Oleanolic acid (OA), is a natural component of many plant food and medicinal herbs, which has shown to exert in experimental models hypoglycemic and hypolipidemic effects, and also a cytoprotective action against oxidative and chemotoxic stress underlying Type II Diabetes Mellitus (T2DM).Today it is known that OA shares mechanisms of action with metformin and other drugs of choice for the treatment of diabetes. Therefore, the OLTRAD (OLeanolic acid TReAtment for type 2 Diabetes) Study, a prospective, parallel group, randomized, double-blind, controlled trial with 100 participants, has been designed to demonstrate that the regular intake of an OA-enriched functional olive oil is effective as an adjuvant to metformin antidiabetic drug therapy. The hypothesis is that the inclusion of this functional olive oil in the diet will enhance the effects of the pharmacological treatment in diabetic patients, and may even reduce the need for prescription of such medications.
TRIAL DESIGN The OLTRAD Study is a prospective, parallel group, randomized, double-blind, controlled trial designed to demonstrate that the regular intake of an OA-enriched functional olive oil is effective as an adjunct to metformin therapy (as monotherapy or in combination with other antidiabetic drugs) in the metabolic control of T2DM patients. The effect of the OA-enriched olive oil will be compared with that of the control oil, which consists of the same commercial olive oil not fortified in the triterpene. A total of 100 volunteers of both sex will be selected from among the T2DM patients treated at the Endocrinology and Nutrition Service of the 'Virgen del Rocío' University Hospital (Seville, SPAIN). SAMPLE SIZE CALCULATION Serum glycosylated hemoglobin (HbA1c) is adopted as the main quantitative variable for the analysis of glycemic control. The null hypothesis stated in the trial design is that the OA-based dietary intervention will reduce the baseline serum HbA1c levels of patients by at least 7%, compared to the control group. To test this one-sided hypothesis test with a 95% confidence level (α risk = 0.05) and 95% power (β risk = 0.05), a sample size of 44 volunteers per group is required. However, due to the characteristics of the study (a long-term lifestyle intervention), participant losses of up to 15% can be assumed, resulting in an adjusted sample size of 50 individuals per group. RANDOMIZATION Once recruited, the 100 T2DM patients will be randomly assigned to one of the two study groups. Fifty individuals will be assigned to the intervention group, which will ingest the OA-enriched functional olive oil, whereas the other 50 volunteers will be assigned to the control group, which will receive the same non-enriched olive oil. At the time of admission, the study nursing staff will request by telephone the clinical coordinator of the trial (Principal Investigator 2 of the Project) the assignment of participants to the study groups (centralized randomization). Allocation to these groups will be made using computer generated tables of random numbers. Four randomization strata will be constructed by sex and age (cuttof 50 years). INTERVENTION Participants will be instructed to ingest 55 mL/day of the assigned oil, preferably raw and freely distributed among the three main meals. Both the OA-enriched olive oil and the control oil will be delivered labeled with alphanumeric codes, the correspondence of which will only be known by the Principal Investigator 1 of the project. This ensures blinding of the clinical researchers and participants with respect to the type of olive oil assigned. FOLLOW-UP Participants in the clinical trial will be followed up for 12 months from enrollment, according to a plan of quarterly visits. At the time of recruitment and every three months thereafter, participants will be measured for anthropometric, blood pressure, and heart rate measurements. They will also be asked about gastrointestinal disorders or other types of complaints, and will complete a questionnaire on lifestyle (diet, physical activity, alcohol and tobacco use), medical conditions, and medication use. Also at the beginning of participation in the study and every three months thereafter, fasting blood samples will be drawn from the cubital vein, which will be collected in sterile plastic tubes with a vacuum system. Similarly, participants will provide aliquots of their first morning urine in sterile plastic tubes. The analytical determinations in blood and urine will be carried out in the Clinical Biochemistry and Analysis Laboratory of the 'Virgen del Rocío' University Hospital in Seville (HUVR). In addition, aliquots of plasma will be sent to the 'Instituto de la Grasa' (IG-CSIC) for complementary biochemical determinations. Laboratory