You cannot simply substitute Vildagliptin by increasing the dose of Glimepiride. Their mechanism of action is different and may lead to adverse effects. You need to visit your doctor and express the concern regarding the cost of Galvusmet. He will review your reports and give you an appropriate, cost effective alternative prescription.
Next Steps
Do not change anything by yourself. Consult your physician/diabetologist with the reports and your concern regarding the cost of the medications prescribed.