All Bran is low GI, as is steel cut porridge.
However, many people find they cant tolerate cereals well
I am type 1 and on **** insulin so cant dose adjust and dont touch them with bargepoles.
Best thing to do is to test after you eat - initially at the one and two hour point to determine what certain foods do to you, As a T2 you still make insulin so may tolerate foods better than T1's but a lot of people find insulin resistance much worse in the morning and many T2's avoid starchy foods in the morning.
its really about what suits you and the only way to find out is to test. Have you been given a Blood Glucose monitor (as a T2 I wouldnt be shocked to hear you havent). If not I suggest you get on and some strips to go with it, its the ONLY way to find out what food does to you.
There are many T2 on site who will give much better information than me but testing after eating is the best advice you are going to get, along with keeping a very BIG eye on your carbohydrate intake.