technicians from both institutions will receive the samples identified with alphanumeric ID codes and, therefore, will be blinded to the intervention groups. In these quarterly visits, volunteers will participate in sessions of the nutritional education program and will receive 6 L of the assigned oil for free. Adherence to the dietary intervention will be assessed quarterly through the Haynes-Sackett's self-reported compliance test and the return of empty bottles presumably consumed. The primary outcome of the trial is the improvement in glycemic control, assessed by the evolution of HbA1c. As secondary results, we will obtain data on anthropometric and clinical variables, as well as on biochemical parameters of blood and urine. ANAMNESIS AND CLINICAL EXAMINATION OF PARTICIPANTS The medical researchers of the project have access to the electronic medical records of the participants in the platform DIRAYA of the Andalusian Health Service, and will carry out the anamnesis and physical examination of the participants, which will include vital data and general medical and surgical history, as well as the pharmacological treatments followed. Information will also be obtained on lifestyle, perception of their own body image, diet, and the type and intensity of physical activity. In addition, a general clinical examination will be carried out including general appearance and inspection of hands and arms, feet and legs, skin, face, eyes, mouth, neck, abdomen, edema, lymph nodes, and vital signs (temperature, pulse, respiratory rate and blood pressure). ANTHROPOMETRIC STUDY AND BODY COMPOSITION The anthropometric study will include the determination of total body weight, height, body mass index (BMI), as well as waist and hip circumferences. The study and evaluation of these variables will be carried out according to the guidelines of the International Society for the Advancement of Kinanthropometry (ISAK). The study of body composition will be carried out by electrical bioimpedance. Fat mass, lean mass, muscle mass, total water, bone mass, basal metabolism, and visceral fat will be quantified with this technique, using validated prediction equations adjusted for age and sex. ASSESSMENT OF FOOD INTAKE AND NUTRITIONAL TRAINING A nutritional education program will be implemented to assess the food intake of the participants and reinforce compliance with the dietary recommendations given. To measure food intake, we will use the food intake registration form designed by the University of Navarra (Spain) and used successfully in other trials, such as the PREvención con DIeta MEDiterránea (PREDIMED) study. This form is a validated tool that quantifies food intake in terms of food portions or food groups for adults living in Spain. On the other hand, all the participants will join workshops where they will receive specific dietary recommendations for patients with T2DM, and they will be instructed on a healthy diet, the best food options and adequate portions, limiting highly processed foods, cakes, sugar, fatty foods as well as sugary and alcoholic beverages. Additionally, patients will gain information on recipes, seasonal shopping lists, and the use of olive oil for cooking and dressing. The eating habits of the participants will be analyzed quarterly by means of a 24-hour recall questionnaire. The 'NUTRIUM' software (https://nutrium.com/; Braga; Portugal) for the nutritional evaluation of the diets will be used. BLOOD BIOCHEMISTRY IN HUVR In ulnar blood samples, determinations related to circulating lipids \[total triglycerides, total cholesterol, LDL, HDL, total apolipoprotein B and lipoprotein A\]; glucose homeostasis \[glycemia, insulinemia, C-peptide, HOMA-IR index, HbA1c\]; oxidative stress and inflammation \[uric acid, bilirubin, malondialdehyde, ultrasensitive C-reactive protein, thyroid-stimulating hormone (TSH)\], as well as those associated with liver and kidney damage \[lactate dehydrogenase (LDH), liver transaminases (ALT, AST, GGT ) and creatinine\] will be performed. Plasma level of vitamin B12 will be also assessed. In addition, the possible appearance of liver fibrosis will be evaluated through the Hepamet Fibrosis Score, a non-invasive method that calculates a score taking into account factors such as age, sex, presence of diabetes, glucose levels, insulin, albumin, platelets, and AST. This tool, designed by the Seville Institute of Biomedicine (IBiS), is indicated to assess suspected fibrosis in patients with obesity, diabetes, metabolic syndrome, hepatic steatosis, and/or abnormal liver function markers. The method offers diagnostic reliability and a cost/benefit ratio that is superior to other methods, such as the FIB-4 and the NAFLD Fibrosis Score. CONTINUOUS BLOOD GLUCOSE MONITORING Plasma