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1

The Effect of Gymnema sylvestre and Camelia sinensis on Patients with

Type 2 Diabetes Mellitus

Nani Da*

, Siti Suhaila MYa, Faridah MZ

a and Wan Zahiruddin WM

b

aDepartment of Family Medicine, School of Medical Sciences, Health Campus, Universiti Sains Malaysia,

16150 Kubang Kerian, Kelantan, Malaysia

bDepartment of Community Medicine, School of Medical Sciences, Health Campus, Universiti Sains Malaysia,

16150 Kubang Kerian, Kelantan, Malaysia

*Corresponding Author: drnani@usm.my

_________________________________________________________________________________

ABSTRACT: GlucosCare Herbal Tea (GCT) consists of two plants namely the Gymnema

sylvestre and Camellia sinensis. The leaves of these plants are used as anti-obesity,

hypoglycemic, hypolipidemic and anti-oxidant agents. The present study is an open label,

single-arm clinical trial involving 67 diabetic patients with glycosylated hemoglobin

(HbA1c) between 7 and 10% on oral hypoglycaemic agents only. HbA1c, serum insulin, total

cholesterol, fasting blood sugar (FBS), body mass index (BMI), and blood pressure (BP)

were measured at the baseline at each follow-up visit. The tea used in this study was

consumed three times daily for three months with four follow-up visits at 2, 4, 8 and 12

weeks. The 64 subjects who completed this study were predominantly females (n=41) with

an average age of 50 years old, Malay and employed. The primary outcome for this study is

the change in HbA1c level at week-12. The secondary outcomes are the changes in insulin

level, body weight, fasting blood sugar, lipid profile, waist circumference and blood pressure

at week-12. At week-12, the HbA1c has significantly reduced by 1.1 (95%CI 0.84 - 1.37).

The FBS measurements significantly reduced between each visit [F (2.8, 178.6) = 5.241;

p=0.002] especially after 8 and 12 weeks of consumption. No significant changes were

observed in serum insulin, total cholesterol, BMI and BP. GlucosCare Herbal Tea has been

shown to have favorable effects on HbA1c and FBS in patients with uncontrolled Type 2

Diabetes Mellitus after 12 weeks. A randomize control clinical trial is recommended for

future study to show the effectiveness of GlucosCare Herbal Tea.

2

Keywords: Camellia sinensis, Gymnema sylvester, herbal tea, type 2 diabetes mellitus

Introduction

The increment in the prevalence of diabetes has become a major global health problem

(Letchuman et al., 2010). In Malaysia, the prevalence of the diabetes mellitus has increased

from 11.6% in 2006 to 15.2% in 2011 (MI, 2013). Factors contributing to this alarming

phenomenon include growth in aging population, increasing prevalence of obesity along with

reduction in physical activity due to urbanization (Wild et al., 2004). Currently, oral

hypoglycemic drug and insulin are still the main treatment for patients with diabetes mellitus

with the purpose to lower blood glucose level and to prevent complications due to the

disease. However, patients of diabetes mellitus are not satisfied with the effectiveness of

current medication (Kusumawati et al., 2013). The patients therefore turn to and favor the use

of supplements or other alternative medicine.

One form of herbal supplement preparation that is popular in treating diabetes mellitus is tea.

Studies have demonstrated its ability to reduce the risk of getting chronic illnesses such as

type 2 diabetes mellitus and cardiovascular diseases (Jing et al., 2009; Zaveri, 2006). Tea

from the plant of Camellia sinensis (CS) is consumed in different parts of the world as green,

black, or oolong tea. Different processes of the CS leaves produce different kind of teas. To produce

green tea, the fresh harvested leaves are rapidly steamed to inactivate the enzyme thus preventing the

fermentation process. The production of black and oolong tea on the other hand will need the fresh

leaves to undergo the fermentation and oxidation processes. This will lead to changes in the tea color

and flavor as well as the polyphenol and caffeine contents (Hayat et al., 2015).

