Although stress doesn't cause diabetes, it can have a negative affect on the condition by changing blood glucose levels directly or indirectly. Blood glucose levels can be directly altered from stress hormones, or stress can indirectly affect diabetes through poor lifestyle choices. Often, people under stress don't take good care of their health. They tend to exercise less, eat a poor diet and drink more alcohol.

Medical research has found that mental stress either causes glucose levels to rise or go down in people with type 1 diabetes, but in most people with type 2 diabetes, mental stress causes glucose levels to rise. On the other hand, physical stress that results from illness or injury causes higher glucose levels in people with both types.