glucose will be continuously monitored using the 'FreeStyle Libre' subcutaneous system (ABBOTT Diagnostics; Chicago, IL.; USA). The sensors will be attached to the participants at two times throughout the trial: at baseline and after 12 months of follow-up, and will collect data for 48 hours. With this system, different glycemic parameters will be determined, such as the area under the curve (AUC), the mean amplitude of the glycemic excursion (MAGE), the mean glycemia, as well as the standard deviation (SD) and the coefficient of variation (CV). PLASMA BIOCHEMISTRY IN IG-CSIC The investigators of the IG-CSIC will perform a number of complementary determinations in plasma samples, such as the plasmatic concentrations of OA, the glutathione (GSH and GSSG) levels, the fatty acid composition, serum adipokines (ceruloplasmin, adiponectin, leptin, resistin, and ghrelin). Serum Antioxidant enzymes (superoxide dismutase, catalase) and proinflammatory cytokines (TNF-α, IL-1β, IL-6) will also be determined. On the other hand, the VLDL fraction of plasma lipoproteins will be isolated by ultracentrifugation (230,000 × g for 18 h at 4 °C). In these particles, the total content of fatty acids, triglycerides, diglycerides, phospholipids and total Apolipoprotein B will be measured. URINE ANALYSIS The first morning urine samples will be analyzed for the usual physical, chemical, and microscopic determinations (pH, density, glycosuria, ketones, nitrites, urobilinogen, bilirubin, sediment, leukocytes, microalbuminuria/g creatinine). The determination of these parameters will also be carried out in the facilities of the Clinical Biochemistry and Analysis Laboratory of the 'Virgen del Rocío' University Hospitals in Seville. STATISTICAL ANALYSIS The trial will be conducted according to the intention-to-treat (ITT) principle. Qualitative variables will be expressed by their absolute and relative frequencies, whereas the quantitative ones with normal distribution will be expressed by the mean and standard deviation and those with non-normal distribution by the median and interquartile range (IQR). Comparisons between study groups for qualitative variables will be performed with the Chi-square and McNemar's tests, whereas comparisons for quantitative variables will be executed with the Student's t-test and ANOVA. The homogeneity of the populations included in the allocation groups will be evaluated using theMann-Whitney-Wilcoxon U-test. All P-values will be two-tailed at α = 0.05. Statistical analysis will be performed with SPSS 27 (IBM SPSS Statistics, NY, USA) software
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
QUADRUPLE
Enrollment
100
Dietary intervention in diabetic patients. Oral intake of 55 mL/day of a functional olive oil enriched in Oleanolic acid (equivalent dose 30 mg/day OA) Oleanolic acid (CAS no. 598-02-1; PubChem CID 10494).
Dietary intervention in diabetic patients. Oral intake of 55 mL/day of a commercial olive oil (blend of virgin and refined olive oils) chosen by its very low content of bioactive minor components.
Virgen del Rocío University Hospital
Seville, Andalicía, Spain
HbA1c
The primary outcome of the trial is the evaluation of the glycemic control, assessed through the evolution of the plasma glycosylated hemoglobin (HbA1c) level, expressed in %
Time frame: 1 year
Body weight
Body weight (expressed in kilograms, kg) wil be determined using a TANITA® model BC-418MA body composition analyzer.
Time frame: 1 year
Body height
The body height (expressed in meters, m) will be determined by using an approved column stadiometer
Time frame: 1 year
Body mass index (BMI)
body weight and height will be combined to report BMI in kg/m\^2, according to the equation BMI = body mass/(height)\^2
Time frame: 1 year
Waist circumference
Waist circumference (expressed in centimeters, cm) will be measured with a measuring tape
Time frame: 1 year
Hip circumference
Hip circumference (expressed in centimeters, cm) will be measured with a measuring tape
Time frame: 1 year
Body composition - fat mass
Fat mass (expressed in kilograms, kg) will be measured using a TANITA® (model BC-418MA) body composition analyzer. Quantification will be made using validated prediction equations adjusted for age and sex.
Time frame: 1 year
Body composition - visceral fat mass
Visceral fat mass (expressed in kilograms, kg) will be measured using a TANITA® (model BC-418MA) body composition analyzer. Quantification will be made using validated prediction equations adjusted for age and sex.
Time frame: 1 year
Body composition - lean mass
Lean mass (expressed in kilograms, kg) will be measured using a TANITA® (model BC-418MA) body composition analyzer. Quantification will be made using validated prediction equations adjusted for age and sex.
