I am surprised that id you have been Type 2 for 15 years and your blood glucose has been at that high level for all that time that some additional / alternative oral medications have not been suggested before the insulin route as that is not always an easy option if Type 2. Has it been considered that you may be Type 1 or LADA.?
I could be that even though you are saying you are having low carb it is not low enough and you are not tolerating the amount of carbs.
What sort of meals do you have and what would be the amount of TOTAL carbs you have per day.
Testing your blood glucose at home might help you identify particular foods which you are not able to cope with because they increase your blood glucose.
Everybody is different and so their tolerance of particular carbs can be very different. Some are fine with 20g of carb if it is rice but not if bread or potatoes so it could be you are particularly sensitive to what you are thinking is an OK amount of some of the carbs you have.
However there are some people whose Blood glucose levels remain stubbornly high despite a cocktail of oral meds and a very low carb diet and they may then need insulin.