Metformin

What was your HbA1C at diagnosis and what is it now? If you follow a low carb diet then your blood sugars can be reduced into the non-diabetic range within 9 months. If your blood sugars are low then you don't need Metformin. Just taking Metformin without changes to your diet won't lower your blood sugars below the diabetic threshold.

Metformin can cause problems with lactic acid clearing in the liver.

You need to get a blood glucose monitor and test before and two hours after foods. Best to avoid high carb food like breakfast cereals, bread, potatoes, rice and pasta. Also avoid fruit juice and fruit like bananas and grapes. You should find your blood glucose reading dropping. Ideally you want 4-7 before and no more than 8.5 two hours after meals.

You need to be careful with gliclazide that your blood sugars go too low and you get hypos once you eat low carb. If so, reduce the Gliclazide. Unfortunately GPs just prescribe pills and allow people to have years of high blood sugars which can lead to retinopathy, neuropathy and various other complications. The experience of people on these forums is that diet is the most important thing to treat type 2 diabetes.

I am not on metformin. However, liver function is one of the regular tests I have as there is more risk of liver problems with diabetes regardless of treatment.
I assume this is a standard test so it should be being checked for you.

My father's hepatologist took my father off metformin and put him on Lantus and Jardience. It wasn't the metformin that was the problem but the compound that that goes with it.