Effect of Yoga on Glucose Control and Quality of Life in Patients of Prediabetes

Abstract

Objective:

The objective of this study was to evaluate effect of yoga on fasting plasma glucose (FPG), postprandial plasma glucose, and hemoglobin A1C (HbA1C) and also on quality of life (QoL).

Research Design and Methods:

This was a cohort study in which 100 diagnosed cases of prediabetes were recruited for doing specific yoga, and they themselves act as control for the study. The measurement and comparison of FPG, prandial plasma glucose (PPG), and HbA1C were done at three different time intervals, that is, baseline, 3 months, and at 6 months. The assessment of QoL was done using SF-36 scale.

Results:

One hundred prediabetic cases were selected for the study in which impaired fasting glucose (IFG) was present more in younger population compared to impaired glucose tolerance (IGT) and IFG plus IGT both of which are more prevalent in middle age group. The yoga therapy was found to have favorable effect on FPG, PPG, and HbA1C along with various anthropometry measures studied in this study. After adjusting correlation coefficient for various anthropometry measures, yoga was found to be effective for controlling glycemic parameters in prediabetics.

Conclusions:

Yoga is a type of exercise known to improve glycemic control by changing anthropometry measures, but our study aids in knowledge about the beneficial effect beyond this known fact through other mechanisms yet to be explored.

Introduction

Prediabetes also known as the state of the intermediate degree of hyperglycemia is associated with high risk of future conversion to diabetes. Various lifestyle modification studies have shown that lifestyle modification by targeting obesity and physical inactivity remains cornerstone therapy for diabetes prevention.¹ According to the recent ICMR-INDIAB study, the prevalence of prediabetes ranges from 6% to 14.7% in India.² Around 70% of individuals with prediabetes will develop diabetes in due course with an annual conversion rate of 5%–10% according to American Diabetes Association (ADA) expert panel.¹ In addition, it is said that if proper and timely interventions are taken then a similar proportion of subjects will revert to normoglycemia annually. Yoga, a form of lifestyle intervention, can be helpful in the prevention of further progression to diabetes mellitus and associated complications to occur. There are various studies conducted in the diabetic population to evaluate the effect of yoga in different regions of the world, particularly the United States, Europe, and India, but data with the prediabetic population are exiguous.³ This study was planned to investigate the effect of yoga on plasma glucose and quality of life (QoL) in prediabetic patients.

Research Design and Methods

One hundred prediabetic subjects were recruited from the Department of Endocrinology of Pt. B.D. Sharma PGIMS, Rohtak to observe the effect of yoga on plasma glucose and QoL. Prediabetes was diagnosed using the ADA criteria.⁴ The fasting plasma glucose (FPG) >100 and <126 mg/dL was taken as impaired fasting glucose (IFG), and a value of postprandial plasma glucose level >140 and <200 mg/dL after 75-gram oral glucose tolerance test (OGTT) was taken as impaired glucose tolerance (IGT). The ethical clearance was taken from Institutional Ethics Committee to conduct the study, and informed consent was taken from all participating subjects. Participants suffering from diabetes or any other chronic systemic illness, female subjects who are pregnant, breastfeeding, or planning a pregnancy, and those taking any lipid-lowering drugs, steroids, nicotinic acid, or other medications that cause dysglycemia were excluded from the study. Initial evaluation included a detailed history and clinical examination of the subjects to exclude any systemic diseases.

Anthropometric indices, including height (without shoes and socks), weight, waist circumference (WC), and hip circumference, were recorded for the subjects. Height was measured to the nearest 0.1 cm using a portable stadiometer and weight measured to the nearest 0.1 kg using calibrated platform scales. WC was measured to the nearest 0.1 cm at the midpoint between the subcostal margin and the margin of the supracristal plane. Hip circumference was measured to the nearest 0.1 cm around the thighs, at the height of the greater trochanter, with the patients in the standing position. Blood pressure was recorded after patients were made to sit and rest for at least half an hour. Blood pressure was recorded thrice at 5-min intervals in a sitting position in the nondominant arm, with the value to the nearest 2 mmHg, using a standard adult mercury sphygmomanometer. The mean of the three readings was taken as blood pressure. Visceral adiposity index (VAI)⁵ was calculated using age, body mass index (BMI), WC, serum triglycerides (TGs), and high-density lipoprotein cholesterol (HDL-C) levels. According to the International Diabetes Federation definition⁶ for the Indian population, for an individual to be defined as having the metabolic syndrome, he/she must be diagnosed as having central obesity defined as WC ≥90 cm in males or ≥80 cm in females plus any two of the following four factors: (1) TGs ≥150 mg/dL or specific treatment for this lipid abnormality; (2) HDL-C <40 mg/dL in males or <50 mg/dL in females or specific treatment for this lipid abnormality; (3) systolic blood pressure (SBP) ≥130 mmHg or diastolic blood pressure (DBP) ≥85 mmHg or treatment for previously diagnosed hypertension; (4) FPG ≥100 mg/dL or previously diagnosed type 2 diabetes.