Time frame: 1 year
Body composition - muscle mass
Muscle mass (expressed in kilograms, kg) will be measured using a TANITA® (model BC-418MA) body composition analyzer. Quantification will be made using validated prediction equations adjusted for age and sex.
Time frame: 1 year
Body composition - bone mass
Bone mass (expressed in kilograms, kg) will be measured using a TANITA® (model BC-418MA) body composition analyzer. Quantification will be made using validated prediction equations adjusted for age and sex.
Time frame: 1 year
Body composition - total water composition
Total water composition (expressed in litre, L) will be measured using a TANITA® (model BC-418MA) body composition analyzer. Quantification will be made using validated prediction equations adjusted for age and sex.
Time frame: 1 year
Basal metabolism
Basal metabolism (expressed in kilojoule, kJ) will be measured using a TANITA® (model BC-418MA) body composition analyzer. Quantification will be made using validated prediction equations adjusted for age and sex.
Time frame: 1 year
Diastolic blood pressure (DBP)
DBP (expressed in milimeters of mercury) using a calibrated automatic sphygmomanometer
Time frame: 1 year
Systolic blood pressure (SBP)
SBP (expressed in milimeters of mercury) using a calibrated automatic sphygmomanometer
Time frame: 1 year
Pulse
heart rate measured with a calibrated automatic sphygmomanometer
Time frame: 1 year
Serum glucose
Determined by enzymatic method and expressed in miligrams/decilitre (mg/dL)
Time frame: 1 year
Serum insulin
determined by commercial ELISA kit and expressed in international microunits per millilitre (µIU/mL)
Time frame: 1 year
HOMA-IR index
serum glucose (expressed in millimole/litre) and serum insulin (expressed in µIU/mL) are combined to report the homeostatic model assessment for insulin resistance (HOMA-IR), according to the equation HOMA-IR = (glucose x insulin)/22.5 HOMA-IR= \[serum insulin (μU/ml) × blood glucose (mmol/l)\]/22.5}.
Time frame: 1 year
Serum C-peptide
measured by commercial ELISA kit and expressed as nanogram/millilitre (ng/mL)
Time frame: 1 year
Plasma triglycerides (TG)
plasma concentrations of total triglycerides is determined by an automated colorimetric enzymatic method (GPO-PAP, Roche Diagnostics, Mannheim, Germany) and expressed as milligrams/decilitre (mg/dL)
Time frame: 1 year
Plasma total cholesterol (CT)
plasma concentrations of total cholesterol is determined by an automated colorimetric enzymatic method (CHOD-PAP, Roche Diagnostics, Mannheim, Germany) and expressed as milligrams/decilitre (mg/dL)
Time frame: 1 year
Plasma high density lipoproteins (HDL)
plasma concentrations of HDL is determined by an automated direct enzymatic method (HDL-C-plus 2nd generation, Roche Diagnostics, Mannheim, Germany) and expressed as milligrams/decilitre (mg/dL)
Time frame: 1 year
Plasma low density lipoproteins (LDL)
Triglycerides, total cholesterol and high densitity lipoproteins are combined to report LDL, according to the Friedewald formula: LDL = CT - (TG/ 5) - HDL
Time frame: 1 year
Plasma lipoprotein A
the plasma content of lipoprotein A is quantified by ELISA and the values are expressed as milligram/decilitre (mg/dL)
Time frame: 1 year
Plasma total lipoprotein B
the plasma content of total lipoprotein B (Apo B48 + Apo B100) is quantified by an immunoturbidimetric assay (Tinaquant; Roche Diagnostics, Mannheim, Germany), The values are expressed as milligram/decilitre (mg/dL)
Time frame: 1 year
Plasma creatinine
standard spectrophotometric assay. Values expressed as milligrams per decilitre (mg/dL)
Time frame: 1 year
Plasma uric acid
Evaluated by an enzymatic procedure, with results expressed in milligrams per decilitre (mg/dL)
Time frame: 1 year
Plasma alanine aminotransferase (ALT)
use of a diagnose kit with values expressed as units per litre (U/L)
Time frame: 1 year
