Understanding Diabetes

Updated 29th November 2017


What is it?

Diabetes Mellitus is a medical condition caused by an inability to use sugars due to the body producing ineffective insulin, an ineffective amount or complete lack of insulin in the body.   The effects can be life threatening.


Normal Physiology

Every cell in the human body needs sugars (as well as oxygen) as their source of energy.  The digestive system breaks down complex carbohydrates (long-chain molecules which are too large pass into cells) such as cellulose into simple (small-chain) carbohydrates such as glucose.

Cellulose to glucose 750.png

Glucose enters the blood stream where it is transported around the body to provide energy to cells, however, insulin is needed to combine with the glucose to enable it to pass into - and be utilised by - the cell.

Insulin is a hormone produced by endocrine glands on the pancreas; in a healthy person the body is able to regulate the amount of insulin produced, proportionate to the amount of glucose in the blood. 

Providing the cells have metabolised enough glucose, insulin also acts on the liver to stimulate enzymes which convert excess glucose to glycogen - a long-chain carbohydrate which can be stored for later use.

Given that all cells use glucose as energy, and all cells are constantly using this energy, blood glucose levels will always fall once the cells (and liver) have been 'topped up'.

When blood glucose levels begin to fall, the endochrine glands on the pancreas release another hormone, glucagon, which acts as the counter to insulin and breaks the stored glycogen back into glucose which can then be metabolised by cells.

These automatic responses to blood glucose levels (metabolising, storing, releasing and excreting)  maintains an optimum blood glucose level between 4 and 7 mmol/l ( or 80-120mg/dl in the US ).


Diabetes Mellitus

A casualty with diabetes is either not producing enough insulin or their insulin is not effective - either way glucose circulating in their blood is not able to be metabolised by cells and can accumulate to dangerously high levels - hyperglycaemia.

If a casualty's blood sugar levels drop they do not have the ability to use stored energy in the liver - hypoglycaemia.


Types of Diabetes

Type 1 

  • Patients do not produce insulin; they require daily injections of synthesised insulin to metabolise glucose and control blood glucose levels.  Also known as Insulin Dependent Diabetes Mellitus (IDDM).
  • Type 1 patients are more likely to have metabolic problems, organ damage or nerve disorders.  
  • This type of diabetes was previously known as Early Onset Diabetes as it typically develops during childhood but can develop later in life.

Type 2

  • Patients produce inadequate amounts of insulin or their insulin is ineffective.
  • This condition usually appears later in life.
  • Many patients can be treated with diet, exercise and other non-insulin medications which stimulate the pancreas to produce more insulin. 
  • Type 2 diabetes was previously known as Non-Insulin Dependant Diabetes Mellitus (NIDDM) although this is not always true as some patients may also require supplemental insulin.


What are the Triggers?

Regardless of the type of Diabetes the casualty suffers from, the casualty is in danger of either having too much blood glucose (Hyperglycaemia) or too little (hypoglycaemia).



Without effective insulin or sufficient quantities, glucose builds up in the blood, unable to be metabolised by the cells which need it.

Without usable glucose, the body begins to metabolise other sources of energy - the most abundant being fat.  When fat is burned as an immediate fuel supply the byproducts are fatty acids and ketones, some of which are difficult for the body to excrete. 


You may have heard of ketones in regard to low-carb diets which force the body to burn fat as an immediate source of energy.  Some ketones (acetoacetate and ß-hydroxybutyrate) are used for energy; the heart muscle and kidneys, for example, prefer ketones to glucose.  Most cells, including the brain cells, are able to use ketones for at least part of their energy.  Acetone, however, is a ketone which is not used and so is excreted, giving a characteristic sweet smell on the person's breath or sweat.

An accumulation of ketones reduces the pH levels of the blood (acidosis) leading to Diabetic Ketoacidosis.

Ketoacidosis is a medical emergency; the signs and symptoms include a reduced level of consciousness, weakness, nausea, vomiting, abdominal pain, a weak and rapid pulse, and a distinctive deep and rapid breathing.

As the acidity increases, individual cells will cease to function.

If the casualty is not given correct fluids and insulin to reverse fat metabolism, ketoacidosis will lead to unconsciousness and death.

Ketoacidosis is more common in Type 1 diabetes because of the body's inability to produce any insulin.

Once the blood glucose level reach around 11.1mmol/l (or 200mg/dl US) the body attempts to excrete excess glucose through the urinary system, placing strain on the kidneys and requiring large amounts of water.



In some situations, the diabetic casualty will have too low blood sugar.  A hypoglycaemic episode can occur much quicker than a hyperglycaemic event which typically can take hours to develop.  As the brain is starved of vital glucose, unconsciousness follows, then death.

The triggers to either hyper- or hypglycaemia very much depend on the casualty's history:





Too much food

Not enough food


Too little activity for the food they have consumed or medication they have taken

Too much activity for the food they have consumed or the medication they have taken


Too little insulin

Too much insulin


What are the Symptoms?

In an unconscious casualty, a casualty who is not conversant or where there is no history, it can be difficult to work out the situation from the four sources above.

While the signs and symptoms for both conditions are very similar, there are some important differences.