All prediabetic subjects were asked to perform various yoga exercises for 6 months. Yoga therapy in this study was consisting of meditation and nine different yoga asanas, including regulated breathing practices-pranayama, seating poses-maundukasana, arthamatsyendrasana; inversions-halsana, vajrasana, prone poses-dhanurasana, bhujangasana, supine poses-pavanamuktasana, and standing postures-katichakrasana along with prayer in the form of omkar.⁷ All these yoga exercises were known to affect glucose tolerance favorably and were performed for 40 min every day. Subjects were trained to perform yoga in the hospital for 1 week under the direct supervision of a trained yoga instructor and then allowed to do the same for the rest 3 weeks of the month at home during which they were contacted telephonically. Next month they were again called to perform the same yoga asanas and pranayama for 1 week under the direct supervision and for the rest of the month at home and this cycle was repeated for a total duration of 3 months. After this cycle, participants were allowed to do yoga asanas and pranayama at home for the next 3 months, and they were contacted over the telephone to ensure their compliance. The assessment of the QoL was done using short-form health survey with 36 questions (SF-36), which assess physical and mental health status concerning eight health concepts that include physical functioning, role limitations due to physical health, bodily pain, general health perceptions, vitality (energy/fatigue), social functioning, role limitations due to emotional health, and general mental health (psychological distress/well-being).⁸ The scale score ranged from 0 to 100 for every subscale, with a higher outcome meaning a better health status. To assess the effect of yoga, various anthropometric and biochemical parameters and SF-36 questionnaires were recorded at baseline and 3 and 6 months of yoga. Analyses were performed using SPSS software, Version 20.0 and P < 0.05 being considered significant.

Results

Out of 100 prediabetic subjects, 66 were female and 34 were male. The mean age of the cases included was 41.57 ± 10.395 years. Yoga therapy was found to have a significant favorable effect on various parameters as shown in Table 1. Among 100 prediabetic subjects, 19 (19%), 16 (16%), and 65 (65%) were having IFG, IGT, and both IFG and IGT, respectively. The mean reduction in FPG was 9.63 ± 3.97 mg/dL, 2.0 ± 1.9 mg/dL, and 8.78 ± 5.98 mg/dL at 6 months of Yoga therapy with significant P value (<0.001) in IFG, IGT, and IFG+IGT groups, respectively. There was a significant reduction in 2 hr OGTT plasma glucose values by 4.05 ± 2.53 mg/dL, 10.5 ± 4.01 mg/dL, and 11.29 ± 8.92 mg/dL at 6 months of Yoga therapy in IFG, IGT, and IFG+IGT groups, respectively (P value <0.001). The mean hemoglobin A1C (HbA1c) levels decreased significantly from a baseline value of 6.055% ± 0.1930% to 5.806% ± 0.2577% at 6 months (P value <0.001). The present study showed that among 19 IFG and 16 IGT subjects at baseline, 6 (31.5%) and 3 (18.7%) subjects, respectively, converted to euglycemia at 6 months of Yoga therapy. Among 65 IFG+IGT subjects at baseline, 2 (3.2%) subjects become euglycemic, 7 (10.7%) subjects converted from IFG+IGT to IFG alone, and 12 (18.4%) subjects converted from IFG+IGT to IGT alone, respectively, at 6 months of Yoga therapy. There was also significant improvement in blood pressure, as well as lipid profile, as shown in Table 1. The Tg/HDL ratio was 4.134 ± 2.5 at beginning of study, which reduced to 3.05 ± 2.11 at the end of study with significant P value (< 0.001). At baseline, metabolic syndrome was present in 80 subjects (80%). After performing yoga, prevalence of metabolic syndrome reduced to 47 subjects (47%) at 6 months with significant P value (<0.001). The QoL assessed using the SF-36 scale showed improvement in each domain of both physical and mental health scores, which persist through the whole study period with a significant P value (<0.001). Improvement in glycemic control was best correlated with VAI improvement. The correlation coefficient between FPG, 2 hr OGTT PG, and HbA1c and VAI was 0.617, 0.652, 0.503, respectively, at 6 months of Yoga therapy with a significant P value (<0.001). After 6 months of yoga therapy, dyslipidemia was the most improved component among all components of metabolic syndrome with a correlation coefficient of 0.462 and −0.443 for TG and HDL, respectively, with significant P value (<0.001). On multivariate analysis, Yoga itself was found to be associated with improvement in glycemic control and QoL (Table 2).