Plasma aspartate aminotransferase (AST)
use of a diagnose kit with values expressed as units per litre (U/L)
Time frame: 1 year
Plasma gamma-glutamyl transferase (GGT)
use of a diagnose kit with values expressed as units per litre (U/L)
Time frame: 1 year
Plasma lactate dehydrogenase (LDH)
L-Lactic Dehydrogenase kit. Results expressed as units per litre (U/L)
Time frame: 1 year
Plasma bilirubin
Spectrofotometric assay. Results expressed as milligrams per decilitre (mg/dL)
Time frame: 1 year
Plasma levels of glutathion (GSH and GSSG)
Glutathione Reductase (GR) Assay Kit. Values expressed as milliunits per millilitre (mU/mL)
Time frame: 1 year
Plasma malondialdehyde
Thiobarbituric acid (TBA) assay and HPLC determination. Results expressed as µmole per litre (µmol/L)
Time frame: 1 year
Plasma ultra-sensitive C-reactive protein
Immunoturbidimetric method. Results expressed as milligrams per litre (mg/L)
Time frame: 1 year
Plasma vitamin B12
chemiluminescence immunoassay (CLIA). Results expressed as picograms per millilitre (pg/mL)
Time frame: 1 year
Plasma thyroid-stimulating hormone (TSH)
ELISA kit. Values expressed as international micro-units per millilitre (µlU/ml)
Time frame: 1 year
Plasma levels of Oleanolic acid
Liquid/liquid extraction and quantification by gas chromatography con flame ionization detection (GC-FID). Values expressed as nanograms per millilitre (ng/mL)
Time frame: 1 year
Serum fatty acids composition
Liquid/liquid extraction and quantification by gas chromatography con flame ionization detection (GC-FID). Values expressed as percentage of the total of fatty acids (%)
Time frame: 1 year
Plasma adiponectin
ELISA kit. values expressed as picograms per millilitre (pg/mL)
Time frame: 1 year
Plasma ceruloplasmin
ELISA kit. values expressed as milligrams per decilitre (mg/dL)
Time frame: 1 year
Plasma leptin
ELISA kit. values expressed as picograms per millilitre (pg/mL)
Time frame: 1 year (measures at the time of recruitment and every three months thereafter)
Plasma resistin
ELISA kit. values expressed as picograms per millilitre (pg/mL)
Time frame: 1 year
Plasma ghrelin
ELISA kit. values expressed as picograms per millilitre (pg/mL)
Time frame: 1 year
Plasma catalase
ELISA kit. values expressed as micromole per milligrams of protein (µmol/mg protein)
Time frame: 1 year
Plasma superoxide dismutase
ELISA kit. values expressed as units per millilitre (U/mL)
Time frame: 1 year
Plasma tumor necrosis factor-alpha (TNF-alpha)
ELISA kit. values expressed as picograms per millilitre (pg/mL)
Time frame: 1 year
Plasma interleukine 1-beta
ELISA kit. values expressed as picograms per millilitre (pg/mL)
Time frame: 1 year
Plasma interleukine 6
ELISA kit. values expressed as picograms per millilitre (pg/mL)
Time frame: 1 year
Triglycerides in VLDL
the VLDL fraction of plasma lipoproteins will be isolated by ultracentrifugation (230,000 × g for 18 h at 4 0C). Lipds will be extracted by a modification of the Folch's method. Triglycerides are determined by HPLC, and results expressed as milligrams per milligram of protein (mg/mg protein)
Time frame: 1 year
Diglycerides in VLDL
the VLDL fraction of plasma lipoproteins will be isolated by ultracentrifugation (230,000 × g for 18 h at 4 0C). Lipds will be extracted by a modification of the Folch's method. Diglycerides are determined by HPLC, and results expressed as milligrams per milligram of protein (mg/mg protein)
Time frame: 1 year
Phospholipids in VLDL
the VLDL fraction of plasma lipoproteins will be isolated by ultracentrifugation (230,000 × g for 18 h at 4 0C). Lipds will be extracted by a modification of the Folch's method. Phospholipids are determined by HPLC, and results expressed as milligrams per milligram of protein (mg/mg protein)
Time frame: 1 year
Fatty acids composition of VLDL
