Study Design and Participants
This study was a 9-month randomized trial designed to evaluate the efficacy of antidiabetic traditional treatment + dulaglutide when compared with traditional antidiabetic treatment alone in patients with type 2 diabetes.
Traditional antidiabetic treatment was considered treatment with metformin or metformin plus sulfonylurea or basal insulin plus metformin.
Men and women (aged ≥50 years) with established or newly detected type 2 diabetes whose HbA1c was 9.5% or less on stable doses of up to two oral glucoselowering drugs with or without basal insulin therapy.
The key exclusion criteria for patients screened were: type 1 diabetes, previous GLP-1 receptor agonist treatment, treatment with more than half of the sulphonylurea maximum dose at screening, current insulin or thiazolidinedione use, chronic systemic glucocorticoid use, or gastric emptying abnormality.
Further exclusion criteria were: an eGFR18 less than 15 mL/min per 1·73 m², cancer in the last 5 years, severe hypoglycemia in the last year, life expectancy less than 1 year, a coronary or cerebrovascular event within the last 2 months, and plans for revascularization
A common protocol was approved by the institutional review board, and the study was performed in accordance with the principles of the Declaration of Helsinki and Good Clinical Practice (29).
Each patient provided written informed consent before participation.
The trial has been registered on Clinical Trials.gov [ClinicalTrials.gov Identifier: NCT03824002].
We used the revised criteria of the American Diabetes Association to diagnose type 2 diabetes (T2DM), using a value of fasting blood glucose ≥126 mg/dl or a clinically based algorithm that considered, presenting weight and symptoms, age at onset, onset of insulin treatment, family history and history of ketoacidosis (30) .
Hypertension was diagnosed according to the 2013 ESC-ESH criteria (31).
Dyslipidemia was defined as TG level ≥150 mg/dl and HDL cholesterol level (<40 mg/dl) regardless of the patient's gender (32)
Randomization
After a 2-week placebo screening and run-in period, eligible patients were randomly assigned to undergo traditional antidiabetic treatment plus dulaglutide or traditional antidiabetic treatment alone using a computer-generated random sequence (1:1) with dulaglutide administered once weekly for 9 months. Investigators involved in clinical data collection and measurement of outcome variables were not directly involved in the patients’ treatment and were masked to the randomization process. The randomization code was maintained only at the central data facility and was not broken until all data analysis was complete.
Procedures
Subcutaneous dulaglutide was initiated at the full dose (1.5 mg/day weekly).
During the treatment period, participants in both groups were instructed to inject study drug on the same day at approximately the same time, each week. Participants were visited at 2 weeks, 3 months, and 9 months. At every visit, assessments included cardiovascular events, adverse events, vital signs, and periodic questionnaires, laboratory tests electrocardiograms (ECGs) and vascular damage index assessment (see above). Investigators were advised to promote a healthy lifestyle and to manage glucose concentrations according to local guidelines. Management of blood pressure, lipids, other cardiovascular risk factors, and medical conditions was at the discretion of the study investigator.
Hypoglycemia was defined as a blood glucose concentration ≤3.9mmol/l. Severe hypoglycemia was defined as an episode that required the assistance of another person to actively administer carbohydrate, glucagon or other resuscitative actions. Patients were allowed to initiate rescue therapy for severe, persistent hyperglycemia according to predefined thresholds on fasting blood glucose for at least 2weeks with no readily identifiable cause.
PWV Measurement
Carotid-femoral PWV was assessed in the supine position using the automatic device (SphygmoCor version 7.1) that evaluated the time delay between the rapid upstroke of the carotid and femoral artery pulse waves. The distance between the two arterial points was measured using a tape measure on the surface of the body. PWV was valuated as the distance traveled by the arterial pulse wave (meters) divided by the time delay between the two arterial points (seconds), thus expressed as meters per second.