Table 1.

Comparison of Anthropometric Variables, Lipid Profile, and Blood Pressure at Baseline and at 3 and 6 Months

Variable	At Baseline		At 3 months		At 6 months		P
Variable	Mean	SD	Mean	SD	Mean	SD	P
Wt (in kg)	68.23	8.17	66.05	8.44	64.47	8.67	<0.001
WC (in cm)
Male n < 90 cm	92.70	7.03	89.94	7.667	89.64	7.66	<0.001
Female n < 80 cm	93.11	8.44	90.80	8.667	88.47	7.944	<0.001
HC (in cm)	104.43	9.420	101.97	10.12	100.67	11.125	<0.001
W/H ratio	0.89	0.06	0.89	0.062	0.89	0.065	0.833
W/Ht ratio	0.57	0.05	0.56	0.063	0.55	0.065	<0.001
BMI (kg/m²)	25.96	3.69	25.15	3.92	24.56	4.057	<0.001
BFC (%)	33.45	6.06	31.18	5.72	29.48	5.74	<0.001
VAI Normal-1	3.19	1.93	2.67	1.60	2.39	1.66	<0.001
TG (mg/dL) Normal <150 mg/dL	157.19	51.447	146.84	47.035	138.07	44.440	<0.001
HDL (mg/dL) Male >40 mg/dL Female >50 mg/dL	42.49	10.516	46.45	9.000	49.77	8.458	<0.001
LDL (mg/dL)	99.55	23.227	93.29	21.758	88.39	22.541	<0.001
SBP (mmHg)	126.63	8.650	122.97	7.842	121.35	8.040	<0.001
DBP (mmHg)	81.72	6.685	79.38	5.546	78.38	5.747	<0.001

Wt, weight, W/H, waist/hip, W/Ht, waist/height.

BFC, body fat composition; BMI, body mass index; DBP, diastolic blood pressure; HC, hip circumference; HDL, high-density lipoprotein; LDL, low density lipid; SBP, systolic blood pressure; SD, standard deviation; TG, triglyceride; VAI, visceral adiposity index; WC, waist circumference.

Table 2.

Multivariate Regression Analysis for Glycemic Parameters and Quality of Life

Multivariate regression	3 months (adjusted R² )	P	6 months (adjusted R² )	P
FPG	0.213	<0.001	0.431	<0.001
PPG	0.395	<0.001	0.554	<0.001
HbA1c	0.192	<0.001	0.331	<0.001
QoL	0.153	<0.001	0.251	<0.001

FPG, fasting plasma glucose; HbA1c, hemoglobin A1C; PPG, prandial plasma glucose; QoL, quality of life.

Discussion

The present study showed that yoga has a favorable effect on glycemic, various anthropometric, and metabolic parameters of prediabetic subjects. Overall, 9 patients reverted to euglycemia from IFG or IGT with 6 months of Yoga therapy. Among those 65 patients having IFG+IGT combined, 19 patients go back to a better glycemic category, that is, to either IFG or IGT alone, while 2 patients reverted to euglycemia. The prevalence of metabolic syndrome also regressed significantly after 6 months of Yoga therapy, and the benefit was observed more in males of 40–49 years age group. Obesity is now emerging as major health issue in developing countries, which may be also part of metabolic syndrome having characteristic of insulin resistance. Tg/HDL ratio with cutoff value of 3.0 is a recently developed marker for insulin resistance.⁹ In current study, there is significant reduction in Tg/HDL ratio reflecting in decreased prevalence of metabolic syndrome. QoL showed significant improvement in every domain of both physical and mental health scores.

