What Causes Enlarged Kidney Along With Elevation Of Creatinine Levels?

My father is suffering with kidney disease, Diabetes and Blood pressure since couple of days. He took all the body tests as our doctor suggested. It looks his kidney enlarged little bit and his CREATININE is 2.3 as it is showing in the report after his blood test. I assume that he is falling in 1st stage of Kidney disease. Please suggest us that what would be the complete food diet for him and other your valuable precautions. Thanks. Dina.