Which of the following anti-diabetic drugs can be used safely in renal failure?

Metformin is excreted the kidney and hence urine MICRAL (Microalbuminuria) test and KFT should be done to estimate GFR of the kidney. Failure to perform these tests can result in accumulation of metformin and development of metabolic acidosis. Both Sitagliptin and Canagliflozin (SGLT-2 inhibitor acting on PCT) are metabolised by the kidney. Linagliptin has non-linear pharmacokinetics and unlike other DPP-4 inhibitors, has a largely non-renal excretion route. It is excreted unchanged in the faeces and urine. The effective half-life is 12 hours.