Effect of Propolis or Metformin Administration on Glycemic Control in Patients With Type 2 Diabetes Mellitus Without Pharmacological Treatment
Phase: PHASE2
Conditions: Diabetes Mellitus, Type 2
Sponsor: University of Guadalajara

 
 
 
 
 
“Effect of Propolis or Metformin Administration 
on Glycemic Control in Patients With Type 2 
Diabetes Mellitus” 
 
NCT03416127 
 
April 6, 2017 
 

Effect of Propolis or Metformin Administration on Glycemic Control in 
Patients With Type 2 Diabetes Mellitus 
 
INTRODUCTION 
Type 2 Diabetes Mellitus (DM2) is a health problem that has reached alarming levels, as 
currently, about half a billion people suffer from it around the world. For 2019, a total of 463 
million was estimated and an increase of 51% is expected by 2040.1 It is a disease 
characterized by dysfunction of beta cells, hepatic glucose metabolism and peripheral insulin 
resistance, a state in which tissues sensitive to it show a decreased response to normal insulin 
levels.2  
The first-line treatment in newly diagnosed patients is metformin, mainly due to its efficacy 
in reducing glycemic control, safety profile, and weight neutrality.3,4 However, this depends 
on factors such as treatment compliance, access to medicines, counseling, regular monitoring 
of blood sugar levels, access to health care services, and quality of management. To date, a 
significant number of people around the world use complementary and alternative medicine 
(CAM) to treat chronic diseases, with reports of 64%. Of these, 35.5% use CAM for DM2.5 
Propolis, is a natural product produced by the bee Apis mellifera by adding salivary secretions 
(β-amylase) and wax to the balsamic resinous material, which they collect from shoots, 
exudates of trees and other parts of the plants as lipophilic materials in the leaves, mucilages, 
gums, resins, latex, etc. Etymologically the term propolis, comes from the Greek and means 
in “defense of the city (or beehive)”.6–9 It has been known and used since ancient times by 
offering options such as antimicrobial, anti-inflammatory, antioxidant, antitumor, antiulcer, 
anesthetic, hepatoprotective and healing therapy.6,10,11 It is composed of flavonoids, terpenes, 
phenolic acids, as well as proteins, sugars, vitamins and abundant minerals.10,11 
Recent studies have shown the efficacy of propolis on the reduction of fasting glucose and 
glycated hemoglobin,9,12,13 insulin resistance13,14 and postprandial glucose.14 However, there 
is a controversy between some results, as Fukuda et al. indicated that there was no significant 
difference in the parameters of glycemic control and insulin resistance.15 Likewise, Zakerkish 
et al. found no relevant reduction in fasting glucose after propolis supplementation.14 

Therefore, there is a need for further studies, as there is no evidence from studies evaluating 
the effect of propolis on glycemic control in newly diagnosed patients without drug 
treatment. In addition to this, it has not been compared to the gold standard, metformin. Our 
hypothesis is that the administration of propolis or metformin modifies glycemic control in 
newly diagnosed patients without pharmacological treatment. The objective of this study is 
to evaluate the effect of propolis or metformin administration on glycemic control in recently 
diagnosed patients without pharmacological treatment. 
 
MATERIAL AND METHODS 
Selection criteria 
Patients with a diagnosis of DM2 less than 5 years old and without pharmacological treatment 
for at least 3 months before entering the study, 30 to 60 years of age, mild to moderate 
physical activity, stable body weight for at least 3 months before the study, body mass index 
(BMI) of 25.0 to 34.9 kg/m2, fasting serum glucose <13.88 mmol/L and postload serum 
glucose >11.10 mmol/L, will be criteria for entering the study. For the selection of individuals 
diabetes detection campaigns will be carried out in the metropolitan area of the City of 
Guadalajara. Women in the reproductive stage at risk of pregnancy, subjects who consumed 
drugs or supplements that modify the behavior of DM2, personal history of cardiovascular, 
kidney, pancreatic or thyroid disease and/or uncontrolled systemic arterial hypertension, 
known allergies to bee’s sting or its derivative products, intolerance to metformin, total 
cholesterol (TC) ≥6.20 mmol/L, triglycerides (TG) ≥4.48 mmol/L will be excluded. 
Individuals with lack of tolerability to propolis, metformin and/or placebo, with adherence 
to treatment <80%, in the presence of a serious adverse event and/or who withdrew informed 
consent will be eliminated. 
 
Study design 
A randomized, double-blind, placebo-controlled clinical trial of three pharmacological 
groups will be carried out, with the participation of 34 patients with a recent diagnosis of 
DM2 according to the criteria of the American Diabetes Association.16 The propolis capsules 

will be obtained from NOW® of Chicago, Illinois (USA), containing 300 mg of propolis 
powder. Calcined magnesia will be used for the placebo. The allocation will be done by 
simple randomization using a list of numbers. All patients will receive for 12 weeks one 
capsule before the first bite of breakfast and another before the first bite of dinner. 12 of them 
took propolis (300 mg twice a day), another 12 received metformin (850 mg twice a day) and 
12 more, placebo in the same pharmacological presentation. Each participant will receive 
medical nutritional therapy and will be instructed to continue with their normal physical 
activity. 
 