There are significant effects on human health with the consumption of green tea (Cabrera et

al., 2006). It has the ability to reduce blood glucose level (Maruyama et al., 2009) especially

the fasting blood glucose level (Polychronopoulos et al., 2008). Green tea contains many

polyphenols (Higdon and Frei, 2003) including the catechins’ (Osada et al., 2001). These

polyphenol especially epicatechin gallate and epigallocatechin gallate (EGCG) will inhibit

the Na+/glucose transporter and SGLT1 activity thus reducing the glucose uptake in the

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intestine (Kobayashi et al., 2000). EGCG, which is abundantly found in green tea, may

increase the insulin sensitivity and decrease the hepatic glucose production in liver (Potenza

et al., 2007). Due to the benefic effect, EGCG has been suggested to have a potential role as

anti-diabetic agent (Waltner-Law et al., 2002).

Catechins and other polyphenols may also act as anti-obesity (Kao et al., 2006), anti-oxidant,

anti-viral and anti-inflammatory agents besides being reported to have anti-cavity properties

(Mishra et al., 2013).These compounds were also said to be useful for the maintenance of

cardiovascular and metabolic health (Wolfram, 2007).

Gymnema sylvestre (GS) is another natural herb used in this trial. It grows in tropical forests

of the central and southern parts of India (Bone, 2002). It is a potent anti-diabetic plant used

especially in the treatment of asthma, eye problem and family planning. It also acts as anti-

microbial and anti-hypercholesterolemia agent besides being reported to possess glucose

suppressing activity (Kanetkar et al., 2007). The main constituent of GS is gymnemic acid

but the mode of action is unknown; the possible theories are it could stimulate the

regeneration of islet cells, induce the secretion of insulin, increase the utilization of glucose

and inhibit the glucose absorption from intestine (Kanetkar et al., 2007). It also could

suppress the sweet taste sensation (Porchezhian and Dobriyal, 2003). In animal studies, GS

extract was observed to improve beta cell function in diabetic rats. It has the ability to

increase fasting blood glucose and serum insulin levels (Shanmugasundaram et al., 1990a) .

There are many studies done on diabetic patients or animals using single herb trial (Baskaran

et al., 1990, Shanmugasundaram et al., 1990b, Fukino et al., 2008). However, in this trial, a

combination of GS and CS referred to as GlucosCare Herbal Tea (GHT) was used to give a

synergistically effect in blocking the sugar absorption thus influenced the levels of HbA1c ,

fasting blood sugar, serum insulin, total cholesterol, body weight and blood pressure in

subjects with Type 2 Diabetes Mellitus (T2DM).

4

Materials and Methods

Study design and setting

This is an open label, single-arm interventional study for a period of 12 weeks among

patients with T2DM whose HbA1c levels are between 7% and 10% at Hospital Universiti

Sains Malaysia (HUSM). Convenient sampling was applied and the recruitment was done at

Klinik Rawatan Keluarga (KRK) at Hospital USM. Figure 1 illustrates the flow of the study.

Assess case notes of T2DM patients attending HUSM

Type 2 diabetic patients who fulfill inclusion and exclusion criteria will be invited to participate

Written informed consent taken

Assessment schedule

Data collection

Data analysis

Report

Figure 1: Study flow chart

V1

0/52 HbA1c

FBS

Serum

insulin

FLP

FBC

RFT

LFT

WT

BP

V3

1/12

FBS

WT

BP

V2

2/52

FBS

WT

BP

V4

2/12

FBS

WT

BP

V5

3/12

HbA1c

FBS

Serum

insulin

FLP

FBC

LFT

RFT

WT

BP

3 months (12 weeks)

Patients take

“GlucosCare Tea”

3 times per day

Parameters assessed;

HbA1c

Fasting blood glucose (FBS)

Serum insulin

Fasting lipid profiles (TC, TG, LDL, HDL

Liver function test (LFT)

Renal function test (RFT)

Haemogram (Hb, TW, Plateletes)

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Participants

The participants were adult, 18 years and above, with uncontrolled T2DM (indicated by the

reading of HbA1c between 7 and 10% within the last three months). Other inclusion criteria

are: patients who are treated with oral hypoglycemic agents only, agree to participate in the

study and agree not to take other herbal supplements throughout the study duration. The

study excluded those with severe diabetic complications: end-stage renal diseases,

proliferative retinopathy, history of stroke, leg amputation or ischemic heart disease,

pregnancy and type I diabetes mellitus.

