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?
The two drugs do not work in the same way, metformin works by limiting how much stored sugar your liver releases and reduces the absorption of sugar through the stomach.
Sitagliptin works by increasing the amount of insulin released by your pancreas, so the dosage for each one will be different.
Have you thought about changing your diet? All medicine comes with side effects, if you can alter your diet there is a chance you could maybe manage without any medication.
Have a look at the link for the Nutritional thingy at the bottom of my post.
Oh and welcome to the forum