Complications of diabetes

Heart disease and stroke

Early cardiovascular disease (that is, disease of the heart and bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. vessels) is the most common cause of complications in diabetes.[1]

Diabetes increases the risk of the arteries becoming 'furred up', called atherosclerosis, which in turn can reduce the bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. supply to the heart. This can cause chest pain on exercise that is known as anginaA central chest pain caused by insufficient oxygen supply to the heart.. It can also increase the risk of complete blockage of the bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. vessels, which may lead to a heart attackThe death of a section of heart muscle caused by an interruption in its blood supply. Also called a myocardial infarction. or a stroke.

Having diabetes increases the risk of heart disease or stroke by up to three times compared with people who do not have diabetes.[2]

Fortunately, though, most of these problems can be prevented or delayed.[3]

It is important to control your bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. pressure, because doing this can reduce the risk of stroke, heart attackThe death of a section of heart muscle caused by an interruption in its blood supply. Also called a myocardial infarction. (myocardial infarctionDeath of an area of heart muscle due to poor blood supply.), and disease of the peripheral bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. vessels (peripheral vascular disease).[2]

While any fall in blood pressure is helpful, some bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. pressure-lowering medications may be of extra benefit - these include angiotensin-converting enzymeA protein that speeds up chemical reactions in the body without being used up itself. inhibitors (ACE inhibitors) and angiotensin 2 receptor antagonists.[2]

Prevention and management

It is important to correct any abnormality in cholesterolA substance present in many tissues and an important constituent of cell membranes although high concentrations of a certain type of cholesterol in the blood are unhealthy. and other lipidOne of a group of compounds that are an important energy source. levels early, as this can help to reduce your risk of heart attackThe death of a section of heart muscle caused by an interruption in its blood supply. Also called a myocardial infarction.. Improving your bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. glucoseA simple sugar that is an important source of energy in the body. levels can help to bring lipidOne of a group of compounds that are an important energy source. levels back to normal too. Certain medications and drinking too much alcohol can also disturb lipidOne of a group of compounds that are an important energy source. levels, as can smoking.[2]

Medicines that help to bring lipidOne of a group of compounds that are an important energy source. levels back to normal and thus reduce vascular problems such as heart attackThe death of a section of heart muscle caused by an interruption in its blood supply. Also called a myocardial infarction. and stroke include statinsA class of drugs that inhibit cholesterol formation in the liver. and fibrates; these may be given alone or together. Your doctor may also recommend low-dose aspirin.[1]

Poor bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. glucoseA simple sugar that is an important source of energy in the body. control and smoking both increase the risk of diabetic retinopathy, which the World Health Organization has estimated is the cause of five per cent of all blindness worldwide

Eye problems

People with diabetes are at risk of a complicationA condition that is linked to, or is a consequence of, another disease or procedure. called diabetic retinopathy that can threaten vision. Prolonged high bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. sugar causes swelling and leakage of the tiny bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. vessels of the retina at the back of the eye, along with blockages in these vessels.[4]

This in turn reduces the oxygen supply to the retina and stimulates the formation of abnormal new bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. vessels, a process called neovascularisation. These new vessels grow out across the retina and are fragile. If they leak, this interferes with vision.

They may also form scar tissueA type of connective tissue that forms after a wound heals. over the retina, putting it under tension and pulling it away from the back of the eyeball. This can lead to a condition called retinal detachment, which requires emergency treatment to prevent sight loss.

Poor bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. glucoseA simple sugar that is an important source of energy in the body. control and smoking both increase the risk of diabetic retinopathy, which the World Health Organization has estimated is the cause of five per cent of all blindness worldwide.[1]

Because type 2 diabetes can go unnoticed for many years, by the time of diagnosisThe process of determining which condition a patient may have., up to a quarter of patients will have some early changes in the retina.[4] This is known as background retinopathy and is not itself sight-threatening.[3] However, it is a warning sign that bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. glucoseA simple sugar that is an important source of energy in the body. levels need to be controlled to prevent more serious changes developing.

People with diabetes are also at higher than average risk of cataract and glaucomaIncreased pressure within the eye (intraocular pressure), which leads to visual loss., other eye conditions that may also threaten sight. Fortunately, treatment in time can prevent vision loss from these conditions. This is why regular screening for the early signs of diabetic eye disease is so important.[4]

Prevention and management

Everyone with diabetes needs regular eye checks, at least annually, to look for early signs of diabetic eye disease. Provided changes are detected early, all of these problems are readily treatable.

For diabetic retinopathy, a test called fluorescein angiographyA technique for assessing the blood vessels in the retina, using a dye to see the vessels more clearly. can help to identify the main cause of retinal damage: small bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. vessel leakage or blockage.[4]

A treatment called retinal photocoagulation is effective in treating problems of the retina, especially if it is given at an early stage, before symptoms develop.[3]

Learn more about diabetic eye disease.

Kidney problems

Like the small bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. vessels of the retina, the small vessels of the kidneys are also more likely to become blocked and leaky in people with diabetes. This results in the kidneys functioning less well. These effects are called 'diabetic nephropathy'.[3]

People with diabetic nephropathy often have a family history of kidney disease or high bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. pressure, suggesting that genes may play a role.  It is also more common in people with diabetes who smoke.