This study also excluded participants who are on insulin therapy, taking regular herbal or

other nutritional supplements in the last three months, or has alteration in their diabetic

regime throughout the study period. Selected participants who were found to be in non-

compliance with the study's follow up i.e. fail to drink the tea three times a day, were also

excluded. The selected patients were instructed to continue with their current prescribed

medication. The importance of compliance to medication, diet control, regular exercise and

the tea regime was emphasized to the participants during every follow up visit.

Sample size

A sample size of 69 was needed, with the considering of a 20 % drop out, and to achieve a

study power of 90% and significance level of 0.05 for the detection of 0.5 decreases in the

HbA1c after three months. The standard deviation of 1.12 was estimated from the study by

Agarwal et al. (2005).

Study agent

GCT is produced by GlucosCare International Pte Ltd in Singapore and is marketed by

GlucosCare (Malaysia) Sdn Bhd in Kuala Lumpur. This natural herbal tea is a

commercialized product and available in local and international markets for more than 10

6

years. This product is approved by the Malaysia Ministry of Health, with reference number of

MAL 06030937TC.

In this study, the patients were instructed to take 2.5 g of tea sachet three times per day after

meal. Each tea bag (2.5 g) contains GS (1.5 g) and CS (1.0 g). The tea bag was to be steeped

in 250 ml of boiling water for one minute.

There is no efficacy study done on this product to see the response of the product on HbA1c

level. Furthermore, the product is commonly taken by the consumers as beverages and it is

registered as Traditional Medicine in both Singapore and Malaysia. The dosage for each

ingredient is based on the real usage by centuries old formulation.

The toxicity study on GlucosCare Herbal Tea was previously conducted by SGS Hong Kong

Ltd Healthcare and Pharmaceutical Service. Twenty mice weighing between 18 g to 20 g

were administered at a dose of 250 g/kg based on the Maximal Tolerance Dosage (MTD)

Method recommended by Guidelines of New Drug Pre-clinical study. This was followed by a

7-day observation period. The dose was about 3000 folds over the recommended human daily

dose. All animal survived at the end of the study period with normal body weight gain and

food consumption. In conclusion, no adverse toxic effects were exerted on mice that were

administered with GlucosCare Tea at 250 g/kg.

The trial dose on animals (g/kg body weight) is used to calculate the equivalent dose for

human [Human Equivalent dose (HED)] by using the following formula:

Human Equivalent dose (HED) in mg/kg = Animal Dose (g/kg) x Animal “Km”

Human “Km”

(Reigner and Blesch, 2002)

Km is a correction factor reflecting the relationship between bodyweight and body surface

area. For a typical adult (body weigh 60 kg, body surface area 1.6 m2), Km is 37. For the

most often used laboratory animal species the average Kms are as follows : mouse 3, rat 6,

guinea pig 8, rabbit 12 and dog 20 (Reigner and Blesch, 2002).

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The first step was to determine animal dose (mg/kg). Previous animal study indicated that

GS is safe at the maximum dose of 250 g/kg with a concentration of 0.25 g/ml (MingTammy,

2005). The extract was administered orally to each mouse at 1 mg/g bodyweight daily. The

dose was tested and proven to be safe and nontoxic (MingTammy, 2005).

Standard dose used for administration on animal is 1 ml/1g (MingTammy, 2005). In 100 ml

of extraction there is 250 g of CS and GS, therefore, 1 ml contains about 2.5 g of CS and GS

extract. Hence, the animal dose was 2.5 g/kg. Next step was to incorporate the animal dose

of 2.5 g/kg into the formula:

Human Equivalent Dose (HED in mg/kg) = 2.5 g/kg x 3 Mice Km

37 Human Km

= 0.2 g/kg

Therefore, for human with an average weight of 60 kg: 0.2 g/kg x 60 kg = 12.2 g is the

dosage amount. Looking at the calculation, the patient should take a total of 7.5 g GlucosCare

product per day. The study amount is considered lower compared to the dosage in the toxicity

study. Unfortunately, there is no no-observed-adverse-effect-level (NOAEL) of GlucosCare

stated in the report.

