My friend is diabetic and his fasting and sugar are coming high. should he add sitagliptin/vidaglipin to his existing med glycomet gp2?

Diabetes: glad you are concerned about friend. What he should do is take his glucose log to his friendly FP or Internist and have his hemoglobin A1C checked to see where his sugars have been for the last 3 months. Then based upon those findings his doctor and he will decide what is the best thing to do. He doesn't need to worry about what medicine needs to be added before he goes.