A 60 year old female patient with history of Polyuria upto several times a day including night, polydipsia, burning sensation of the whole body. On examination she has mild pallor, blood pressure 160/80, heart rate 103/min, temperature normal,respiratory rate normal.

Her RBS seen around 20 days back was 90mg/dl. What are the diffrential diagnosis to keep in mind in this case while investigating her?