Study procedures

Patients who fit the requirements were identified. Upon agreeing to participate in the study,

the patients were asked to sign the pertaining consent form. They were also given an

appointment date for visit 1. All visits were done in the morning and subjects were instructed

to fast for 8 hours prior to each visit while taking their medication as usual.

During visit 1, the demographic data and background medical history were recorded.

Physical examinations were also conducted. Weight and height measurements were taken

followed by the collection of 10 ml blood using sterile technique for HbA1c, fasting blood

glucose (FBS), serum insulin and, fasting lipid profile (FLP) measurements. Full blood count

8

(FBC), renal function test (RFT) and liver function test (LFT) were done to evaluate toxicity

changes due to the study agent. The blood samples were sent to a private laboratory for

analysis.

Subjects were explained on the preparation of GCT which is to soak one tea sachet in 250 ml

of hot water for 1 minute and to consume the whole amount of the prepared tea with every

main meal three times per day. At the same time patients were instructed to continue with

their current prescribed medication and they were advised to report any symptom or side

effect to the researchers.

Follow up

For the subsequent visits (visit 2, 3 and 4): subjects were assessed for any side effects.

Therefore, weight, waist circumference and blood pressure were measured and 2 ml of blood

was drawn using sterile technique for fasting blood glucose measurement; used tea bags were

counted and recorded. At the last visit (visit 5, week 12), patients underwent the last

assessment with similar procedures as visit 1.

Assessment of participant's compliance with the intervention was done by counting the used

tea bags during each visit. Participants were considered non-compliance when they reported

that they were unable to comply with the tea drinking routine or the tea bags counted was

noted less than 80% in amount for that visit without valid reasons. Patients who were not

compliant or have discontinued the consumption, defaulted follow up, and have had changes

in their diabetic medications regime list, were excluded from the study.

Subjects were allowed to withdraw from the study at any time if they were unable to tolerate

the side effects. These patients were referred back to the outpatient clinic and continue with

the standard care.

Outcomes

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The primary outcome was to observe the influence of GCT on HbA1c levels. Reduction in

fasting blood glucose and insulin levels, body weight, waist circumference, lipid profile and

blood pressure were the secondary outcomes.

Statistical analysis

Analysis was done using SPSS version 20.0. In the descriptive data, numerical values were

expressed as mean (SD) and categorical values were expressed as n (%). Statistical analyses

were done by using independent t-test to compare changes from baseline and at 12 weeks.

Repeated measure ANOVA analysis was used to show significant changes of relevant

parameters over time.

The study was approved by the Research Ethics Committee of the School of Medical

Sciences, Universiti Sains Malaysia in 2013 (USMKK/PPP/JEPeM [258.3(8)]). The patients’

personal identification and clinical data were kept confidential and reported as collective

information and not on personal basis.

Results

Eighty two T2DM patients were screened for this study. Seven patients were excluded as

they were not eligible and did not meet the criteria such as having a HbA1c level of more

than 10% and other diabetes complications such as renal impairment. Another eight patients

were eligible but refused to join the study due to logistic problem, and they were not

committed to come for frequent visit. Hence, 67 subjects were recruited but only 64 subjects

completed the study. Thus, the respond rate of this study was 89.3%. Reasons for stopping in

three subjects were due to the side effects. The first subject experienced constipation and

bloatedness after 1 week of the trial but she persisted until week 3, during which she decided

to withdraw from the study. The second patient had bloatedness after 3 days of taking the tea

and decided to stop after week 1. The third patient experienced colicky stomachache and

bloatedness after two days into the study and decided to withdraw after 1 week.

10

The mean (SD) age of the subjects is 50.6 (7.3). Majority of the subjects are female, married,

Malays, nonsmoker and employed (Table 1).

