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Diabetes mellitus is a condition in which the level of glucose (sugar) in  blood becomes too high because the body cannot use it properly. This results either from an inability to produce insulin or because the  body has become resistant to the insulin produced. About 2.8 million people in the United Kingdom (4.45% of the population) are known to have diabetes and a further ¾ million may have the condition and not know it. Insulin is a hormone, produced by  the pancreas, which controls the movement of glucose into most of the body's cells and maintains blood glucose levels within a narrow concentration range. Most tissues in the body rely on glucose for energy production, and all but a few are entirely reliant on insulin to deliver this essential fuel. Diabetes disrupts the normal balance between insulin and glucose. Insulin allows glucose into the cells.

If there is insufficient or ineffective insulin, glucose levels remain high in the bloodstream and the body's cells "starve”.

This can cause both short term and long term problems depending on the severity of the imbalance. In the short term it can upset the body's electrolyte balance, causing dehydration as high blood glucose levels increase the amount of urine produced. If unchecked, this can eventually lead to loss of consciousness, kidney failure and death. In the longer term, sustained high glucose levels can damage blood vessels, nerves, and organs throughout the body, contributing to other problems such as high blood pressure, heart disease, kidney failure and loss of vision in addition to diabetes.

Diabetes types
There are two types of diabetes: Type 1 (which used to be called insulin dependent diabetes or juvenile onset diabetes) and Type 2 (which used to known as non-insulin dependent diabetes or adult onset diabetes). In addition, Gestational Diabetes is a term used to describe diabetes which is recognised for the first time during pregnancy. Pancreatic disease or damage can also cause diabetes if the insulin producing beta cells are destroyed.

Risk factors include:

  • Weight excess / obesity
  • Lack of exercise
  • A family history of diabetes
  • Any abnormality of glucose tolerance – the oral glucose tolerance test (OGTT) may identify individuals whose ability to handle a high glucose meal is not normal but is not sufficiently abnormal to identify them as Diabetic
  • Ethnic groups - more common in Asian and African-Caribbean communities
  • Gestational diabetes during pregnancy or baby weighing more than 9 pounds
  • High blood pressure
  • High triglycerides, high cholesterol, low HDL

Because the population of the western world is becoming more obese and not getting enough regular exercise, the number of those developing type 2 diabetes is rising and, of particular concern is its development in young people.

Gestational diabetes is usually a temporary type of hyperglycaemia (high blood glucose concentration) seen in some pregnant women, usually during the second or third trimester. The cause is unknown, but it is thought that some hormones from the placenta increase insulin resistance in the mother causing elevated blood glucose levels. In the UK, gestational diabetes is usually diagnosed by an oral glucose tolerance test carried out, either because high glucose concentrations have been found in the urine or blood or because the women is known to be at risk for the condition. Testing is usually performed between the 24th and 28th week of pregnancy. Gestational diabetes also raises the risk of eventually developing type 2 diabetes, for both the mother and the baby.

Impaired fasting glycaemia or impaired glucose tolerance (sometimes referred to as "pre-diabetes") are conditions which can only be detected by use of the oral glucose tolerance test and are characterised by glucose levels that are higher than normal, but not high enough to be diagnostic of diabetes. Usually these individuals do not have any symptoms but if nothing is done to lower their glucose levels, they are at great risk of developing diabetes in the future. Recognising these conditions is important as recent evidence shows that progression to diabetes can be markedly reduced by simple measures such as weight loss and increased exercise.

Signs and Symptoms
Symptoms of type 1 and type 2 diabetes with hyperglycaemia may include any of:

  • Increased thirst
  • Passing increasing amounts of urine
  • Increased appetite (with type 1 weight loss is also seen)
  • Tiredness
  • Feeling sick
  • Vomiting
  • Stomach pain (especially in children)
  • Blurred vision
  • Slow-healing infections
  • Numbness, tingling, and pain in the feet
  • Erectile dysfunction in men
  • Absence of menstruation in women
  • Rapid breathing (acute)
  • Decreased consciousness, coma (acute)

Symptoms of impending hypoglycaemia:
Temporary hypoglycaemia in the diabetic patient may be caused by the accidental injection of too much insulin, not eating enough or waiting too long to eat, exercising strenuously, or by the swings in glucose levels seen in patients with diabetes which is difficult to control (often referred to as 'brittle diabetes'). Hypoglycaemia needs to be treated because, if it is severe, it can rapidly progress to unconsciousness. True hypoglycaemia occurs when the blood sugar is below 2.5 mmol/L, though symptoms may develop earlier, especially if the blood sugar falls rapidly, and include:

  • Sensation of hunger
  • Headache
  • Anxiety
  • Sweating
  • Confusion
  • Trembling
  • Weakness
  • Double vision
  • Convulsions (severe)

Common Tests
Diabetes is diagnosed by measurement of glucose in blood (or more correctly in plasma which is the fluid left behind when cells have been removed from blood) in accordance with the criteria of the World Health Organisation.

Either random or fasting measurements or the measurements made during an oral glucose tolerance test (OGTT) may be used. In an individual with typical symptoms, diabetes is diagnosed by finding either a random plasma glucose concentration greater than 11.0 mmol/L or a fasting plasma glucose concentration greater than 7.0 mmol/L or a plasma glucose concentration greater than 11.0 mmol/L two hours after taking 75g of anhydrous glucose in an OGTT.

HbA1c (also called haemoglobin A1c or glycohaemoglobin) evaluates the average amount of glucose in the blood over the last 2 to 3 months and has been recommended more recently as another test to screen for diabetes.

Sometimes random urines are tested for glucose, protein, and ketones during a routine clinical examination using a 'dipstick test'. If glucose and/or protein or ketones is present on the dipped indicator strip then further investigations are necessary. This screening tool is not sensitive enough for monitoring patients who have been diagnosed as diabetic.

Several laboratory tests may be used to monitor diabetes on a regular basis.

To monitor glucose control:
Glucose, Haemoglobin A1c (HbA1c)

To monitor kidney function:
Creatinine, Creatinine Clearance, Microalbuminuria  (A test which detects very small quantities of albumin in the urine and can indicate early kidney damage.  It is measured as the Albumin Creatinine ratio (ACR) or Albumin Excretion rate)

To monitor lipids:
Triglycerides, cholesterol, HDL cholesterol, LDL cholesterol

While there is no way to prevent type 1 diabetes, the risk of having type 2 diabetes can be greatly decreased by losing excess weight, exercising and by eating a healthy diet with limited fat intake. By identifying pre-diabetic conditions and making the necessary lifestyle changes to lower glucose levels to normal levels you may be able to prevent type 2 diabetes or delay its onset by several years.  Normalising blood glucose can also minimise or prevent vascular and kidney damage.

There is currently no cure for diabetes. The goals of diabetes treatment are to keep glucose levels close to normal and to treat any progressive vascular disease or organ damage that arises.

Ongoing treatment involves daily glucose monitoring and control, eating a healthy planned diet, and exercising regularly.

It is important to work closely with your doctor or diabetes nurse and have regular checks that can include monitoring tests such as microalbuminuria, haemoglobin HbA1c, lipids and tests of kidney function in addition to blood pressure, eye and foot tests. Immediate attention is required for complications such as:

  • Wound infections, especially on the feet. Aggressive and specialised measures are often necessary
  • Vision problems, diabetic retinopathy can lead to eye damage, a detached retina, and to blindness.
  • Urinary tract infections which may be frequent and resistant to antibiotic treatment