Steve, Think of it this way, you need to consume 3500 calories per week less than your basal to lose half a kg or burn it in exercise.Do both and you get 1kg a week, in fact at 141kg a bit more. Basal varies with age, height and weight but say at age 45 and 180cm then your basal is around 2600calories a day. So if you keep to 2100 calories a day diet and do 500 calories exercise you will lose 1kg a week. Just walk for 90 minutes each morning for exercise burn. If you dont have time then do 45 mins and only consume 1850 calories a day.
Use an aid like 'myfitnesspal' religiously, and no alcohol. Your diabetes problem is simply 'insulin resistance', metformin can help but you simply have to lose weight to combat this or you are likely to complications very early, not only from diabetes but all the other conditions that gross obesity causes.
I was 128kg and am on my way down to a target of below 90kg. I'm 61 and would like to see my grandchildren for a few more years.