Background and Clinical Problem
Practitioners of meditation have long believed in its ability to treat stress and chronic disease. The physiological basis of this belief has never been fully described, but as current research continues to reveal the intricacies of neuro-endocrine pathways, meditation, yoga, and other mind-body therapies are considered to be promising options in the treatment of diabetes.
The prevalence of diabetes is increasing dramatically worldwide.1 Negative effects of physiological and emotional stress on blood glucose control have been described in the literature.2,3 Mind-body therapies, such as meditation, yoga, qi-gong, and other relaxation techniques, have been studied in diabetes as a means of decreasing stress-related hyperglycemia.4–8 The objective of many mind-body therapies is to facilitate attainment of a physiological state that counteracts the stress response and develops into a permanent set of traits among practitioners.
Physiological and emotional stress activate neuro-endocrine and sympathetic pathways via the hypothalamic-pituitary-adrenal axis and medullary adrenal sympathetic system.9,10 Circulating catecholamines and glucocorticoids affect the structure and function of a variety of tissues and induce inflammatory cytokines that lead to increased glucagon production and decreased uptake and disposal of glucose in peripheral muscles.11 Cytokines, primarily interleukin 6, have been strongly implicated in oxidative stress and inflammatory processes that lead to insulin resistance and vascular complications.11–13
The relaxation response promotes regulation of cortisol and other stress hormones.14 Structured programs of meditation, such as Transcendental Meditation and Mindfulness-Based Stress Reduction (MBSR), train participants in focused attention and diaphragmatic breathing to invoke this response. Other relaxation therapies involve progressive muscle relaxation, biofeedback, and a variety of behavioral stress management techniques, such as guided imagery.
Yoga is a traditional Indian practice that includes diaphragmatic breathing and asanas (body postures that promote physical comfort and mental composure). Yoga experts believe that some asanas exert positive effects on various endocrine glands.15 Qi-gong is an ancient Chinese form of “moving meditation” similar to t'ai chi that combines slow diaphragmatic breathing with spiral and circular body movements.16
K.M. is a 57-year-old black woman with hypertension, hyperlipidemia, and a 5-year history of type 2 diabetes treated with metformin and a sulfonylurea who presents for follow-up of diabetes. Her A1C has been > 7.5% for the past year. Her serum creatinine is noted to have increased to 1.6 mg/dl since the last appointment with her primary care provider. She complains of a lot of stress at home. She has been intolerant of thiazolidinedione medications because of edema and weight gain. She has not been able to lose weight despite multiple attempts at dieting and has difficulty exercising because of pain related to osteoarthritis in her hips and knees. Her health insurance does not cover many newer diabetes medications, and she cannot afford high-cost medications. She is fearful of needles and wants to avoid injections.
Physical exam reveals a BMI of 32 kg/m2 and blood pressure of 138/84 mmHg. Acanthosis nigricans is noted at the skin folds of her posterior neck. Her waist circumference is 40 inches. Her heart and lung examination are normal, and her abdomen is obese and nontender without masses. The remainder of her physical examination is unremarkable. Pertinent laboratory values include A1C of 7.8%, fasting plasma glucose (FPG) of 168 mg/dl, and serum creatinine of 1.6 mg/dl.
Are there any cost-effective, nonpharmacological therapies in addition to weight loss and exercise that may help improve glycemic control in adults with diabetes?
Population: adults with diabetes
Intervention: meditative therapies for glycemic control
Comparison: nonmeditative therapies for glycemic control
Outcomes of interest: A1C and FPG
To conduct an integrated review of the literature, three databases (Medline, CINAHL, and AMED) were queried using the search terms meditation, yoga, relaxation techniques, breathing exercises, diabetes type 1 or type 2, hyperinsulinism, and hemoglobin A, glycosylated. This search yielded 20 citations written in English between 1974 and 2007. Articles written in English, using adult samples, and published after 1985 were reviewed. Before 1985, most of the work done in this area was qualitative or anecdotal. Articles were retrieved from the Health Science Library System at the University of Pittsburgh in Pennsylvania.
The search was limited to two dependent variables: A1C and FPG. A1C is an accepted measure of glycemic control in diabetes that estimates the average blood glucose level from the previous 3 months. The American Diabetes Association (ADA) recommends maintaining an A1C < 7% to decrease the risk of microvascular complications. FPG provides a measure of glycemic control in terms of pancreatic ⊠-cell function and insulin resistance.16
Results and Critical Appraisal
All study interventions took place in outpatient settings without interruption or change in the participants' current diabetes therapy. Improvements in A1C consistently correlated with improvements in FPG. No adverse effects were reported in any of the studies. All but one study were performed in adults with type 2 diabetes, and one study was done in adults with type 1 diabetes. Additionally, all but one of the studies used a group intervention; however, possible cohort effects were not addressed by the authors. A comparison of the studies is found in Table 1.
