I am a T2 (diet controlled) in my own personal experience as a vegetarian from birth - approach 4 didnt work! I followed a low fat, high fiber vegetarian (vegan for many years). I ate lots of fruit and veg, filled up on higher fiber carbs such as brown rice, wholegrain pasta porridge etc, refused to eat anything that was more than 5% fat. I still became T2.
After I was diagnosed the NHS dietitian said I was following a "perfect diet" and should continue. GP just told me I was going to take metformin.
I refused the meds , bought my own meter and started to test how my body reacted tot he foods I ate. I was shocked at how high the spoke was after my "healthy porridge made with skimmed milk", the horror of the spike after my low fat wholewheat veggie lasagne.
After reading lots of the info on this forum, and continued testing with my meter it was very evident that the low carb approach worked for me. It did take me a long time to overcome my fear (years of brainwashing) of low fat.
I now eat a vegetarian low carb healthy fat diet. My blood glucose levels are controlled, I have no diabetic complications, I have never needed any medication (other than a multivitamin to ensure I get enough B12 and iron) my cholesterol levels are normal (lowish). My only "problem" is not loosing too much weight each week - yes really!! despite eating cheese, clotted cream, chocolate etc every week.
This approach works for me, we are all individuals, the only way I found what worked for me was to test, test test, I still test but dont get too worried about small changes. (I have discovered that my BG levels follow hormonal changes (monthly cyces and ovulation) and are raised a few days before I come down with a cold/virus etc.
Have a good look around the forum, have a look at the dietdoctor website for great low carb ideas (there are pictures on the site for lower carb choices - so useful!)
Keep asking for help