Signs & Symptoms




Missed or insufficient medication

Excessive food or sugar consumption

Missed meals

High levels of activity

Too much insulin







Excessive urination

Symptoms of dehydration





Reduced level of response




Rapid and deep
Possible sweet smell

Normal to rapid


Rapid, weak pulse

Warm, dry skin

Rapid, weak pulse

Cool, clammy skin


Is it Hyper or Hypoglycaemia?

One of the challenges in managing a casualty with diabetes is working out what is wrong with them; is their blood sugar level too high or too low?

  1. Signs & Symptoms
    The signs and symptoms of both hyper- and hypoglycaemia are similar; noticeably a reduced level of consciousness, weakness and a rapid pulse with only subtle differences elsewhere meaning one needs a very good memory or to be working regularly with diabetic casualties to become adept at quickly differentiating between the two.   Other factors will, however, guide your judgement...  
  2. History
    Begin simply by asking the casualty what happened (or witnesses if the casualty is not conversant).Have they eaten recently, if so what?  Have they been particularly active or missed a meal?   A simple process of deduction will almost certainly reveal a correct diagnoses.
  3. Blood Glucose monitoring
    Casualties with known diabetes will measure their blood glucose levels several times a day using a blood glucose meter.  The blood glucose meter uses a sample of blood and measures the levels of glucose in millimoles per litre (mmol/l).  In the US it is measured in milligrams per decalitre (mg/dl).  In a normal state, everyone's blood glucose levels should be between 4 and 7 mmol/l or 80-120 mg/dl.  A conscious and compliant casualty may be able to test themselves if you are able to bring them their measuring kit.
  4. Likelihood
    In reality, hypoglycaemia is far more common that hyperglycaemia. Everyone burns energy constantly so everyone is potentially susceptible to hypoglycaemia. Hypoglycaemia can occur very quickly.  Hyperglycaemia can take several hours to develop and as diabetics typically monitor their glucose levels several times a day, they are likely to catch glucose levels rising and medicate appropriately.  


What is the Treatment?


There is no prehospital care for the hyperglycaemic casualty, arrange immediate transfer to hospital


Hypoglycaemia (1)

1.  If the casualty is unconscious or unable to swallow:

  • Arrange immediate transfer to hospital
  • Do not administer anything by mouth
  • Monitor the casualty throughout

2.  If the casualty is conscious, orientated and able to swallow

  • Administer 15-20 grams of fast acting carbohydrates
    • 5-7 Dextrosol® tablets (or 4-5 Glucotabs®)
    • 170-220ml of original Lucozade®
    • 150-200ml pure fruit juice e.g. orange
    • 3-4 heaped teaspoons of sugar dissolved in water.
    • 1 tube of energy gel
  • Reassess blood glucose after 10 minutes.

3.  If blood glucose has not risen to at least 5.0 mmol/l, repeat treatment up to three times.

4.  If blood glucose remains less than 4.0mmol/L after 30-45 minutes or 3 cycles,contact a doctor.

5.  Once blood glucose is above 4.0mmol/L and the patient has recovered, give a long acting carbohydrate of the patient’s choice, e.g.

  • Two biscuits
  • One slice of bread/toast
  • 200-300ml glass of milk (not soya)
  • Normal meal if due (must contain carbohydrate).


First Aid Kits

You don't have to be diabetic to become hypoglycaemic - hypoglycaemia should be the first possibility to be checked for anyone with an altered mental status.   If you are unsure of the condition - assume it to be hypoglycaemia and give sugar;  The hypoglycaemic casualty will recover rapidly but the amount of sugar given will have a negligible effect on the hyperglycaemic casualty (2). 

So should I have chocolate in my First Aid kit?

No.  It will get eaten.   By me, probably.

Look in any first aid kit, especially in the workplace an notice how many of them are incomplete because people will self treat and, despite their best intentions, they will not restock the kits.

Energy Gels.jpg

If it is known that there are chocolate bars in your first aid kits, they will get eaten by someone who has forgot their lunch, is on a late shift or is just bored.  And it will not be replaced.  But more importantly chocolate is no longer recommended for the treatment of hypoglycaemia as the high fat content inhibits the absorption of glucose (3,4).

Some casualties will not carry Glucogel® or Hypostop® and we would not suggest every first aid kit is stocked with similar products 'just in case', largely because of the cost.

An ideal compromise is any energy gel; the type used by athletes.  Cheap, effective, fast acting glucose which is ideally packaged for practical first aid kits.

And they taste awful, so are not likely to be eaten by a greedy guts.



  1. Stanisstreet D, Walden E, Jones C, Graveling A.  (2013).  The hospital management of hypoglycaemia in adults with diabetes mellitus. Guidelines developed by joint British Diabetes Society and Diabetes UK. (Revised September 2013). www.diabetologists-abcd.org.uk/subsite/JBDS_IP_Hypo_Adults_Revised.pdf.
  2. Caroline, N. (2011). Emergence Care in the Streets. London: Jones and Bartlet. p629.
  3. Cedermark G, Selenius M, Tullus K (1993). "Glycaemic effect and satiating capacity of potato chips and milk chocolate bar as snacks in teenagers with diabetes".  European Journal of Paediatrics.  152: 635-9
  4. Shively CA, Apgar JL, Tarka SM Jr (1986)  "Postprandial glucose and insulin responses to various snacks of equivalent carbohydrate content in normal subjects".  American Journal of Clinical Nutrition.  43: 335-342

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