A 41-year-old man has uncontrolled T2DM for 3 years. He also has hypertension and dyslipidemia. His medications are metformin, gliclazide, perindopril and atorvastatin. His investigations reveal normal CBC, renal function and liver enzymes HbA1c is 8.5%, LDL 90mg/dl and normal urinary albumin creatinine ratio, in order to optimize his glycemic control, a GLP-1 receptor agonist (Liraglutide) will be added to his regimen. Which of the following is a serious side effect of GLP-1 receptor agonist?