Effect of Anti-diabetic Drugs on Glycemic Variability

Overview

Objectives Primary objective: To access the change from baseline to week 12 in MAGE index of glycemic variability measured by CGMS for dapagliflozin versus. gliclazide MR. Secondary objectives: 1. Change from baseline to week 12 in glycated hemoglobin A1c (HbA1c), fasting plasma glucose, postprandial glucose and achievement of HbA1c ≤6.5% and \<7% at the end of the study) for dapagliflozin versus gliclazide MR. 2. Change from baseline to week 12 in glycemic variability defined by the interquartile range (IQR - interval between 25th and 75th percentiles) measured by CGMS for dapagliflozin versus gliclazide MR. 3. Change from baseline to week 12 in glycemic variability measured by the Standard Deviation of the mean glycemia (SD) measured by CGMS for dapagliflozin versus gliclazide MR. 4. Change from baseline to week 12 in glycemic variability measured by the Coefficient of Variation (CV) measured by CGMS for dapagliflozin versus gliclazide MR. 5. Change from baseline to week 12 in the time spent on hypoglycemic range (glycemia \<70mg/dL) measured by CGMS for dapagliflozin versus gliclazide MR. Study design This is a single-center, prospective, randomized, open-label, comparative, phase IV study to compare the effects of gliclazide MR and dapagliflozin on Glycemic Variability in patients with Type 2 Diabetes Mellitus (T2DM). All patients should be treatment naïve or receive standard of care therapy for T2DM as well as for co-morbidities based on accepted guidelines and local best practices. Target patient population Approximately 120 patients with T2DM will be randomized from study site. Patients who were treated with metformin only and had inadequate glycemic control at the time of enrollment as well as treatment naïve or non-medically treated (e.g., diet) patients, will be enrolled and receive either dapagliflozin 10mg qd or comparator gliclazide MR 120mg qd in addition to standard of care treatment for T2DM and co-morbidities. Investigational product, dosage and mode of administration Dapagliflozin 10mg tablets administered orally once daily for 12 weeks. Comparator, dosage and mode of administration Gliclazide MR 60mg tablets administered orally, 2 tablets once daily for 12 weeks. Duration of treatment The treatment with study medication or comparator will have a total duration of 15 weeks.

