Effects of Liraglutid, Dapagliflozin and Acarbose on the Cognitive Function, Olfactory Function, and Odor-induced Brain Activation in Overweight/Obese T2DM Patients Controlled Inadequately With Metformin Monotherapy.

This is a prospective, randomized, open label, parallel, 16-week study to explore and evaluate the therapeutic effects of liraglutid, dapagliflozin and acarbose on the cognitive function, olfactory function, and odor-induced brain activation in overweight/obese patients with type 2 diabetes mellitus(T2DM) inadequately controlled with metformin monotherapy.

This is a prospective, randomized, open label, parallel, 16-week study to explore and evaluate the therapeutic effects of liraglutid, dapagliflozin and acarbose on the cognitive function, olfactory function, and odor-induced brain activation in overweight/obese patients with T2DM inadequately controlled with metformin monotherapy.We have 1 principle investigator, 6 sub-investigators and 1 nurse in research centre. The sub-investigators will screen in the outpatient and inpatient departments to enroll 87 patients (29 for each arm) totally with the inclusion and exclusion criteria in 12 months. The patients will be randomized at a 1:1:1 ratio into liraglutid, dapagliflozin and acarbose treatment group with a computer-generated random order. All patients will also continue on their existing dose and regimen of metformin throughout the study. At the baseline, clinical information collection, 100g-steamed bread meal test, biochemical measurement, body composition analysis, cognitive assessment, olfactory test and functional magnetic resonance imaging(fMRI) scan will be conducted for all patients. During the treatment period, visits at 4-week intervals will be performed to evaluate the safety of drugs and adjust the dose of metformin if hypoglycaemia occurs; meanwhile, fasting and 2-hour postprandial plasma glucose assayed by fingerstick, physical examination, and olfactory test will be conducted. At the end of the study, all of the assessments will be performed again for all recruited subjects, including early withdrawal patients.

Eligibility Criteria:
Inclusion Criteria:

* Age ≧ 40 and ≦75 years old
* T2DM patients controlled with metformin monotherapy with stable, maximum tolerated doses (≧1500mg/d, ≧12 weeks)
* HbA1c\>7% and ≤9%
* Body mass index(BMI) ≥25kg/m2 and with stable weight during previous 3 months
* Right handedness
* Possessed over 6-year education
* Provision of informed consent prior to any study specific procedures
* Mini-Mental State Examination (MMSE) \>24

Exclusion Criteria:

* Allergies to research drugs
* Treated with glucagon-like peptide-1 receptor agonists, dipeptidyl peptidase-4 inhibitors, sodium-glucose cotransporter 2 inhibitors, insulins, and glycosidase inhibitors in the previous 6 months
* Moderate to severe renal dysfunction defined as estimated glomerular filtration rate(eGFR)\<60ml/min/1.73m2 ( eGFR was estimated by CKD-EPI creatinine equation using an online calculator).
* Hepatic insufficiency
* A history of neurological and psychiatric disorders, nasal pathologies, abnormal thyroid, pancreatitis, repeated urinary tract infection, chronic gastrointestinal dysfunction, any disease that may worsen by intestinal flatulence, alcohol or substance abuse, steroid treatment
* Any acute disease
* Inability to undergo tests or MRI scanning
* Pregnant or lactating women
* Participating in other clinical trials at the same time or within 6 months prior to the start of the trial