multiple prefrontal regions, limbic regions and striatum in emotion regulation and insula, medial prefrontal cortex posterior cingulate cortex and precuneus in self-awareness [11]. The metabolic effects of meditation are through neuro-humoral modulation and stress reduction. Even short-term meditation has been shown to increase the activity of the prefrontal cortex, which is involved in stress regulation. Meditation suppresses the activity of the amygdala and anterior cingulate cortex, which are involved in flight or fight reaction [11] thus reducing stress hormone levels.
In a study that assessed neural activity associated with “Anapanasathi” meditation and love and kindness meditation (Metta), it was noted that after 30 min of meditation, significant changes in functional MRI signals were observed in the right middle frontal gyrus, left inferior parietal lobe, bilateral middle temporal gyrus, bilateral superior temporal gyrus, right inferior temporal gyrus, and left middle occipital gyrus both in novices and experienced meditators [12]. These findings are similar to the other studies performed in long-term meditators [11]. Thus, it can be hypothesized that the relaxation response thus brought about through meditation leads to beneficial effects such as improvement of glycaemic control through mechanisms such as reduction of stress hormone levels.
Furthermore, it has been found that mind body therapies such as yoga, tai chi, qigong, and meditation may supplement the conventional care and management of metabolic syndrome [13].
Meditation exerts changes in autonomic functions as well. In an Indian study, it was shown that parasympathetic tone was significantly higher in the meditators than in the control group [14]. As autonomic neuronal dysfunction is related to diabetes control and many complications of diabetes (gastrointestinal dysfunction and cardiac autonomic dysfunction), it will be useful to investigate the changes in autonomic functions, in patients with diabetes when meditation is practised.
Intestinal dysmotility due to diabetic autonomic neuropathy [15] and diabetic enteric neuropathy has been implicated as the main reason for gastrointestinal complications such as small intestinal bacterial overgrowth [16], gastro-paresis, slow-transit constipation and diabetic diarrhoea. These complications lead to poor glycaemic control owing to erratic absorption of glucose [15]. Stress has been shown to increase gastric emptying time, increase distal colonic motility and accelerate small intestinal transit [17]. It is possible to hypothesize that psychological stress-induced changes in intestinal motility have a negative impact on glycaemic control due to erratic glucose absorption even in the absence of diabetes-related autonomic neuropathy and enteric neuropathy.
The effects of cardiac autonomic neuropathy, such as reduced heart rate variability during deep breathing, decreased baroreflex sensitivity, and orthostatic hypotension [18], can be assessed noninvasively, by 5 simple tests (Ewing et al.) [19]; cardiac autonomic reflex testing (CART) [19]. However, the heart rate response to deep breathing is the test that is most frequently utilized because of its high reproducibility and specificity [20].
There is evidence from a small study involving healthy adults that meditation causes an increase in heart rate variability and causes a decrease in the low-frequency to high-frequency ratio (more predominant vagal tone), which indicates improved autonomic function [21]. Furthermore, it has been shown that, in diabetic cardiac autonomic neuropathy, stress decreases high-frequency heart rate variations [22]. Thus, it can be hypothesized that the stress-relieving effect of meditation will have an effect on reduction of low-frequency to high-frequency heart rate variations, indicating better autonomic function. Improvement of cardiac autonomic testing can be taken as a marker of improvement of overall autonomic functions, which might have beneficial effects on the sympathetic-adrenal medullary system, thus improving the glycaemic control.
Thus, it can be hypothesized that the mechanisms underlying the bio-physiological effects of meditation would be through reduction of stress hormones (cortisol), improvement of insulin resistance and improvement of autonomic dysfunction [3].
Therefore, we report the original protocol of the study aiming to identify the impact of meditation on glycaemic control and the possible mechanisms, such as modulation of the autonomic nervous system, reduction of cortisol levels, improvement in gut transit time and improvement in insulin resistance.
To date, there had not been any clinical trial conducted in Sri Lanka studying the effects of meditation in patients with diabetes. The acceptability of meditation is likely to be high in Sri Lanka, with a population of over 70% Buddhists (Department of Senses and Statistics 2012). With the growing population of diabetes in Sri Lanka, exploration of the effects of mind-body therapies such as meditation is timely, as it is cost-effective, non-invasive and has minimal negative effects. If proven effective, in the future, meditation can be successfully incorporated into the comprehensive management of patients with diabetes to improve physical-psychological and social health in the Sri Lankan setup with minimal resources.
Objectives {7}
We hypothesize that improvement occurs in selected metabolic and physiological parameters in patients with type 2 diabetes following meditation, independent of standard care. We also hypothesize that these effects occur due to the reduction of stress hormones (cortisol), improvement of insulin resistance and improvement of autonomic dysfunction.
The general objective is to determine the effects of meditation on selected metabolic and physiological parameters in patients with type 2 diabetes by conducting an open-label randomized controlled clinical trial and investigating the possible mechanisms by which meditation affects these parameters.
Specific objectives are to determine the effects of meditation on glycaemic control, lipid profile and blood pressure, insulin resistance, 24 urinary cortisol, orocecal transit time using lactulose hydrogen breath test and cardiac autonomic functions. This will be done using standard cardiac autonomic reflex testing (CART), and further analysis of ECG recording in order to analyse heart rate variations(HRV) using Power Lab-8 Pro software.