Complication risks

This section highlights areas where complications may develop, the reasons for this and the possible outcomes. It is not an exhaustive list of potential areas of complications, but should help you in making clinical decisions and understanding the importance of seeking expert help.

The information is arranged alphabetically by topic:

Blood/glucose control

The aim is to achieve the best possible metabolic control from as early as possible. There is no HbA1c threshold below which diabetes complications will not develop or progress, short of normal glycaemia.

The Diabetes Control and Complications Trial (DCCT), which involved people with type 1 diabetes, showed a non-linear relationship between the risk of complications and HbA1c values. These relationships describe a constant relative risk gradient in which proportional reductions in HbA1c are accompanied by proportional reductions in the risk of complications.

Although the magnitude of the absolute risk reduction declines with continuing proportional reductions in HbA1c, there are still meaningful further reductions in risk, as the HbA1c is reduced towards the normal range.

The UK Prospective Diabetes Study (UKPDS) of patients with type 2 diabetes showed that better blood glucose control reduces the risk of:

  • major diabetic eye disease by a quarter
  • early kidney damage by a third.

The ACCORD study which was undertaken in the USA and Canada between 2001 and 2009 was designed to determine “if a strategy of intensive lowering of blood sugar levels, intensive lowering of blood pressure, or treatment of blood lipids with a fibrate drug plus a statin drug, can reduce the risk of major CVD events in patients with type 2 diabetes who are at especially high risk of CVD”.  One of the clinical trials involved was stopped early for safety reasons. The interventions did not reduce the rates of cardiovascular outcomes as hypothesised. For further details see the pages on the USA National Heart, Lung and Blood Institute about the Action to Control Cardiovascular Risk in Diabetes (ACCORD) Trial and the ACCORD website.

In the ACCORD study, one of the clinical trials was stopped early as it appeared that the intensive lowering of blood glucose levels slightly increased the cardiovascular death rate, but in a larger trial ADVANCE did not find increased mortality. There are links to information and discussion about these trials and their implications in the Diabetes UK Diabetes Bulletin 18 June 2008.

Further analysis of the ACCORD study has found that “intensive blood glucose control did not reduce composite advanced microvascular outcomes (renal complications, eye complications or peripheral neuropathy) compared with standard blood glucose control” see National Prescribing Centre’s MeRec Monthly issue no 33 December 2010.

Recommendations about HbA1c levels and frequency of testing are made by NICE in the guideline on Type 2 diabetes and the management of type 2 diabetes. 

See also the section on blood glucose monitoring in the 'Treatment and lifestyle' area of this resource.

Contraception/sexual health

If an unplanned pregnancy in a woman with diabetes occurs in the setting of poor diabetes control, the risk of congenital malformations, foetal death and macrosomia is greatly increased.

Young women may notice higher blood glucose levels the days before their menstruation and may need adjustments to the insulin dosage during this time.

Poorly controlled diabetes can lead to irregular or missed periods.

See also the sections on pregnancy and sexual health in the 'Good practice' area of this resource for further information.

Eyes (risk of retinopathy)

Early retinopathy is asymptomatic but may be detected by screening the retina for changes. Early or background retinopathy is non-vision threatening - it may remain stable for years, may sometimes regress, or may progress to more severe retinopathy.

For every 10 per cent improvement in HbA1c (e.g. 8.0 per cent to 7.2 per cent), the risk of developing retinopathy decreases by 43 per cent (DCCT study).

The National Screening Programme for Diabetic Retinopathy in England recommends that all people with diabetes aged 12 years and over should have eye screening - see Eye screening for people with diabetes - the facts. 

The International Society for Pediatric and Adolescent Diabetes (ISPAD) underlines the importance of screening for the early signs of retinopathy in adolescence because of higher risk of progression compared with adult patients (ISPAD 2009).

See also the section on Screening for retinopathy in the 'Good practice' area of this resource.

Feet

Risk of foot problems are often associated with neuropathy, a lack of sensation to alert the person of a trauma to the foot or problems with identifying when the foot hits the floor. This can combine with vascular complications, poor blood supply to the limb prolonging the bodies response to infection and increasing risk of skin breakdown, often resulting in ulcers. Early interventions for foot problems can reduce amputations by two thirds (Audit Commission 2000).

Important consideration are:

  • prompt treatment of any infections or minor trauma, avoid trauma where possible
  • ingrown toenails
  • tinea pedis (athletes foot)
  • biomedical problems (ill-fitting footwear)
  • callus formation (look for limited joint mobility)
  • charcot joints.

See also the section on Older people and footcare in the 'Good practice' area of this resource.

Injection sites

Injection sites used are:

  • thighs
  • upper arms
  • stomach
  • buttocks.

Risk of lipoatrophy - a loss of fat under the skin producing small dents (uncommon with the use of highly purified human insulins) and risk of lipohypertrophy -  a build up of fat under the skin resulting in lumps are caused by repeated injection into the same site.

It is important to note that: 

  • insulin absorption from these areas is more erratic and unpredictable
  • risk is reduced through better rotation of injection sites. For example using one site for a week and then rotating to another site and so on
  • a n area affected by lipohypertrophy should not be used for injection until it has become soft which may take weeks or months depending upon severity.  