Table 1: Socio-demographic characteristic of the subjects

Variable n(%) mean (SD)

Age (year) 50.6 (7.3)

Race

Malay

Chinese

63 (98.4)

1.6 (1.6)

Gender

Male

Female

23(35.9)

41(64.1)

Marital status

Single

Married

Divorced

Widowed

3(4.7)

56(87.5)

4(6.3)

1(1.5)

Education

Primary school

Secondary school

University

5 (7.8)

37 (57.8)

22 (34.4)

Smoking

Smoker

Non-smoker

Ex-smoker

3 (4.7)

57 (89.1)

4 (6.2)

Working

Government

Private

Self-employed

Pensioner

Housewife

46(71.9)

1(1.6)

5(7.8)

8(12.4)

4 (6.3)

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The mean BMI is 29.6 kg/m2 with waist circumference of 94.7 cm, HbA1c was 8.6% and

blood pressure is 130/80 mmHg (Table 2).

Table 2: Physical examination and metabolic component of the subjects

Variable mean (SD)

Height (cm) 158.2 (9.0)

Weight (kg) 73.2 (16.4)

Waist circumference (cm) 94.7 (14.7)

BMI (kg/m2) 29.6 (5.6)

Systolic blood pressure (mmHg) 130.0 (13.2)

Diastolic blood pressure (mmHg) 80.23 (12.6)

HbA1c (%) 8.6 (0.9)

Serum insulin (pmol/L) 84.6 (57.3)

Fasting blood sugar (mmol/L) 9.3 (2.9)

HDL(mmol/L) 1.16 (0.25)

LDL (mmol/L) 2.9 (1.0)

TG (mmol/L) 1.9 (1.1)

Chol (mmol/L) 5.0 (1.0)

Abbreviation: SD standard deviation, BMI body mass index, LDL low density lipoprotein, TG triglyceride,

CHOL cholesterol, HDL high density lipoprotein, WC waist circumference.

Table 3 shows the results of physical examination and metabolic components pre and post

intervention (week-12). A significant reduction in the mean of HbA1c (p<0.001) is observed

by week-12 [mean difference 1.1% (95%CI 0.84-1.37)].

Table 4 shows the comparison of mean FBS, body weight, systolic and diastolic blood

pressure base on time visits. The mean of fasting blood sugar (FBS) level is significantly

different between each visit. A one way repeated measure ANOVA with a Greenhouse-

Geisser correction determined that mean FBS differed statistically significantly between time

points [F (2.836, 178.63)=5.24, p= 0.002]

12

Pair wise comparison using paired t-test with Bonferroni correction in FBS shows statistical

significant difference in FBS means at week-4 (p=0.001) and 5 (p=0.007) compared to

baseline (Table 5).

Overall compliance with the study’s medication is 96.4%. There are no changes in the

toxicity profile parameters such as full blood count, renal function tests and liver function

tests at pre- and post-interventions (Table 6).

Table 3: Physical examination and metabolic components at pre- and post-interventions

Table 4 : Comparison of means for FBS, body weight, systolic and diastolic blood pressure

based on time visits

Variables

Visit1

Mean(SD)

95%CI

Visit2

Mean(SD)

95%CI

Visit3

Mean(SD)

95%CI

Visit4

Mean(SD)

95%CI

Visit5

Mean(SD)

95%CI 5

F stat

p-value*

FBS

(mmo/L)

9.37(0.36)

8.65-10.1)

9.08(0.36)

(8.31-9.75)

8.76(0.35)

(8.01-9.43)

8.05(0.29)

(7.45-8.58)

8.19(0.30)

(7.56-8.77)

5.24 0.002

Body Weight

(Kg)

73.3(2.06)

(69.1-77.4)

71.7(2.33)

(67.0-76.3)

72.2(2.27)

(67.6-76.7)

72.5(2.03)

(68.5-76.6)

73.2(1.99)

(69.2-77.2)

0.91 0.457

Variable

Pre

mean(SD)

Post

mean(SD)