Many studies were revealing the effect of exercise on diabetic occurrence in patients having high-risk metabolic profile. Among them, The Finnish Diabetes Prevention Study (FDPS)¹⁰ aims to assess the utility of lifestyle intervention and diet change in preventing or delaying diabetes mellitus in IGT individuals and also on various atherosclerotic risk factors. This study showed a 58% reduction in the incidence of diabetes and improvement in various modifiable atherosclerotic risk factors compared with those who received general advice in individuals with IGT. Similar results were also obtained in the Diabetes Prevention Program (DPP)¹¹ in which patients were subjected to lifestyle intervention, including nutrition, exercise, and behavioral weight control. However, Yoga which is also a form of lifestyle intervention has not been studied extensively in the prediabetic population. Hedge et al.¹² studied the effect of a community-based yoga intervention for 3 months on oxidative stress and glycemic parameters in 29 prediabetics. They found a favorable effect of yoga on oxidative stress and IFG only. Similarly, Venugopal et al.¹³ found a favorable effect of 10 days of yoga therapy on FPG alone. McDermott et al.¹⁴ conducted a randomized control trial of 2 months in 41 high-risk participants for diabetes mellitus to assess the changes in BMI, WC, FPG, postprandial plasma glucose, insulin, insulin resistance, blood pressure, and cholesterol. Out of 40 subjects, 21 participants performed yoga for 2 months, while the remaining 19 participants were subjected to 30 min of walking only. All of these subjects were also given counseling session. Yoga group participants were allowed to choose any three asanas among different asanas available for each posture. When both groups were compared, yoga participants were found to have significantly greater reductions in weight, WC, and BMI compared to the control group. They observed no significant between-group differences in FPG, prandial plasma glucose (PPG), insulin, insulin resistance, blood pressure, cholesterol, or psychological measures of well-being. Blood pressure and total cholesterol were significantly reduced in both groups. Yang and James¹⁵ studied 23 adults who were at high risk for developing type 2 diabetes utilizing 3 months of the yoga program. Among 23 participants only 13 members were assigned to yoga group and remaining to biweekly health education. Compared to the education group, the yoga group revealed a pattern of improvements in weight, SBP, DBP, insulin, total cholesterol, TGs, and exercise self-efficacy, while fasting glucose level, LDL, and HDL reflected small or no changes.

In the present study favorable effect of Yoga was observed not only on glycemic (both FPG and postprandial plasma glucose [PPPG]) and anthropometry variables but also on various metabolic parameters like blood pressure and lipid profile. VAI⁵ correlated better with visceral fat dysfunction, insulin resistance, and cardiometabolic risk than BMI and WC as it includes anthropometric measures, as well as metabolic parameters. None of the studies in the past has studied the effect of various lifestyle interventions, including yoga on improvement in VAI. In the present study improvement in VAI correlated best with improvement in FPG, 2 hr OGTT PG, and HbA1c.

The word Yoga is derived from the Sanskrit word “Yuj” meaning the union of the body, breath, and mind.¹⁶ Regular practice of yoga enhances awareness of mind and body, which is needed in the self-management of diet and can improve the degree of exercise; self-efficacy for physical activity remains a keystone in management of prediabetes and diabetes.¹⁷ It is proven in a few studies that regular and continuous yoga exercise is responsible for improving serum lipid concentrations, adipose tissue, and metabolic syndrome factors because of refinement in body composition.^18,19 The positive benefit of Yoga can be explained by the involvement of at least two major pathways; the hypothalamic-pituitary-adrenal axis or by reducing the activation of the sympathoadrenal system that involved in insulin resistance and hepatic glucose production.²⁰ Both these pathways are involved in altering insulin resistance and hepatic glucose output. In the present study, on multivariate analysis, yoga itself was found to be associated with improvement in FPG, PPG, HbA1c, and QoL. It was observed that 43%, 55%, and 33% of the variance in FPG, 2 hr OGTT plasma glucose, and HbA1c, respectively, and 25% variance in QoL when assessed using SF-36 scale could be explained by 6 months of Yoga therapy alone after adjusting for various anthropometry variables with significant P value (<0.001). Till now, the exact fundamental basis which is responsible for the beneficial effect of yoga on glycemic parameters beyond changing body composition remains elusive. Recent trials show that yoga therapy results in decreased perception of stress, elevates mood, reduction in catecholamine and cortisol levels, and improvement in blood pressure along with sympathetic parameters in healthy adults, as well as in diabetic patients.^21,22 All these mechanisms result in shifting of autonomic balance from primarily sympathetic to parasympathetic system and finally enhancing parasympathetic output. The net balance of neuroendocrine and hemodynamic changes produced by yoga therapy may be responsible for the beneficial effect on metabolic parameters.

