we do not know how hard people have tried to lose weight. There are a number of us on here, including myself, who try very hard to lose weight, year after year, continuously, and our bodies will not let go of the weight.
Up until 2012 I followed the dietary advice of the NHS and continually dieted as well, and my weight problem got worse as it increased my insulin resistance. Since then, my weight gain has stopped with me doing medium fat, lowish carbs. I have even lost 2 stones over the past 5+ years but, despite my best and ongoing efforts, I am stuck at morbidly obese.
weight gain in type 2 diabetics is a symptom and consequence of their diabetes, not the cause. I suspect many of the people we see in the street and elsewhere who are fat may have insulin resistance issues which are neither recognised or diagnosed. In which case, their efforts to diet the 'traditional' way are counter productive. Then they are subject to comments from others about not trying hard enough or not following medical advice etc.
I dont know about England, but here in Wales it is rare, very rare, to get a blood sugar test unless there are other issues going on, by which time the IR can be decades old. Quite apart from all the slim undiagosed type 2's.