If he was diabetic and had very high or very low blood sugar, he might have taken risks he normally wouldn't have. My mom is diabetic and I am hypoglycemic; weird stuff happens when the blood sugar is off.

Not wearing his helmet, exiting onto a semi-truck weigh station ramp, driving into a closed gate; all could be blood sugar related.

Berkeley, I am so proud of you for handling the situation the way you did. Whatever lead that biker to crash, you certainly helped save him!