Pulse Wave Analysis
We used the Applanation tonometry to record radial artery pressure waveform continuously, and mean values of ≥2 screens of pulse waves of good quality were used for analysis. In consideration of the collected data, an averaged radial pressure waveform was created and a corresponding aortic pressure waveform and BP calculated by the validated transfer function (SphygmoCor version 7.1). The aortic pressure waveform was utilized to calculate the AIx (difference in height between the first and second systolic peaks expressed as a percentage of PP).
RH-PAT
The principle of RH-PAT has been described previously by some researchers (19). In sum, a blood pressure cuff was positioned on 1 upper arm, while the contralateral arm served as a control. PAT probes were positioned on one finger of each hand. After a 5-min equilibration period, the cuff was inflated to 60 mm Hg above the systolic pressure or 200 mm Hg for 5 min and then deflated to induce reactive hyperemia. Reactive hyperemia is a temporary increase of blood flow on an area as result of induced ischemia and express “the health state” of endothelium.
The RH-PAT data were digitally analyzed online by Endo-PAT2000 software version 3.0.4. The RH-PAT index (RHI: reactive hyperemia index) reproduces the range of reactive hyperemia and was measured as the ratio of the mean amplitude of PAT signal over 1 min starting 1.5 min after cuff deflation (control arm, A; occluded arm, C) divided by the mean amplitude of PAT signal of a 2.5-min time period before cuff inflation (baseline) (control arm, B; occluded arm, D). Thus RH-PAT index (RHI) = (C/D)/(A/B) x baseline correction. A value of RHI < 1,67 indicated endothelial dysfunction
Vascular damage markers evaluation
PWV, Aix and RHI were measured at admission and at every three- and nine-month follow-up visit assessment.
Endpoints of the study
Metabolic Efficacy endpoints were:
- change from baseline in body weight at three and nine-month follow-up;
- change from baseline in BMI at three and nine-month follow-up
- change from baseline in FPG at three and nine- month follow-up
- change frombaseline in HBa1C at three and nine-month follow-up
- change frombaseline in serum total cholesterol at three and nine-month follow-up
- change from baseline in serum LDL cholesterol at three and nine-month follow-up
- change from baseline in serum HDL cholesterol at three and nine-month follow-up
Vascular Efficacy endopoints were:
- change from baseline in RHI value at three and nine-month follow-up
- change from baseline in PWV at three and nine-month follow-up
- change from baseline in Aix at three and nine-month follow-up
Outcomes
The first primary objective was to show the superiority of dulaglutide vs traditional treatment on metabolic variable change (fasting plasma glucose, HBa1C, total cholesterol, LDL-cholesterol, HDL-cholesterol, triglycerides) from baseline at a three- and a nine-month follow-up.
The second primary objective was to show the superiority of dulaglutide vs traditional treatment on some vascular health indexes such as markers of arterial stiffness (PWV, Aix) and of endothelial function such reactive hyperemia index (RHI) change from baseline at three- and nine-month follow-up.
Statistical Analysis
The sample-size of at least 40 randomized patients was selected to provide >99% power to demonstrate superiority of dulaglutide to placebo. This assumed a true mean difference in metabolic and vascular variable mean value change from baseline between dulaglutide and placebo of 0.8%, a common standard deviation of 1.1%, a one-sided significance level of 0.025, and a 9% drop-out rate between randomization and week (26). Moreover, the given sample-size provided at least 90% power to confirm non-inferiority of dulaglutide to liraglutide with a margin of 0.4%.
Continuous data are expressed as mean ±SD, unless otherwise specified. Intergroup differences were assessed by the chi-square test or Fisher exact test, as needed for categorical variables, and by the independent Student t test for continuous parameters if the data were normally distributed. Intragroup differences were performed by repeated measures analysis of variance (ANOVA) and post hoc analysis with the Tukey test was used to determine if there were any intra-group differences in pairs.
Data were analysed by IBM SPSS Software 22 version (IBM Corp., Armonk, NY, USA). All p-values were two-sided and p<0.05 was considered statistically significant.