Yes! Stress does cause diabetes especially the lifestyle-related type of diabetes (Type 2). The blood sugar level of a human is directly proportional to the functionality of the stress hormone known as cortisol. If one's sugar level is high the stress hormone will also be high because a stressed individual is mentally unstable, and this, in turn, affects his body's blood sugar level due to constant disturbances and uneasiness playing out on his mind. But if the blood sugar level is normal, the stress hormone will remain stable too. The reason for this relationship is that the individual that is stressed would not bother to take care of his mental health to the point he is not even worried about going to check his blood sugar level in the hospital. Mind you he is overwhelmed by life problems and the only thing that could be on his mind is looking for ways to ease the stress which could be the use of alcohol or drugs.