"There has been a lot of research that suggests that depression relates to diabetes. But it remains possible that this association is really due to an 'underlying third factor' that is associated with both depression and diabetes. For instance it is possible for a person to first develop an eating disorder, then to develop depression and then diabetes. If you would look only at depression and diabetes you would conclude that it is due to depression. But once you look at the whole spectrum of mental health problems you get a more complete picture.”