To conclude with, Yoga therapy is an effective and acceptable lifestyle intervention for improving body composition, glycemic parameters, metabolic parameters, and QoL in patients with prediabetes. However, the results of this study need to be validated by further studies involving a larger number of participants across different regions of the country.

Footnotes

Author Disclosure Statement

No conflicting financial interests exist.

Funding Information

No funding was received for this work.

References

Nathan

, Davidson

, DeFronzo

, et al. Impaired fasting glucose and impaired glucose tolerance: Implications for care. Diabetes care. U S Natl Libr Med, 2007; 30:753–759.

Anjana

, Pradeepa

, Deepa

, et al. ICMR-INDIAB Collaborative Study Group. Diabetologia, 2011; 54:3022–3027.

Monroe

, Power

, Comer

, et al. Yoga therapy for NIDDM; a controlled trial. J Complement Med Res, 1992; 6:66–68.

American Diabetes Association. Diagnosis and classification of diabetes mellitus. Diabetes Care, 2010; 33(Suppl 1):S62–S69.

Amato

, Giordano

, Galia

, et al. Visceral adiposity index: A reliable indicator of visceral fat function associated with cardiometabolic risk. Diabetes Care, 2010; 920–922.

Alberti

, Zimmet

, Shaw

, et al. The metabolic syndrome—A new worldwide definition. Lancet, 2005; 366:1059–1062.

Raveendran

, Deshpandae

, Joshi

. Therapeutic role of yoga in type 2 diabetes. Endocrinol Metab (Seoul), 2018; 33:307–317.

Ware

Jr ., Sherbourne

. The MOS 36-item short-form health survey (SF-36). I. Conceptual framework and item selection. Med Care, 1992; 30:473–483.

Marotta

, Russo

, Ferrara

. Triglyceride-to-HDL-cholesterol ratio and metabolic syndrome as contributors to cardiovascular risk in overweight patients. Obesity (Silver Spring), 2010; 18:1608–1613.

10.

Tuomilehto

, Lindström

, Eriksson

, et al. Prevention of type 2 diabetes mellitus by changes in lifestyle among subjects with impaired glucose tolerance. N Engl J Med, 2001; 344:1343–1350.

11.

Knowler

, Barrett-Connor

, Fowler

. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med, 2002; 346:393–403.

12.

Hegde

, Adhikari

, Shetty

, et al. Effect of community-based yoga intervention on oxidative stress and glycemic parameters in prediabetes: A randomized controlled trial. Complement Ther Med, 2013; 21:571–576.

13.

Venugopal

, Rathi

, Raghuram

. Effect of short-term yoga-based lifestyle intervention on plasma glucose levels in individuals with diabetes and pre-diabetes in the community. Diabetes Metab Syndr, 2017; 11 (Suppl 2):S597–S599.

14.

McDermott

, Rao

, Nagarathna

, et al. A yoga intervention for type 2 diabetes risk reduction: A pilot randomized controlled trial. BMC Complement Altern Med, 2014; 14:212.

15.

Yang

, James

. Yoga, as a transitional platform to more active lifestyle: A 6-month pilot study in the USA. Health Promot Int, 2016; 31:423–429.

16.

DiStasio

. Integrating yoga into cancer care. Clin J Oncol Nurs, 2008; 12:125–130.

17.

Zope

, Zope

. Sudarshan kriya yoga: Breathing for health. Int J Yoga, 2013; 6:4–10.

18.

Lee

, Kim

. Effects of hatha yoga exercise on serum leptin and metabolic syndrome factors in menopause obese middle-aged women. Korean J Life Sci, 2010; 20:1100–1106.

19.

Sivasankaran

, Pollard-Quintner

, Sachdeva

, et al. The effect of a six-week program of yoga and meditation on brachial artery reactivity: Do psychosocial interventions affect vascular tone?. Clin Cardiol, 2006; 29:393–398.

20.

Björntorp

, Holm

, Rosmond

. Hypothalamic arousal, insulin resistance and type 2 diabetes mellitus. Diabet Med, 1999; 16:373–383.

21.

de G R Hansen

, Innes

. The benefits of yoga for adults with type 2 diabetes: A review of the evidence and call for a collaborative, integrated research initiative. Int J Yoga Therap, 2013; 23:71–83.

22.

Innes

, Bourguignon

, Taylor

. Risk indices associated with the insulin resistance syndrome, cardiovascular disease, and possible protection with yoga: A systematic review. J Am Board Fam Pract, 2005; 18:491–519.