The fact that the absorption rate of insulin varies from one injection site to another also needs to be considered and this is further altered by exercise of the muscles underlying the site. For example if insulin is injected into the thigh just before vigorous exercise such as running or cycling this will result in insulin being absorbed more quickly than if the injection had been made into the stomach before the same exercise.

The RCN provides guidance on injection technique in Starting insulin treatment in adults with Type 2 diabetes (PDF 255.85KB).  [see how to access PDF files]

Kidneys (risk of nephropathy)

People with diabetes run the risk of harming their kidneys as a result of the duration of their condition and the damage done to their kidneys by raised blood glucose.

A booklet from NHS Diabetes and published in March 2011 provides key information about the impact of kidney disease in diabetes, in particular what puts people at risk of developing kidney disease and what can be done about it - see Diabetes with kidney disease: key facts (PDF 691.46KB).

Information about recommendations for monitoring and investigating kidney damage in type 2 diabetes are given in the NICE pathway for diabetes - see the section on identifying and managing kidney damage.

Diabetes UK provide an overview of risks for kidney disease, symptoms, tests that are carried out and some possible treatments at kidneys (nephropathy).

See also the Renal section in the 'Good practice' area of this resource.

Liver

Alcohol inhibits gluconeogenesis and may result in delayed hypoglycaemia, from the decreased concentrations of cortisone and growth hormone following alcohol consumption. Binge drinking may result in vomiting, aspiration and diabetic ketoacidosis (DKA).

DKA, a life-threatening acute complication, results from severe insulin deficiency and is characterised by high blood glucose, high levels of ketones and electrolyte imbalance. 

See also the section on Alcohol in the 'Treatment and lifestyle' area of this resource.

Microvascular/macrovascular complications

Complications of diabetes are often described as:

Microvascular: those  arising from damage to the smaller blood vessels such as retinopathy, renal disease and neuropathy.

Macrovascular: those arising from damage to the larger blood vessels such as myocardial infarction, stroke, and peripheral arterial disease (PAD).

Considerations are:

  • large vessel disease (macrovascular) does not often manifest in children/young people but has its beginnings in early childhood
  • microvascular disease is accelerated by poor blood glucose control, raised blood pressure and smoking. Macrovascular disease has the additional components of central trunk obesity or Syndrome X
  • risk factors for the complications of diabetes include younger age at onset of the disease process, longer duration of diabetes, poor glycaemic control, family history of macro and micro vascular disease, higher blood pressure, smoking, abnormal lipid levels
  • in addition to maintaining good glycaemic control it is important to encourage healthy exercise in this group of individuals.

Effects of smoking

Smoking should be discouraged as in addition to raising the cardiovascular risk factors, Hanas (1998) has shown nicotine from smoking affects the blood glucose level by contracting the blood vessels, resulting in slower absorption of insulin from the injection sites. This allows blood glucose levels to rise and then to fall dramatically as the insulin is absorbed. This see-sawing of blood glucose levels has been implicated in the progression and instance of the long-term complications of diabetes.

Nerves (risk of neuropathy)

Clinical neuropathy is rare in children/young people with satisfactory glycaemic control, however it is a serious and painful problem for adults who have had diabetes for several years.

In the presence of poor diabetic control, both adults and young people should be questioned and examined in relation to:

  • symptoms of numbness, pain, cramps and parathesia
  • skin sensation, vibration sense and light touch
  • ankle reflexes.

(ISPAD 2009).

Specific guidance on the pharmacological management of neuopathic pain is available from the National Institute for Health and Clinical Excellence (2010) .

Skin

Hyperglycaemia causes fluid loss and dehydration resulting in dry and itchy skin.

Bacterial infections occur five to 10 times more frequently in people with diabetes. If blood glucose levels are high, white blood cells work less efficiently and the risk of infection is increased (Hanas 1998).

Features of fungal infection are:

  • genital itching
  • the fungus thrives better when blood glucose levels are high or when being treated with antibiotics, that disturb the normal genital flora (Hanas 1998)
  • fungal infections in children can appear as cracks in the corner of the mouth or lesions in the cuticle or between fingers.

Skin lesions are called necrobiosis lipoidica diabeticorum. They are progressive dry necrosis of skin and subcutaneous tissue in areas from coin to palm size. They start as an insensitive bluish-red efflorescence which rapidly grows and atrophies from the center, leaving a reddish-brown area of atrophic skin, and sometimes ulcers. The cause is unknown but some data indicates an autoimmune origin (Hanas 1998).

For further information and support, go to: Diabetes UK: Skin necrobiosis.

Stomach

Emptying of the stomach is affected by the blood glucose concentration, this is slower when the blood glucose level is high and quicker when blood glucose level is low.

Poor motility and gastro paresis may occur due to damage of the autonomic nervous system after many years of having diabetes.

Other symptoms include an early feeling of satiety and a feeling of stomach distension.

Symptoms may be reduced through a decreased HbA1c.

If the rate of absorption of digested carbohydrates and glucose is altered through these complications a greater risk of poor post prandial blood glucose control is possible.

Some people with delayed gastric emptying are helped to avoid post prandial hypoglycaemia by using one of the fast acting insulin analogues after eating.

Teeth

The same importance is attached to dental hygiene for people with diabetes as for the rest of the population and dental checks are an important part of general health care.

References

Full details of the bracketed citations in the text above and, in many cases, links to the actual documents are available in the reference list within this resource. Go to: Reference list.

For further information and guidance on complications see Resources.