Diabetes is a chronic, life–long condition that requires careful control. Without proper management it can lead to various complications such as cardiovascular disease, kidney failure, blindness and nerve damage.

Short–term complications
Low blood sugar (hypoglycaemia)
A person who takes insulin is going to face the problem of their blood sugar falling too low at some point (because they have overestimated the insulin they need, have exercised more than anticipated or have not eaten enough). Hypoglycaemia can be corrected rapidly by eating some sugar. If it is not corrected it can lead to the person losing consciousness.

It is important that the person with diabetes recognises the signs of hypoglycaemia.

Ketoacidosis

When the body breaks down fats, acidic waste products called ketones are produced. The body cannot tolerate large amounts of ketones and will try to get rid of them through the urine. However, the body cannot release all the ketones and they build up in your blood, causing ketoacidosis. Ketoacidosis is a severe condition caused by lack of insulin. It mainly affects people with type 1 diabetes.

Lactic acidosis
Lactic acidosis is the build up of lactic acid in the body. Cells make lactic acid when they use glucose for energy. If too much lactic acid stays in the body, the balance tips and the person begins to feel ill. Lactic acidosis is rare and mainly affects people with type 2 diabetes.

Bacterial/fungal infections
People with diabetes are more prone to bacterial and fungal infections. Bacterial infections include sties and boils. Fungal infections include athlete’s foot, ringworm and vaginal infections.

Long–term complications
Eye disease (retinopathy)
Eye disease, or retinopathy, is the leading cause of blindness and visual impairment in adults in developed societies. About 2% of all people who have had diabetes for 15 years become blind, while about 10% develop a severe visual impairment.
IDF fact sheet on diabetes and eye disease

Kidney disease (nephropathy)
Diabetes is the leading cause of kidney disease (nephropathy). About one third of all people with diabetes develop kidney disease and approximately 20% of people with type 1 diabetes develop kidney failure.
IDF fact sheet on diabetes and kidney disease

Nerve disease (neuropathy)
Diabetic nerve disease, or neuropathy affects at least half of all people with diabetes. There are different types of nerve disease which can result in a loss of sensation in the feet or in some cases the hands, pain in the foot and problems with the functioning of different parts of the body including the heart, the eye, the stomach, the bladder and the penis. A lack of sensation in the feet can lead to people with diabetes injuring their feet without realising it. These injuries can lead to ulcers and possibly amputation.

Diseases of the circulatory system
Disease of the circulatory system, or cardiovascular disease, accounts for 75% of all deaths among people with diabetes of European origin. In the USA, corony heart disease is present in between 8% and 20% of people with diabetes over 45 years of age. Their risk of heart disease is 2–4 times higher than those who do not have diabetes. It is the main cause of disability and death for people with type 2 diabetes in industrialized countries.
IDF fact sheet on diabetes and cardiovascular disease

Amputation
Diabetes is the most common cause of amputation that is not the result of an accident. People with diabetes are 15 to 40 times more likely to require lower–limb amputation compared to the general population.

Source: International Diabetes Federation