Mean difference

95%CI

p-value*

WC (cm) 94.7(14.72) 93.8(12.20) 1.90(-1.40, 3.21) 0.435

SBP (mmHg) 130.1(13.24) 126.4 (12.42) 2.70(-0.82, 6.19) 0.137

DB (mmHg) 80.0(12.65) 77.9(9.70) 2.30(-1.03, 5.59) 0.176

HbA1c (%) 8.7(0.90) 7.6(1.12) 1.10(0.84, 1.37) <0.001

LDL (mmol/L) 3.0(0.90) 3.1(0.92) -0.10(-0.37, 0.16) 0.450

TG (mmol/L) 1.9(1.15) 1.9(0.90) 0.03(-0.21, 0.29) 0.761

Chol (mmol/L) 5.1(1.06) 4.9(1.19) 0.13(-0.17, 0.44) 0.381

HDL (mmol/L) 1.2(0.25) 4.0(0.25) -2.84(-8.42, 2.73) 0.315

Insulin (pmol/L) 83.0(60.12) 96.6(54.67) -13.53(27.52,0.44) 0.058

*independent t-test. p value < 0.05 set as significant at 95%CI

Abbreviation: SD standard deviation, BMI body mass index, LDL low density lipoprotein, TG

triglyceride, CHOL cholesterol, HDL high density lipoprotein, WC waist circumference, SBP systolic

blood pressure, DB diastolic blood pressure.

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Systolic BP

(mmHg)

130(0.37)

(126-133)

129(0.36)

(126-132)

128(0.35)

(125-131)

127(0.28)

(123-130)

127(0.29) 1.69 0.161

Diastolic BP

(mmHg)

80(1.58)

77-88)

78(1.08)

(76-80)

78(1.08)

(76-80)

77(1.04)

(75-80)

77(1.21)

(75-80)

1.28 0.281

*Repeated measure ANOVA,

p value < 0.05 set as significant at 95%CI

SD standard deviation, FBS fasting blood sugar, BP blood pressure

Table 5: Mean Difference of Fasting Blood Sugar of the subjects during the different

visits

FBS

Visit

Mean

St.Error

P value*

95% confidence interval

Lower bound Upper bound

1 2 0.356 0.367 1.000 -0.713 1.42

3 0.663 0.364 0.700 -0.396 1.72

4 1.375 0.337 0.001 0.394 2.35

5 1.217 0.342 0.007 0.222 2.21

*Pair wise comparison using pair T test with Bonferroni correction in FBS showed statistical significant

difference in mean FBS between follow ups. From base line (V1) to visit 4 and also from baseline (V1) to visit

5.

Table 6: Toxicology profile of the subjects pre- and post- interventions

Variable Pre

Mean (SD)

Post

Mean (SD)

p-value*

Full Blood count

Hb(g/dL)

Hct (%)

Platlet (x109)

13.7 (1.60)

41.2 (4.4)

278 (87.0)

13.7 (1.50)

41.4 (4.60)

275 (89.2)

0.205

0.638

0.304

Renal function test

Urea(mmo/L)

Serum creatinine(mmol/L)

5.7 (7.4)

96.72 (51.7)

4.7 (1.34)

84.54 (18.6)

0.582

0.055

Liver function test

AST(UI/L)

ALP(UI/L)

ALT(UI/L)

36.7 (16.0)

85.7 (28.2)

47.9 (30.1)

37.0 (18.2)

82.2 (25.9)

48.1 (36.3)

0.898

0.294

0.929

*Independent t-test, p value < 0.05 set as significant at 95%CI

Abbrevation: Hb hemoglobin, HCT hematocrit, AST aspartate aminotransferase, ALP alkaline

phosphatase ALT alanine transaminase.

14

DISCUSSION

To the best of our knowledge, this is the first report on the effect of GS and CS supplements

combination on the metabolic status of patients with uncontrolled type 2 T2DM who are on

oral hypoglycaemic agents (OHA).

