Type 2 diabetes. Is it time to switch to insulin injections?

My mother is type 2 diabetic and she takes oral medication.(Metformin hydrochloride + glibenclamide 500MG BD).

The problems is she always felt dizzy and nauseous.

1. Is this caused by the side effects of medication that she took?.
Her BG reading was always high at 20.0 mmol/l (360 mg/dl).

My other question is...

2.Does she need insulin injections?. Because she has T2 diabetes for over 15 years.

I agree, what is her A1C? Her CDE or pharmacist, may be of assistance to her as far as side effects and other medical issues. Nancy