Clinical and laboratory measurements 
The medical history of each patient will be taken and anthropometric indices will be 
measured that included: height, weight, BMI, waist circumference (WC) and percentage of 
fat mass. In addition to blood pressure. Five visits will be completed during the study and a 
2-h oral glucose tolerance test (OGTT) will be performed at the beginning and end of the 
intervention to calculate the areas under the curve (AUC) of glucose and insulin, total insulin 
secretion (insulinogenic index), first phase of insulin secretion (Stumvoll index) and insulin 
sensitivity (Matsuda index). For this, the individuals will take a solution with 75 g of 
anhydrous glucose dissolved in 300 ml of water in 5 minutes. After that, blood samples will 
be taken through a heparinized catheter before and at 30-min intervals (30, 60, 90 and 120 
minutes) for 2 hours. At each visit, the presence of adverse events will be verified through 
the diary and compliance through the capsule count. 
Laboratory tests will be performed at 8:00 a.m. after an overnight fast from 10 to 12 h. Body 
weight will be evaluated by bioimpedance with a digital scale (Tanita®), with the participant 
in a standing position and wearing light clothing, without footwear and with the bladder 
evacuated before the measurement. For height, subjects will be asked to remove their shoes 
and stand with their feet together; measurements will be rounded to the nearest centimeter. 
WC will be taken at the midpoint between the highest point of the iliac crest and the lowest 
rib on the midaxillary line to the nearest centimeter. Percentage of fat mass will be evaluated 
through bioimpedance. BMI will be calculated as weight (kg) divided by height (m2). A 
digital sphygmomanometer (Omron Hem-907 XL®) will be used to determine blood 

pressure, and the mean value of three measurements will be recorded after a 5-min rest 
period. 
Venous blood samples will be obtained and kept at room temperature for 30 min. The 
samples will be centrifuged and the serum will be placed in three aliquots; one will be used 
immediately for the measurement of fasting glucose, glycated hemoglobin A1c (A1C), TC, 
TG, high-density lipoprotein cholesterol (HDL-c), uric acid and creatinine, and the rest will 
be frozen at -20 °C for the determination of insulin. All biochemical measurements will be 
calculated with enzymatic colorimetric methods on an automatic analyzer (Erba XL-100®) 
with BioSystems S.A. reagents. Insulin concentrations will be measured with the enzyme-
linked immunosorbent assay (ELISA) technique using the kit (DRG, Inc). 
To calculate low-density cholesterol, the Friedewald formula will be used: LDL-c (mmol/L)= 
TC (mmol/L) - HDL-c (mmol/L) - [TG (mmol/L) / 2.2], while for very low density 
cholesterol (VLDL) the ratio of TG (mmol/L) / 2.2 will be used. With a liquid 
chromatography the percentage of A1C will be calculated. The AUC of glucose and insulin 
will be calculated with the polygonal formula. Total insulin secretion will be assessed with 
the insulin index: (∆AUC of insulin) / (∆AUC of glucose). With the Matsuda 10000 / √ 
([(Glucose 0^ '∙ Insulin 0 ^') (Average of the PTOG ∙ Average of the insulin in the PTOG)]) 
index the insulin sensitivity will be estimated, while with the index from Stumvoll 1283 + 
1.829 × insulin 30' - 138.7 x glucose 30’ + 3.772 × insulin 0', the first phase of insulin 
secretion. 
 
Sample size 
For this study, the sample size it’s calculated using a formula for mean difference17 with a 
statistical confidence of 95%, a statistical power of 80%, a standard deviation (SD) and an 
expected difference for fasting glucose, A1C and 2-h glucose of 0.6 mmol/L12 and 1.0 
mmol/L9,  0.5% and 0.8%12, 2.3 mmol/L18 and 3.9 mmol/L19, respectively. While for 
metformin it’s of 2.4 mmol/L20 and 3.0 mmol/L21, 1.0% and 1.5%22, 3.5 mmol/L23 and 5.5 
mmol/L24, respectively. A total of 12 patients is obtained for each group, including 20% of 
the expected loss. 

Security measures 
All patients will be informed about the possible adverse effects of propolis and metformin; 
they will have the emergency telephone numbers of the responsible and associated 
investigators. 
 
STATISTIC ANALYSIS 
The study will be designed to demonstrate the effect of propolis and metformin relative to 
placebo in terms of the outcome variables of effectiveness. Assuming there are no differences 
in propolis and metformin versus placebo regarding effectiveness in reducing glycemic 
control, it's calculated that approximately 36 randomized patients will provide ~80% power 
to demonstrate superiority. 
All statistical analyzes will be performed by intention to treat, which will be included 
randomized patients who receive at least 1 dose of study treatments and for whom there has 
a baseline value on measurements. First, with the Kruskal-Wallis test, it will be tested 
whether the baseline data group of primary and secondary variables come from the same 
population, that is, whether the 3 groups are comparable as no statistically significant 
differences are found. 
Then, using the Kruskal-Wallis test, the final data will be evaluated and with those that will 
be significant a post-hoc test (Mann Whitney U) will be performed, comparing propolis 
versus metformin, propolis versus placebo, and metformin versus placebo. Differences 
between baseline and final measurements for primary and secondary variables will be 
calculated with the Wilcoxon test. Statistical comparisons will be made using a comparative 
type 1 error of 5% (two-tailed). 
The safety profile analysis will include patients who receive at least 1 dose of study 
medication; safety data will be summarized using descriptive statistics. 
 
FINANCING 
The financing will be by own resources of the University of Guadalajara. 

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