This study shows that the HbA1 and FBS levels improved after consumption of the GCT

drinks regularly for 12 weeks. The HbA1c level was significantly reduced by 1.1%. This is

supported by a study done among T2DM patients whereby GS leaves were given as a

supplement for 20 months to the conventional OHA in which a significant reduction in blood

glucose and HbA1c levels were observed (Baskaran et al., 1990). A cross-over randomized

controlled trial on volunteered patients with abnormal sugar level also showed to lower the

HbA1c level when the patients were given a daily supplement of green-tea-extract powder

from the CS leaves (Fukino et al., 2008). A recent meta-analysis on the effect of green tea on

glucose control and insulin sensitivity looking at 17 randomize control trials concluded that

fasting blood glucose and HbA1c levels were significantly lowered by consuming green tea

(Liu et al., 2013) .

At week-8 and week-12, the FBS level was reduced by 1.37 and 1.22 mmol/L, respectively.

The reduction of fasting blood sugar can be seen significantly after 2 months of tea

consumption. A cross sectional study done in Japan among 35 males found that the higher the

concentration of green tea the higher the ability to reduce the blood glucose level (Maruyama

et al., 2009). Similarly, there was a study done on non-obese elderly which noted that tea

could reduce the level of fasting blood glucose level (Polychronopoulos et al., 2008). An in

vitro study on epididymal fat cell showed that CS increased the insulin activity by more than

15-fold especially during post prandial time (Osada et al., 2001) which led to the reduction of

glucose in the blood. In animal studies, CS also has shown the ability to reduce the blood

sugar and body weight among diabetic mice (Tsuneki et al., 2004).

In our present study, there are some improvements in the serum insulin level; however it is

not statistically significant. This is in contrast to a study done by Baskaran et al. (1990)

which showed that there was an increase in insulin level. In his study, the supply of the GS

was given for a longer duration of 18-20 months. Similarly, study by Shanmigasundraram et

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al. (1990) claimed that there was a possibility of beta cell regeneration. In that study, GS

supplement was given to the study subjects for 12 months. As compared to the present study,

the supplement was given only for 3 months. Therefore, better results in the insulin level of

participants probably could be observed when an extended duration is to be applied.

In the present study, the effects of the GCT on the secondary outcome such as body weight,

blood pressure and cholesterol level were not significant. This is supported by one meta-

analysis which also showed that green tea had no significant effect for weight loss and weight

maintenance (Jurgens et al., 2012). There is no study reported that GS as a single herb can

reduce the weight but it has been reported that GS when it was combined with other herbs

and vitamins caused significant body weight and fat loss (Woodgate and Conquer, 2003).

As for blood pressure and lipid profile there were no significant changes noted in this study.

This finding is similar to the study by Fukino et al. (2008), where their intervention found no

significant changes in BMI, systolic blood pressure and serum lipid; however, in their study

the green tea-extract powder supplement was given for a 2-month durations to 60 volunteers

with abnormal glucose level who were not diabetic patients.

Majority of the patients in the present study could tolerate the tea, with only a small number

of patients who had to stop the intervention due to the appearance of unwanted side effects.

There were two reasons for stopping the study: constipation and bloatedness. Tea, for certain

people, can lead to increase intestinal transit time which leads to constipation. (Højgaard et

al., 1981). Similarly, Chow et al. (2003) also reported bloatedness and stomach upset that

were caused by the tea. However, in this trial the participants did not report any of these

symptoms except for bloatedness.

This study had some limitations owing to the study design and sampling method. There is no

way to prove the effectiveness of the product without a control group. Therefore, we can only

conclude that there is an influence of the product on HBA1c and fasting glucose levels. In

terms of the sampling method, although the study finding is valid and reliable, we cannot

infer the findings to other T2DM patients on OHA since no randomization was carried out.

16

However, this study provides a significant justification on the need for proper randomized

controlled trial in order to prove the effectiveness of the product.

Conclusion

GlucosCare Herbal Tea has been shown in this study to have effect on reducing the HbA1c

and fasting blood glucose levels in patients with uncontrolled Type 2 Diabetes Mellitus on

oral hypoglycaemic agents after consuming the tea for 12 weeks.

Acknowledgement

This study was supported by the Educational Grant from National Diabetes Institutes

(NADI). The authors would like to thank research assistant, medical officers and nurses from

KRK for making this study a success.

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