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Effective management of hypoglycaemia

Hypoglycaemia is an acute complication of diabetes, caused by low blood glucose levels. It can occur in people with diabetes who are being treated with either insulin or sulphonylureas. Karen Jones provides a guide to symptoms, causes and treatment

Karen Jones
Locality Lead
Diabetes Specialist Nurse
Northumbria Healthcare Trust

Hypoglycaemia – hypo- (low) gly- (glucose) -aemia (of the blood) – is an acute complication of diabetes. It occurs when the blood glucose level falls below 3.5 mmol/l. There are two types of hypoglycaemia:

  • Mild – the patient is able to treat themselves.
  • Severe – the patient needs assistance from someone else.1

There are many symptoms of hypoglycaemia and patients who are on diabetes treatment, which can cause the condition, need to be made aware of these. If symptoms occur, the patient can then monitor their blood glucose level; if it falls below 4 mmol/l they are advised to commence treatment (Diabetes UK has a leaflet for patients about this).2 Treatment is usually advised when levels fall below 4 mmol/l to try to prevent its progression, even though hypoglycaemia does not occur until the blood glucose level is below 3.5 mmol/l.

The symptoms of hypoglycaemia (see Box 1) occur at different blood glucose levels. Some symptoms occur at blood levels of 3.5–2.8 and these are known as adrenergic symptoms caused by activation of the sympathetic nervous system. Other symptoms occur at blood glucose levels below 2.8 mmol/l due to insufficient glucose entering the brain; these are known as neuroglycopenic symptoms. The brain cannot store glucose, so if it is unable to uptake sufficient glucose it cannot function properly – this occurs when the blood glucose level falls below 2.8 mmol/l. It is important that a person recognises the early symptoms and treats the hypoglycaemia quickly to prevent neuroglycopenic symptoms from occurring. If neuroglycopenic symptoms occur, the person becomes unable to treat the hypoglycaemia themselves and severe hypoglycaemia occurs.

[[Box 1 hypog]]

If a person experiences hypoglycaemia regularly, the brain receptors reset to accept this as normal, do not react and do not produce the adrenergic response to hypoglycaemia. If no response occurs, neither do the early warning signs, and this is known as hypo-unawareness.3 This puts the person in danger as they will not be able to treat their own hypoglycaemia.

It is important to discuss hypoglycaemia and how often it is occurring with patients on a regular basis to promote awareness of the condition. It is vital to consider the language you use when talking to a patient about this. If you ask, "How many times a week does your blood glucose level fall below 4 mmol/l?", you may get a very different answer than you would to the question, "How many times a week do you experience hypoglycaemia?" This is because, often, if you ask a person about hypoglycaemia, they think you are talking about becoming unconscious. Typically, they will answer "never", when their blood levels may be dropping below 4 mmol/l five to six times a week, but they are managing to treat it themselves and do not class it as important or hypoglycaemic.

Patients should be made aware that their hypoglycaemic symptoms can change over time; that there can be different symptoms each time, and that it is important to monitor their blood glucose levels if any symptoms occur. The treatment for hypoglycaemia is glucose. For mild hypoglycaemia (that can be treated by the patient themselves), the treatment is 10–15 g carbohydrate (see Box 2). It is important not to use chocolate, sugary tea or milk with added glucose as these contain a lot of fat, which slows down the absorption of the glucose.

[[Box 2 hyperg]]

The patient should choose a treatment that they like to use. Dextrose tablets are very chalky and some people find them difficult to eat; if this is the case, the patient will probably not manage to eat five for treatment and may find a drink more palatable. People who like jelly babies may be tempted to eat them as a snack rather than saving them as hypoglycaemia treatment.Usually, the person will also have some slower-acting carbohydrate, such as a sandwich, a bowl of cereal or plain biscuits after the glucose to keep their blood glucose level above 4 mmol/l until their next meal.

People on insulin and sulphonylureas should be advised to carry one of these forms of glucose with them at all times so that they can treat a hypoglycaemic episode whenever it occurs. When I am discussing hypoglycaemia with patients I usually ask them to show me the treatment they are carrying. Very often, people are not carrying any treatment and this is a good way of discussing and explaining to the person why it is important to do so. Some people will dig around in the bottom of their bag to find a very old, unclean packet of dextrose tablets, which indicates that they are probably not experiencing hypoglycaemia regularly.

In cases of severe hypoglycaemia where the person is conscious but unable to eat/drink, and thus not being very co-operative, GlucoGel® (on prescription) can be used. This comes in a tube, which should be inserted in the mouth into the buscal cavity in front of the teeth. If the person is unconscious, a glucagon injection can be used. This intramuscular injection comes in a box and has to be mixed with a solution before use. It should be administered into the outer thigh muscle. A relative or friend can be taught how to use this.

If glucagon is used, it is important that the person administering it is aware that it will take up to 10 minutes to work. It can be very frightening for a relative or friend to administer an injection, and if they do not know how long it takes to work they may think it has not had any effect.

