You are completely correct.
Diabetes, along with all dis-eases are emotionally rooted, rather, the source of the emotion, rooted.
If everyone would take the time for self discovery, located the root of the cause of the fear/negative emotions/feelings and remove it; the body would naturally come back into balance. Dis-Ease is just an imbalance that the individual has with his/her self.
As is always the case. These Stresses that stem from the lies this root is seated in, manifests itself in our bodies as tension and resistance. Deep Tissue body work, reflexology, acupressure, stretching are all wonderful mechanisms to help the release of the paradigms that keep people in a state of dis-ease.
Always it must start internally, or the in-balance will never get removed. Only smoothed over, covered up until enough has built up on it to become an issue once again.
You are Absolutely Correct, and very important, for those who are diabetic, to see in themselves those traits that you have found common. I have seen these as well, In people with diabetes. How interesting is that!