INTRODUCTION Dapagliflozin is a highly potent, selective, and reversible inhibitor of sodium-glucose cotransporter-2 (SGLT2), the major transporter responsible for renal glucose reabsorption.1 Dapagliflozin lowers plasma glucose by inhibiting the renal reabsorption of glucose and by promoting its urinary excretion in patients with type 2 diabetes mellitus (T2DM). Gliclazide MR is a highly potent and selective sulphonylurea considered by specialists a reference in this class, because of its low risk of hypoglycemia and no increasing in cardiovascular mortality. Gliclazide MR increases the physiological mechanism of insulin secretion, thus reducing the postprandial and fasting glucose levels in patients with type 2 diabetes. There is an increasing large amount of evidences showing that rapid fluctuations in blood glucose and high glycemic variability may have an important role in the development of diabetes complications. Cardiovascular disease, endothelial dysfunction and oxidative stress are common complications among patients with type 2 diabetes and glycemic variability may be an important factor in their development. Previous studies have shown that vildagliptin, a dipeptidyl peptidase 4 inhibitor (DPP-4 inhibitor), could improve not only the mean blood glucose but also the 24-hour glucose fluctuation by restoring the physiological pattern of insulin and glucagon secretion. SGLT-2 inhibitors are novel anti-diabetic drugs and currently there are not published studies that evaluated their effects on glycemic variability calculated by the widely used methods like mean amplitude of glycemic excursion (MAGE), standard deviation of the mean glycemia (SD), coefficient of variation (CV) and interquartile range (IQR). The aim of the current study is to compare the effect of gliclazide MR with dapagliflozin on the glycemic variability using a continuous glucose monitoring system (CGMS) to determine MAGE, SD, CV and IQR. 2\. METHODOLOGY 2.1 Study Population (Target population of Clinical Trial Subjects) A total of 120 patients with documented Type 2 Diabetes will be enrolled, considering an expected screening failure rate of 30% (n=22) and an expected dropout rate of 8% (n=10), based in previous studies conducted in our center using similar populations and period. We estimate that 88 (44 in each group) subjects will complete all protocol procedures. Per-protocol analysis will be restricted to the participants who fulfill the protocol in terms of the eligibility, interventions and outcome assessment. To be as close to a real life scenario as possible, this clinical trial will include subjects patients who were treated with metformin only and had inadequate glycemic control at the time of enrollment as well as treatment naïve or non-medically treated (e.g., diet) patients. 2.2 Investigational Product, Posology and Method of Administration The active treatment will include a 10 mg dose of dapagliflozin orally once a day. 2.3 Comparator, Posology and Method of Administration As comparator, gliclazide MR will be administered at a dose of 120 mg orally once a day. 2.4 Study Duration The study will have an expected total duration of 15 months (12 months for recruitment and 12 weeks of active treatment). 2.5 Methods and Assessments Patients will be randomized after revision of inclusion and exclusion criteria. Randomization will occur in a 1:1 manner using a validated computerized system until completion of 88 randomized patients. Patients from group 1 (n\~44) will receive the study medication (dapagliflozin) and the ones from Group 2 (n\~44) will receive the comparator gliclazide MR on top of usual treatment for type 2 diabetes. Treatments with the study medication or comparator will last 12+/-1 weeks. All patients for both groups will receive the same guidelines about the diet (caloric and macronutrient contents) and physical activity by the same dietitian from the study site at the beginning of study. A "blinded to the patient" Continuous Glucose Monitoring System (CGMS, iPro2 (TM) with Enlite-Sensor (TM); Medtronic Mini-Med Inc., Northridge, California, USA) will be inserted subcutaneously. The sensor is a glucose oxidase-based platinum electrode that is inserted through a needle into the subcutaneous tissue of the anterior abdominal wall and allows up to 288 glucose readings per day. The CGMS will be placed for 72 hours at beginning (in the last three days of run-in phase) before starting the study medications and again at the end of the study in the last three days of the study treatment. The validated softwares Glyculator (TM) or EasyGV (TM) will calculate the glycemic variability parameters MAGE, SD and CV IQR will be calculated by the software Captür-AGP (TM). Biochemical markers of glycemic control (HbA1c, fasting glucose and postprandial glucose) will be determined at beginning and at the end of the treatment period. Each patient will maintain regular visits to his assistant doctor. At the end, the two groups will be compared according to the following parameters calculated based on results obtained on both CGMS tests, blood samples and patient Clinical Research Form (CRF) * Glycemic variability parameters: MAGE, SD, CV and IQR * Glycemic controls parameters: HbA1c, fasting glucose and postprandial glucose * Exploratory variables: incidence of urinary tract Infection and genital infection and incidence of volume depletion. 2.6 Sample size and Statistical methods To determine the sample size and obtain a clinical and statistical significant result in the primary variable (difference \>14.5mg/dL on glycemic variability), it was used MAGE (mean amplitude of glycemic excursion). As MAGE is glycemic amplitude measured in mg/dL, it was arbitrarily set a difference of ≥ 14.5, which may be clinically important for the patient as judged by the study center team and its expert consultants. There is not a good study of T2DM patients that establishes which MAGE difference or improvement could be significant to prevent diabetes complications. Sample size was calculated based on the provided parameter: significance level (adjusted for sidedness) = 0.025, standard deviation for MAGE = 24mg/dL, power = 0.8, and a between-group difference in mean MAGE equal to 14.5 mg/dL. The variable calculated was the total number of patients. A total of 44 patients in each group (dapagliflozin 10 mg or gliclazide MR 120 mg) must complete this two-treatment parallel-design study. Considering an expected screening failure rate of 30% (n=11 per group) and an expected dropout rate of 8% (n=5 per group), based in previous studies in our center using similar populations and period, a total of 60 patients per group (120 total) will be enrolled. Demographic and baseline characteristics will be represented by distributions of frequency and summarized statistics based on the dataset, both for each treatment group and all clinical trial subjects combined. The main baseline characteristics will be presented. ANCOVA will be used with adjustment for baseline values. For primary and secondary variables, all quantitative, it will be used Student's t-test or Mann-Whitney test for the statistical evaluation and comparison between groups. In all tests, it will be used the significance level of 5% or p\<0.05. 2.7 Study Design and Rationale This is a single-center, Prospective, Randomized, Open-label, Comparative, Phase IV Study to compare the effects of gliclazide MR and dapagliflozin on Glycemic Variability in patients with Type 2 Diabetes.