Yes it is true that mental stress is responsible for developing diabetes.
Why stress is responsible for diabetes?
How stress can develop diabetes?
Stress is associated with diabetes is very true, whenever someone is in stress, his body produces a hormone noradrenalin an anti stress hormone, but this hormone has negative effect on secretion of insulin, secretion of insulin is decreased, and in event a person stays in regular stress his body may develop resistance to insulin or the insulin produced may not be sufficient to take care of increased blood glucose level.
A consistent higher amount of blood sugar in blood develops other complications which turns in to irreversible changes in to body tissue insulin receptors that turn in to resistant one, they require more qty of insulin to reduce blood glucose level, Beta cells in Pancreases which produce Insulin will further lose their activity many times autoimmune diseases and some drugs are responsible for developing diabetes. Following image will explain in details how stress is responsible for diabetes.