Hypoglycaemia: Assessment and Management for Students
Updated: 21 hours ago
Hypoglycaemia is one of the most common diabetic emergencies, and one of the most rewarding to treat. A patient who is confused, aggressive or unresponsive can be talking normally within minutes of the right treatment. It is also easy to miss, because it can look like a stroke, a seizure, intoxication or a behavioural problem. That is why checking a blood glucose level is a core part of assessing any patient with an altered conscious state.
What counts as hypoglycaemia
In people with diabetes treated with insulin or certain oral medications, a blood glucose level below 4.0 mmol/L is generally treated as hypoglycaemia in Australia. A level below 3.0 mmol/L is considered clinically significant. Severe hypoglycaemia is defined by its effect rather than a number: a patient who needs help from someone else to recover because they are confused, drowsy, unconscious or having a seizure.
Why it happens
The brain depends on a steady supply of glucose. Hypoglycaemia happens when there is too much glucose lowering medication relative to the glucose available. Common causes include:
Too much insulin, or insulin given at the wrong time.
Sulfonylurea medications, which can cause prolonged or recurrent hypoglycaemia.
A missed or delayed meal, or less carbohydrate than usual.
More physical activity than usual.
Alcohol, which reduces the liver's ability to release glucose.
Illness, vomiting or worsening kidney function.
Signs and symptoms
Symptoms fall into two broad groups. The first are warning signs caused by the body's stress response: sweating, shaking, a fast heart rate, palpitations, hunger, anxiety and pallor. The second come from the brain not getting enough glucose: confusion, difficulty concentrating, slurred speech, unusual behaviour, irritability, drowsiness, seizures and loss of consciousness.
Some people, particularly those who have had diabetes for many years or who have frequent low levels, lose their early warning signs. This is called impaired awareness of hypoglycaemia, and it means the first sign may be confusion or collapse.
Any patient with an altered conscious state needs a blood glucose level. Check it, don't assume it.
Management when the patient can swallow
If the patient is conscious, cooperative and able to swallow safely, give fast acting carbohydrate by mouth. Around 15 grams is a common starting amount, for example a small glass of fruit juice, regular soft drink or several jellybeans. Recheck the blood glucose level after about 15 minutes and repeat the fast acting carbohydrate if it is still low.
Once the level has recovered, the patient needs some longer acting carbohydrate, such as a sandwich, a piece of fruit or their next meal if it is due, to stop the level falling again.
Management when the patient cannot swallow safely
Never give food or drink to a patient who is drowsy, unconscious, seizing or unable to protect their airway, because of the risk of aspiration. Place them in a safe position, manage the airway and call for help. Treatment options at this stage include intramuscular glucagon and intravenous glucose, according to your clinical practice guidelines and scope of practice. Once the patient is alert and able to swallow, follow with oral carbohydrate.
After the episode
Find out why it happened. A patient on a sulfonylurea, a patient with a deliberate or accidental insulin overdose, or a patient who cannot eat because of illness is at high risk of the level falling again, and usually needs further assessment and monitoring. Make sure the patient has a responsible adult with them, access to food and a plan, and follow your service's guidance on when transport to hospital is required.
Special situations
Older adults
Older patients are more likely to have hypoglycaemia and less likely to show the classic warning signs. Confusion, falls, slurred speech or new weakness can be mistaken for a stroke or dementia. Sulfonylurea medications are a particular risk because their effect can last for many hours, so an older patient on these tablets can drop low again after an initial recovery.
Children
Children have smaller glucose stores and can become hypoglycaemic quickly when they are unwell, vomiting or not eating. In a child with type 1 diabetes, a change in behaviour such as unusual irritability, quietness or clumsiness may be the first sign. Families usually have a written hypoglycaemia plan from their diabetes team, so ask the carer what they have already given and follow that plan alongside your guidelines.
Alcohol
Alcohol reduces the liver's ability to make new glucose, and the effect can last for hours after drinking stops. An intoxicated patient who is drowsy may also be hypoglycaemic, and the smell of alcohol should never stop you checking a blood glucose level.
Insulin pumps and glucose sensors
Many people with type 1 diabetes now use continuous glucose monitors and insulin pumps. Sensor readings measure fluid under the skin and lag several minutes behind the blood, so confirm a low or unexpected reading with a finger prick test. Remember that a pump may keep delivering insulin while the patient is low, so follow the patient's own plan and your guidelines about pausing or removing it.
Hypoglycaemia and its mimics
Hypoglycaemia can look like a stroke, a seizure, a head injury, intoxication or a mental health crisis, and it can also happen alongside them. A patient who fell because they were hypoglycaemic may also have hit their head. If the patient does not return completely to normal once their glucose level is corrected, keep looking for another cause.
Common student mistakes
Not checking a blood glucose level in a confused or aggressive patient.
Giving oral carbohydrate to a patient who cannot protect their airway.
Forgetting the longer acting carbohydrate once the level recovers.
Not rechecking the level after treatment.
Leaving a patient on a sulfonylurea alone after an apparently full recovery.
Conclusion
Hypoglycaemia is common, dangerous and very treatable. Check a blood glucose level in every altered patient, treat with oral carbohydrate when it is safe and with glucagon or intravenous glucose when it isn't, follow up with longer acting carbohydrate, and always ask why it happened.
References
International Hypoglycaemia Study Group. Glucose concentrations of less than 3.0 mmol/L (54 mg/dL) should be reported in clinical trials. Diabetes Care. 2017;40(1):155.
Seaquist ER, Anderson J, Childs B, et al. Hypoglycemia and diabetes: a report of a workgroup of the American Diabetes Association and the Endocrine Society. Diabetes Care. 2013;36(5):1384.
Australian and New Zealand Committee on Resuscitation (ANZCOR). Guideline 9.2.9: First Aid for Diabetic Emergencies. Australian Resuscitation Council.
Diabetes Australia. Hypoglycaemia (hypos). Canberra: Diabetes Australia.
American Diabetes Association Professional Practice Committee. 6. Glycemic Goals and Hypoglycemia: Standards of Care in Diabetes 2024. Diabetes Care. 2024;47(Suppl 1):S111.
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Disclaimer: This article is general education for students. It is not medical advice, and it does not replace your service's clinical practice guidelines, your educators or your local protocols.
