Metformin does not reduce blood sugars much. You need to reduce the amount of carbs you eat. Reduce or avoid breakfast cereals, bread, potatoes, rice and pasta. Avoid fruit juice and fruit such as bananas and grapes. You should then find your blood sugars decreasing.
My blood sugars were 13 at diagnosis. Now they are around 5.3 and that is since I have stopped taking metformin.