Three observational studies performed in India using multi-modality yoga interventions observed positive improvements in glycemic control, prompting the investigators to conclude that the physiological mechanism should be further explored.4–7 A 2007 prospective observational pilot study on MBSR in type 2 diabetes demonstrated decreased A1C and psychological distress independent of weight loss and lifestyle modification.17 This was the first study to investigate MBSR in a cohort of individuals with diabetes.
Secondary analysis of a randomized controlled trial (RCT) of 60 adults with type 2 diabetes was performed by Elder et al. using whole-systems analysis to evaluate a traditional multi-modality Indian Ayurvedic intervention protocol that incorporated daily meditation. The Vedic intervention was associated with decreased A1C and mean FPG only in participants whose baseline A1C was > 6.5%.18 The results of this study were confounded by the other independent variables that included exercise, diet, and an herbal supplement.
Five other small RCTs showed trends toward positive improvements in A1C and FPG.7,8,19–21 Control groups were variable and often included a second intervention, such as general health education, diabetes education, or exercise. A South African study that compared an intervention of education plus aerobic exercise to one of education plus relaxation therapy in Black African women showed small but similar improvements in A1C in both groups, which the authors attributed to study effect.20
Studies of relaxation techniques with and without biofeedback had mixed results. Surwit et al. studied 108 subjects with type 2 diabetes for 1 year following a five-session group intervention of relaxation therapy plus diabetes education. There was a 0.5% reduction in A1C relative to control subjects, with 32% of the treatment group having a ≥ 1% reduction in A1C compared to 12% of control subjects.21 Reductions in A1C of as little as 0.6% have been associated with a significant reduction in risk of complications in type 2 diabetes.22
Another study of relaxation therapy plus biofeedback demonstrated improved glycemic control that was sustained for 3 months and was associated with decreased depression and anxiety scores.19 However, a Swedish study of relaxation therapy in adults with type 1 diabetes failed to show an improvement in A1C despite improvement in mood.23 Similar findings were reported in a RCT of relaxation therapy plus biofeedback in which there was no improvement in FPG or other measures of glucose tolerance despite reductions in psychological and physiological stress.24
Improvements in A1C with qi-gong were associated with improved mood and decreased C-peptide.8 The authors suggest that the observed reduction in C-peptide may suggest an underlying mechanism of decreased insulin resistance with qi-gong.
Summary Evidence Grading System for Clinical Practice Recommendations
Based on the ADA evidence grading system for clinical practice recommendations, in which A is clear evidence from RTCs, B is supportive evidence from well-conducted cohort studies, C is from poorly controlled studies, and E is from expert consensus or clinical experience, four studies met criteria for level B and one study met criteria for level C. Although seven studies met most of the criteria for level A, none were large multi-center trials. All the RCTs reviewed had relatively small sample sizes and lacked scientific rigor, limiting their ability to make generalizable conclusions but provided convincing evidence for further inquiry. Four of eight RCTs reviewed for this article compared the effects of meditative therapies to those of usual care using conventional treatment regimens. Four others were confounded by additional nonmeditative interventions. Larger RCTs that investigate the mechanisms of action and compare effects of specific mind-body interventions on diabetes control are warranted.
Case Study Revisited
Because K.M.'s serum creatinine had increased above 1.4 mg/dl, metformin was discontinued. Her sulfonylurea dose was increased. She was referred to a registered dietitian for medical nutrition therapy and was advised to enroll in a yoga class being offered at the YWCA in her neighborhood. She was asked to return for follow-up in 3 months. If her A1C remains > 7%, further adjustments to her diabetes medication regimen will be considered.
Clinical Question Revisited/Implications for Practice
There are data to suggest that mind-body therapies may have an overall positive effect on glucose control. However, there is currently no conclusive evidence to support this hypothesis. No adverse effects were reported in any of the studies that were reviewed. Based on these studies, it appears that yoga, meditation, qi-gong, and relaxation therapy are safe techniques that may be of benefit in the treatment of diabetes but require further study.
Meditation, yoga, and other mind-body therapies are becoming more popular and accessible through local health clubs and wellness centers. These therapies may represent cost-effective self-care strategies for improving glucose control through regulation of neuro-endocrine processes that impair glucose metabolism. Until more research is available and the effects of these techniques are more clearly defined, mind-body therapies could be recommended only as potentially helpful adjuncts to conventional diabetes therapy.
Editor's note: The articles published in this department present patient cases using an evidence-based practice framework presented with “PICO” components: population, intervention, comparison, and outcome; a description of the search strategy employed for the integrative review; a summary of the results and critical appraisal of the search; and an evaluation of the scientific and medical evidence base for recommendations.
Monica M. DiNardo, MSN, CRNP, CDE, is a pre-doctoral student at the University of Pittsburgh School of Nursing in Pennsylvania.
- American Diabetes Association