I was diagnosed with type 2 at the start of the year and was prescribed Metformin until yesterday, I was taking 3 x 500mg tablets daily (started with 1 x 500mg and worked up to 3 tablets daily) but due to the side effects that started last week, I've been told to stop taking these immediately and to move onto 1 x 25mg Sitagliptin tablet daily. If these are intended to have the same result, is 25mg of one equivalent to 500mg (or 1500mg) of the other?