Prevention and management

Prevention of diabetic nephropathy in diabetes is all the more important because this condition is very difficult to manage. However, very close control of bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. glucoseA simple sugar that is an important source of energy in the body. and blood pressure may reduce the risk of kidney damage.[5]

The urine should be tested regularly for small amounts of albuminA type of chemical called a protein, formed in the liver., a type of protein that suggests kidney problems are developing. Such presence in the urine is called microalbuminuriaThe presence of small amounts of albumin, a type of protein, in the urine..[6]

Having diabetic kidney disease influences which medicines can be taken to treat the diabetes itself. For example, people with kidney disease should avoid taking metformin.[3]

Research suggests that the best medicines for the prevention of diabetic nephropathy are a class of drugs called angiotensin-converting enzymeA protein that speeds up chemical reactions in the body without being used up itself. inhibitors, also known as ACE inhibitors. This is a type of bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. pressure-lowering medication.[1]

People with diabetes who have erectile dysfunctionInability to maintain a penile erection for sexual intercourse. are also more likely to have cardiovascular disease

Disease of the nerves

Nervous system problems caused by diabetes are called 'diabetic neuropathy'. This condition may be seen quite early in the course of diabetes, and is relatively common.[3]

Both the sensory nerves that enable sensation and the motorRelating to the part of the nervous system that carries information from the brain and spinal cord to cause activity in a muscle or gland. nerves that control movement may be affected. So too may be the autonomicThe part of the nervous system supplying muscles such as the heart and bowels, known as involuntary muscles. nerves that control automatic functions, such as those of the cardiovascular and gastrointestinal systems.

Diabetic neuropathy may affect groups of nerves or single nerves in isolation.[3]

While problems with the nervous system do not cause any symptoms in most people with diabetes, symptoms can include pain and altered sensation, for example, in the feet or legs. Weakness and wasting of the legs, and occasionally the arms, may also be experienced.

Peripheral neuropathy may also contribute to the formation of ulcers in the feet (see diabetic foot disease, below) and in extreme cases may warrant amputation.[1]

Problems in the nerves of the autonomicThe part of the nervous system supplying muscles such as the heart and bowels, known as involuntary muscles. system can lead to swallowing difficulties, constipation and erectile dysfunctionInability to maintain a penile erection for sexual intercourse..[1,3]

Diabetes is also a common cause of delayed stomach emptying, a condition known as gastroparesis, due to damage to the nerves controlling stomach action. This may cause abdominal pain, nausea and vomiting. It also makes bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. sugar control more difficult because it is difficult to predict the time interval between eating and digestion.

Erectile dysfunction

Erectile dysfunction may be caused by damage to the small nerves and bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. vessels. Smoking increases the risk of this problem. However, it can be treated with medication.[3]

People with diabetes who have erectile dysfunctionInability to maintain a penile erection for sexual intercourse. are also more likely to have cardiovascular disease.[7]

Find out more about erectile dysfunction, including its treatment.

Diabetic foot disease

Foot care is important in diabetes because complications often occur in the feet.[3]

The main underlying causes of foot problems are nerveBundle of fibres that carries information in the form of electrical impulses. damage and reduced oxygen supply due to damaged bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. vessels.[8]

Nerve damage may mean that small abrasions are not noticed due to a lack of sensation. This may lead to the formation of an ulcer. Poor oxygen supply to the tissues of the foot due to bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. vessel disease can also cause ulcers. It is common for foot ulcers to become infected, and this increases the risk of gangreneTissue death owing to very poor blood supply..[3,8]

Common sites of foot ulcers include: [8]

  • The tips of the toes
  • Below the base of the toes.

Problems that may lead to ulcers include: [8]

  • Friction in badly fitting shoes
  • A callusAn area of skin that has become thickened by pressure or friction. that is not treated
  • Nail infections.

The joints may also become deformed due to reduced sensation in the area. This is caused by disease of the bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. vessels and nerves and is called Charcot arthropathyJoint problems caused by poor sensation, which leads to an abnormally wide range of movement..[3]

Prevention and management

Early assessment of the arterial bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. supply and management of ulcers are both important in avoiding the need for amputation, which is almost always avoidable.[8]

Management of foot disease includes:[3]

  • Antibiotics to treat infectionInvasion by organisms that may be harmful, for example bacteria or parasites.
  • Improvement of bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. glucoseA simple sugar that is an important source of energy in the body. control
  • Regular visits to a podiatrist
  • Specially made and orthotic footware.
References: 
  1. Marshall SM, Flyvbjerg A. Prevention and early detection of vascular complications of diabetes. BMJ 2006; 333: 475-80.
  2. Watkins PJ. ABC of diabetes: cardiovascular disease, hypertensionHigh blood pressure., and lipids. BMJ 2003; 326: 874-6.
  3. Boon NA, Colledge NR, Walker BR. Davidson's Principles and Practice of Medicine. Churchill Livingstone Elsevier, 2006; 20th edition.
  4. Watkins PJ. ABC of diabetes: retinopathy. BMJ 2003; 326: 924-6.
  5. Stratton IM, Adler AI, Neil HAW et al. Association of glycaemia with macrovascularRelating to large blood vessels. and microvascularRelating to small blood vessels. complications of type 2 diabetes (UKPDS 35): prospective observational study. BMJ 2000; 321: 405-12.
  6. Freedman BI, Bostrom M, Daeihagh P et al. Genetic factors in diabetic nephropathy. Clin J Am Soc Nephrol 2007; 2: 1306-16.
  7. Billups KL. Sexual dysfunction and cardiovascular disease: integrative concepts and strategies. Am J Cardiol 2005; 96: Suppl 12B: 57M-61M.
  8. Watkins PJ. ABC of diabetes: the diabetic foot. BMJ 2003; 326: 977-9.