the VLDL fraction of plasma lipoproteins will be isolated by ultracentrifugation (230,000 × g for 18 h at 4 0C). Lipds will be extracted by a modification of the Folch's method. Fatty acids are derivatized to their methyl esters and analyzed by gas chromatography. The results are expressed as percentage of the total of fatty acids (%)
Time frame: 1 year
Apo B in VLDL
Determined by immunoturbidimetry using a commercial kit. Values expressed as micrograms per milligram of protein (µg/mg protein)
Time frame: 1 year
Continuous blood glucose monitoring
FreeStyle Libre subcutaneous system (ABBOTT Diagnostics). Values expressed as milligrams per decilitre (mg/dL)
Time frame: 1 year
Blood Count - hematocrit
Automated blood analyzer. Results expressed as percentage (%)
Time frame: 1 year
Blood Count - red blood cells
Automated blood analyzer. Results expressed as cell count x 10\^6 per microlitre (count x 10\^6/µL)
Time frame: 1 year
Blood Count - hemoglobin
Automated blood analyzer. Results expressed as gram per decilitre (g/dL)
Time frame: 1 year
Blood Count - mean corpuscular volume
Automated blood analyzer. Results expressed as femtolitre (fL)
Time frame: 1 year
Blood Count - mean corpuscular hemoglobin
Automated blood analyzer. Results expressed as picograms (pg)
Time frame: 1 year
Blood Count - leukocytes
Automated blood analyzer. Results expressed as count x 10\^3 per microlitre (count x 10\^3 /µL)
Time frame: 1 year
Blood Count - neutrophils
Automated blood analyzer. Results expressed as count x 10\^3 per microlitre (count x 10\^3 /µL)
Time frame: 1 year
Blood Count - lymphocytes
Automated blood analyzer. Results expressed as count x 10\^3 per microlitre (count x 10\^3 /µL)
Time frame: 1 year
Blood Count - monocytes
Automated blood analyzer. Results expressed as count x 10\^3 per microlitre (count x 10\^3 /µL)
Time frame: 1 year
Blood Count - eosinophils
Automated blood analyzer. Results expressed as count x 10\^3 per microlitre (count x 10\^3 /µL)
Time frame: 1 year
Blood Count - basophils
Automated blood analyzer. Results expressed as count x 10\^3 per microlitre (count x 10\^3 /µL)
Time frame: 1 year
Blood Count - platelets
Automated blood analyzer. Results expressed as count x 10\^3 per microlitre (count x 10\^3 /µL)
Time frame: 1 year
Blood Count - partial thromboplastin time
Automated blood analyzer. Results expressed as seconds (s)
Time frame: 1 year
Blood Count - prothrombin time
Automated blood analyzer. Results expressed as seconds (s)
Time frame: 1 year
Blood Count - coagulative fibrinogen
Automated blood analyzer. Results expressed as milligrams per decilitre (mg/dL)
Time frame: 1 year
Urine pH
Urine pH
Time frame: 1 year
Urine density
Automated urine analyzer. Results expressed as milligrams per millilitre (mg/mL)
Time frame: 1 year
Glycosuria
Automated urine analyzer. Results expressed as milligrams per decilitre (mg/dL)
Time frame: 1 year
Ketone bodies in urine
Automated urine analyzer. Results expressed as millimole per litre (mmol/L)
Time frame: 1 year
Presence of nitrite in urine
Automated urine analyzer. Results expressed as negative or positive
Time frame: 1 year
Urobilinogen
Automated urine analyzer. Results expressed as milligrams per decilitre (mg/dL)
Time frame: 1 year
Urine bilirubin
Automated urine analyzer. Results expressed as milligrams per decilitre (mg/dL)
Time frame: 1 year
Urine creatinine
Automated urine analyzer. Results expressed as milligrams per decilitre (mg/dL)
Time frame: 1 year
Urine albumin/creatinine ratio (UACR)
Automated urine analyzer. Results expressed as milligrams of albumin per gram of creatinine
Time frame: 1 year
Leukocytes in urine
Automated urine analyzer. Results expressed as count x 1 per microlitre (count x 1 /µL)
Time frame: 1 year
Presence of sediment in urine
Automated urine analyzer. Results expressed as negative or positive
Time frame: 1 year
This platform is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.