Why Do People Insist That Diabetes Is Always As A Result Of Consuming Too Much Sugar And Being Overweight?

Why do people insist that diabetes is always as a result of consuming too much sugar and being overweight? At the time I was diagnosed I was not overweight, did not consume vast amounts of sugar, sugary foods, fat or junk foods. I ate, as I always have, and still do, a healthy, balanced diet based on wholefoods, fruit and vegetables. I have never smoked and walked at least 5 miles 6 days a week. I have type 2, and was aged 56 when diagnosed. It is very well controlled, with none of the associated complications. I am taking tablets and not insulin. In response to some answers, I am not aware of any blood relatives with diabetes. I had been going through a time of severe stress for a while and when diagnosed my then doctor thought that may have been the trigger, something had to give . When I walk I build up a good steady pace, even uphill. I used to walk to and from work, each way took about 35 to 40 mins. depending on the weather. I walk or cycle now as much as I can. The tablets I take are metformin and rosiglitazone combined and on low dosage.