Yes, one only needs to study and pass to get a degree to be a doctor irrespective of their own medical conditions.
In non-diabetics,it can lead to hypoglycemic coma which can have varied outcome from complete reversal to death.
Increased risk of Heart attack/ Angina/ Stroke, Nerve damage, Kidney damage, Gastroparesis (Nausea/ vomiting) Diarrhea or constipation, Eye damage - blindness, Increased risk of cataract and glaucoma, Foot damage/ amputations, Skin infections, Increased risk of Alzheimer's disease/ Depression/ Hearing impairment.
Insulin reduces blood sugar by helping the cells use glucose.
Diabetes is condition for which exact cause is unknown. Although being unhealthy interms of obesity and other comorbid conditions increase the risk of developing diabetes, there are other causes such as family history/ presence of autoantibodies/ polycystic ovarian syndrome etc which increase the risk.