Causes of hypoglycaemia
There are several causes of hypoglycaemia (see Box 3). Once treated it is important that the patient thinks about what caused the episode. If they did not eat as much carbohydrate as normal, or skipped a meal, this is easily preventable. If they accidentally took too much insulin/sulphonylurea, again, this is easily preventable. If the person has consciously decided to reduce their portion sizes to lose weight, their medication doses may need to be reduced to accommodate this. A person who is trying to lose weight would find it very frustrating if they regularly had to eat to treat their hypoglycaemia.

[[Box 3 hyperg]]

If exercise was the cause, the person needs to consider whether this is going to be a regular occurrence. If so, they may need to consider reducing their medication or eating carbohydrate before taking exercise. The option they choose depends on whether they are overweight and trying to lose weight, and the form of exercise they are undertaking. It may be worth discussing this with their nurse or doctor. It is important to discuss the effect of exercise on blood glucose levels with people with diabetes in a positive way so as not to put them off exercising completely but ensure that they are aware of a need to manage their medication before exercise. Gary Mabbott (who has type 1 diabetes) and Steve Redgrave (who has type 2 diabetes) are good examples of diabetes not preventing success in sport.

If a person wants to undertake regular intensive exercise, they can be referred to an excellent website – – which has information about all forms of exercise. It is just as important for people who exercise infrequently to consider reducing their medication or eating carbohydrate before exercise. There are many activities that people do not consider to be exercise, which will also lower their blood glucose levels. Spring-cleaning the house is vigorous activity, and walking around a large shopping complex all day may be a big increase in activity for some. It is important to talk about activity levels as well as exercise for this reason.

Alcohol and drugs
Alcohol lowers blood glucose levels, often several hours after it has been ingested. People on insulin often need to reduce their background insulin overnight if they drink more than a couple of units of alcohol. The effects of alcohol on behaviour can be very similar to symptoms of hypoglycaemia (slurred speech, altered behaviour and speech difficulties) and if a person has been drinking alcohol they may be thought to be drunk when in fact they are hypoglycaemic. Therefore, it is important if a person is drinking alcohol that someone with them knows the signs of hypoglycaemia and how to treat them and the person should carry identification stating that they have diabetes.

I know two men in their 20s who were both arrested for being drunk and disorderly. One had ID in their wallet which was found at the police station and was treated with a fizzy drink, recovered and was sent home. The other had no ID, was put into a cell and was later found unconscious and had to be admitted to hospital.

Cannabis lowers blood glucose levels and should be discussed with patients. People report feeling hungry ("the munchies") when smoking cannabis and this is probably due to the lowering of blood glucose levels. If a person is going to smoke they may need to adjust their medication/eat more carbohydrate to compensate for this effect.

Consequences of hypoglycaemia
The effects of hypoglycaemia can have huge consequences on a person's life. If a person becomes aggressive when hypoglycaemic this can be frightening for other people around them and in extreme circumstances could cause the person to become violent.4,5

If a person has hypoglycaemia unawareness, they must not drive a car, which could have implications for their job. People can think that a person is hypoglycaemic when in fact they are just tired or angry – this can cause resentment if in the middle of an argument their partner insists the person tests their blood glucose level to determine whether they are hypoglycaemic. Often, other people recognise the symptoms before the person with diabetes does, so friends and relatives need to handle how they discuss this with the person to try and prevent resentment from occurring.

It is important that other people know the symptoms and how to treat hypoglycaemia so that they can assist if necessary. This means that the person should inform family, friends and work colleagues. Some people are concerned about informing work colleagues in case they are treated differently or even passed over for promotions or overseas trips because of it. Telling new friends or partners can also be anxiety provoking – when do you tell a new partner that you have diabetes and what to do if you become hypoglycaemic?

Some people try to prevent hypoglycaemia by running their blood glucose levels deliberately high, but this increases their risk of chronic complications of diabetes and these people require counselling to prevent this behaviour.

Hypoglycaemia is a common, acute complication of diabetes. To reduce their risk, the patient has to assess every situation on at least a daily basis, for example, how much carbohydrate to eat, how much medication to take, what activity they are planning to undertake and whether they are going to drink alcohol. This does take the spontaneity out of life; however, it is vital to make these considerations to prevent hypoglycaemia occurring regularly.

1. Frier BM. How hypoglycaemia can affect the life of a person with diabetes. Diabetes/Metabolism Research and Reviews 2008;24(2):87–92.
2. Diabetes UK. Hypoglycaemia information sheet. London: Diabetes UK. Available from:
3. Saunders R. Without warning. Balance 2006:28–31.
4. Saunders R. Postcards from the edge. Balance 2006:33–6.
5. Marks V. Hypoglycaemia: accidents, violence and murder. Part 1. Practical Diabetes International 2005;22(8):303–6.