Long Term Complications


This page contains summary information about various long term complications of diabetes. For more detailed consideration of this subject you are recommended to explore the whole section on “Long Term Complications“.

“People with diabetes can lead a normal life.” So say the medical profession and the diabetes associations. Yet diabetes is a leading cause of death in most developed countries. What’s normal about living in constant fear of the threat of blindness, kidney failure, heart disease?

What’s covered on this page

What Are ‘Diabetic Complications’?

Why Do These Conditions Develop?

Long Term Effects of Hypoglycaemia


What Are ‘Diabetic Complications’?

As treatment strategies have improved, people with diabetes are living longer and the long term effects of diabetes on the body have become apparent. Not all people with diabetes will go on to develop complications, but most are affected to some degree. Many people with Type 2 diabetes already have some degree of complications when they are diagnosed.

Diabetes takes its toll in the form of damage to numerous body tissues, including the eyes, nerves, kidneys and heart. These ‘complications’ are chiefly the result of damaged blood vessels.


Clinical term

Affected body part 

What does it mean?

Microvascular damage. This is damage to small blood vessels and plays a part in complications of the eyes, nerves and kidneys.
Retinopathy Eyes The small blood vessels at the back of the eye (retina) become damaged. Fluid and other components from blood leak into the eye, blurring vision.

As this condition progresses, new fragile blood vessels start to form (proliferation). These grow forwards and bleed into the clear jelly-like part of the eye through which we see. In addition, fibrous scar tissue may form which shrinks, tearing the retina apart. If left untreated, proliferative retinopathy can result in blindness.

Neuropathy Nerves Nerves allow body cells to communicate with the brain. Blood vessels supply the nerve cells with oxygen and nutrients. When these become damaged, nerves are starved and do not function properly. Electrical messages through the nerves are interfered with, or stopped altogether.

Damage to nerves may lead to any of a number of problems including:

  • loss of sensation in the hands or feet
  • urinary problems such as incontinence
  • sexual problems such as impotence
  • digestive problems
  • dizziness
  • uncontrolled sweating
  • lack of recognition of hypos

Damage to blood vessels and nerves in the feet can lead to ulcers and amputation.

Nephropathy Kidneys The kidneys rid the body of undesirable toxins by passing blood through many tiny filtering units (glomeruli). Damaged small blood vessels can prevent the glomeruli from working properly. In the early stages of kidney disease small amounts of blood protein (albumin) begin to leak through into the urine. This condition is called microalbuminuria (micro-albumin-urea) and is usually the first stage of kidney disease to be detected.

As the condition progresses (this may be over many years), the kidneys lose their ability to filter waste products from the blood, and more protein is leaked out. Sometimes people develop high blood pressure.

If the damage becomes severe then the toxins may build up in the blood to dangerous levels (kidney failure). Then toxins need to be removed from the blood artificially by dialysis. Some patients may go on to have a kidney transplant.

Macrovascular damage or Cardiovascular disease. This is damage to the main blood vessels and is involved with ‘hardening of the arteries’ (atherosclerosis) and heart disease
Atherosclerosis Blood vessels Deposits form on vessel walls, narrowing them. As vessels become clogged up, blood supply is restricted.

A stoppage of blood flow to the heart can cause a heart attack. A stoppage of blood flow to the brain can cause a stroke.

Angina Heart If blood flow to the heart is slowed for a period of time, this may give a person chest pain.
Hypertension. This is high blood pressure and can contribute to both microvascular and macrovascular disease. High blood pressure puts stress on the heart, meaning it has to work harder. It can also cause a fatty tissue (atheroma) to develop on the insides of blood vessels, narrowing and clogging the vessels


Why Do These Conditions Develop?

High blood glucose levels

Recent trials have shown that keeping blood glucose levels as close as possible to normal can prevent, or delay, the development of many of these complications. Therefore it seems reasonable that high blood glucose levels (hyperglycaemia) can cause widespread damage over a period of years – but how? More detailed information on the mechanisms of hyperglycaemic damage can be found in the section on the long term effects of hyperglycaemia.

Other effects of diabetes

Many people with diabetes have different levels of fats or lipids in their bloodstream compared to non-diabetic people. High blood pressure (hypertension) is also more common. People with diabetes also tend to have different levels of blood clotting agents. These factors together are likely to contribute to the development of long term complications.


Not all people with diabetes go on to develop complications in later life. Some people seem to escape them in spite of having blood glucose control which is comparable to that of others who do develop complications. This has led researchers to believe that genes may play a role and studies are underway to investigate this further.

It has also been suggested that high glucose levels in the body may act to turn some genes on or off and this phenomenon may be involved in the development or acceleration of diabetic complications.

Long Term Effects of Hypoglycaemia

So far, the emphasis has been on the importance of keeping blood glucose levels down. However, particularly for people taking insulin, this increases the chances of hypoglycaemia. Apart from the immediate problems, hypoglycaemia can actually cause damage in the long term.

Loss of hypo awareness

As a rule, warning signs of a hypo are experienced as the blood glucose level starts to drop. These might include sweating, shaking or hunger. It has been noted in many cases that gradually, over a period of years, these warning signs start to come on later. This means that the blood glucose may fall very low before the individual becomes aware of the situation and realises that he/she needs to take glucose. People with hypoglycaemia unawareness may suffer from repeated severe hypos, and may be at risk of fitting or unconsciousness.

Changes in brain function

Recently another long term problem associated with hypoglycaemia has come to light. Some people who have had Type 1 diabetes for many years seem to have suffered from damage to the frontal lobes in the brain and this is thought to be related to frequent or severe episodes of hypoglycaemia over time. As a result, these people appear to suffer from lack of concentration, poor judgement, a loss of reasoning and a reduced ability to interact with other people.

Many such people also have signs of the more well-defined complications outlined above; it is possible that nerve damage in particular, might add to the problem.

Recurrent severe hypoglycaemia in young children has also been reported to affect learning and development to some extent in certain individuals. However, on a positive note, a study carried out in Australia suggested that “seizures/coma at a young age does not necessarily result in gross cognitive or behavioral impairment.”

Explore this section Introducing Diabetes

What is Diabetes?  |  Causes of Diabetes  |  Long Term Complications  |  Managing Diabetes