Serum creatinine levels are raised indicating renal failure. In renal failure and hepatic failure --> Metformin is C/I as it |ses the risk of developing lactic acidosis. Contraindicated in patients with an eGFR below 30 mL/minute/1.73 m2. eGFR should be measured annually for patients taking metformin therapy. eGFR is preferred over serum creatinine concentration to assess renal function for a person taking metformin therapy Linagliptin is a DPP-4 inhibitor. Metoprolol is a b blocker.