If symptoms are left untreated there can be severe complications, some of them can occur at any time and are called Acute complications and there are ones that happen over a prolonged period of time and are called Chronic complications
Chronic Complications
Eye Damage: High blood glucose levels can lead to severe damage to retina known as Retinopathy which can affect the eyesight
Kidney Problems: Diabetes can lead to damage to your kidneys (nephropathy) which will ultimately affect clearance of toxic wastes from your body.
Nerve Damage: Diabetes might result in nerve damage (neuropathy) that will cause burning, numbness and pain in extremities specially in the feet (peripheral neuropathy).
Heart attack and Stroke: Uncontrolled diabetes can result Heart attack and Stroke that is mainly due to damage to the large blood vessels (Diabetic macro vascular disease)
Infections: poorly controlled diabetes will always lead to Fungal as well as Gum disease.
Acute Complications
Hyperglycemia: Excessively high blood glucose levels
Hypoglycemia: When the blood glucose levels are too low
Hyperosmolar Hyperglycemic state (HHS): It’s a life threatening state which results in severe dehydration because of intracellular water depletion and subsequent osmotic diuresis.
Diabetic Ketoacidosis (DKA): Prolonged high levels of glucose result in increased buildup of ketones in patient muscle and adipose tissue that ultimately results in blood becoming acidic. It’s a life threatening condition in which the patient needs to be addmitted in the hospital.