Type 2 diabetes is an incurable disease, and when left untreated, often leads to dire and severely incapacitating complications.
There are several types of complications:
Macro-vascular disease (macro-angiopathy) hits the coronary arteries with a risk of myocardial infarction, the brain arteries with a risk of stroke and the arteries of the leg with a risk of obliterating arteritis. The cardiovascular risk of diabetic patients is 2 to 5 times higher (depending on other comorbidity criteria) than the general population’s. And, which is even more worrying, ischemic accidents such as infarctions are often silent in diabetes sufferers (little or no thorax pain) and in the event of a stroke, the prognosis is noticeably poorer, especially for younger patients. Lower limb arteriopathies are often compounded by neurological disorders that make them relatively painless, which increases the hazard of developing gangrene. Type 2 diabetes is the prime cause of non-traumatic amputation.
In the small arteries, called the capillaries, the excess sugar in the blood tends to crystallize and obstruct these tiny blood vessels (micro-angiopathy), notably in the retina (diabetic retinopathy) and the kidneys (glomerulopathy), which may lead to chronic kidney failure and dialysis. Type 2 diabetes is the prime cause of non traumatic blindness.
Not very encouraging, is it? Especially when, as often, diabetes is compounded with metabolic syndrome (a combination of overweight or obesity, especially abdominal, high blood pressure and/or dyslipidemia such as high cholesterol or high level of triglycerides) that increases the cardiovascular danger linked to type 2 diabetes. 70 to 90 % of type 2 diabetes sufferers also have high blood pressure and 55 to 70 % also some kind of dyslipidemia. Indeed all the cardiovascular risk factors increase along with the glycemia (sugar blood level) and decrease when it goes down.
Add to this that sugar itself has a direct inflammatory effect on cardiovascular tissues and you’ll understand how bad any glycemic imbalance is for the heart and blood vessels. And these cardiovascular complications begin to develop as soon as the prediabetes stage.
Type 2 diabetes patients also incur neurological diseases (polyneuritis), especially in the peripheral nerves, most often in the lower limbs, that cause pain or on the contrary a desensitization of the feet’s sole.
As a consequence of type 2 diabetes, the genitourinary system may also be damaged, leading notably to erectile trouble in men. Impotence is a common complication of untreated type 2 diabetes, and type 2 diabetes is the prime cause of impotency.
There are also sometimes digestive or vegetative disorders (orthostatic hypotension), bacterial dermatologic, urinary and dental complications. Recent research also hints at an increased risk of dying from kidney pathology (+300%), hepatic pathology (+136%), infectious disease (+139%), and cancer (+25%). There is also a rise in the risk of developing liver cancer (+116%), pancreatic cancer (+51%), ovarian cancer (+45%), cancer of the bladder, the colon or the rectum (+40%), lung cancer (+27%), and breast cancer (+25%).
All in all, diabetes shortens the life expectancy of a 40-year-old American male by an estimated 11,6 years (18,6 if life quality criteria are taken into account); the female figures are respectively 14,3 and 22 years.
All these complications may be prevented in diabetic patients with an efficient control of the blood sugar levels… and even more if one reacts early on, at the prediabetes stage, so as to avoid developing full-fledged type 2 diabetes.
 “Diabetes Mellitus, Fasting Glucose, and Risk of Cause –Specific Death”. The Emerging Risk Factors Collaboration. New England Journal of Medicine, vol. 364, n° 9, p. 829-841.