Acute complications of diabetes are severe and can lead to coma. They are directly related to blood glucose levels and include: Diabetic ketoacidosis, this more common in Type I diabetes and is caused by the breakdown of fatty acids into ketones when there is not enough glucose stored in the cells for energy; Hyperglycemic Hyperosmolar Non-Ketotic Syndrome (HHNS) usually associated with insulin deficiency and dehydration; and hypoglycemia due to too much insulin/oral medication is used or too little glucose. All three of these conditions are emergencies and failure to treat quickly can lead to coma and/or death.

Chronic complications of diabetes involve changes in blood vessels, tissues and organs. Consistently high blood glucose levels can cause a hardening and thickening of the blood vessels which can lead to many other diseases. Cardiovascular disease involves both the large and small blood vessels that supply blood to your heart. Cerebrovascular disease involves the blood vessels that supply oxygen and nutrients to your brain. Diabetic Retinopathy is caused by a blockage of blood vessels within the eye that leads to the blood vessels leaking into the retina. This eventually leads to blindness.

Pathological changes within the kidneys can lead to Diabetic Nephropathy or Kidney Failure. Diabetes Mellitus is the number one cause of kidney failure and develops in 40 to 50% of all diabetics. It is also the most common cause of death in Type I diabetics.

Diabetes can also cause damage the peripheral nervous system (arms & legs) causing Diabetic Neuropathy. This leads to loss of nerve function that either results in constant pain or loss of feeling. Erectile Dysfunction is also a chronic condition associated with diabetes. Causes are a combination of vascular and neurological damage.