Hypoglycaemia and Hyperglycaemia: Emergency Recognition, Assessment and Management

Learning objectives

• Define hypoglycaemia and hyperglycaemia using clinically useful glucose ranges and explain why symptoms may not match the number.
• Recognise autonomic, neuroglycopenic, dehydration and metabolic signs of glucose emergencies.
• Perform a glucose-focused ABCDE assessment, including safe capillary sampling, AVPU/GCS and ketone screening.
• Give safe first aid to a conscious patient and emergency treatment to a patient who cannot swallow.
• Differentiate uncomplicated hyperglycaemia from DKA, HHS, sepsis, stroke, intoxication and other causes of altered consciousness.
• Describe pre-hospital, emergency-department, nursing, monitoring, documentation, discharge and prevention priorities.

Glucose physiology and key definitions

Glucose is the principal fuel for the brain and an important substrate for muscle and other tissues. Insulin moves glucose into cells and suppresses hepatic glucose output. Counter-regulatory hormones (glucagon, adrenaline, cortisol and growth hormone) raise glucose during fasting or stress. Diabetes occurs when insulin production is deficient, insulin action is inadequate, or both; uncontrolled diabetes produces persistent hyperglycaemia and can damage blood vessels, nerves, eyes, heart and kidneys.

Hypoglycaemia is clinically important low glucose. In most adults with diabetes, a reading below 4.0 mmol/L (70 mg/dL) should be treated when symptoms are present. ADA terminology commonly describes level 1 as <3.9 mmol/L, level 2 as <3.0 mmol/L (54 mg/dL), and level 3 as severe hypoglycaemia requiring help from another person, regardless of the measured value. Local protocols may use slightly different thresholds.

Hyperglycaemia means glucose above the person’s target range. A single high reading is not automatically DKA or HHS. It becomes an emergency when accompanied by ketones, acidosis, severe dehydration, altered mental status, shock, vomiting, infection or rapidly worsening illness. DKA and HHS are covered here as recognition-and-stabilisation priorities; definitive insulin and electrolyte protocols require a trained hospital team.

Useful glucose ranges and clinical interpretation

Causes and risk factors for hypoglycaemia

• Excess medication: too much insulin, wrong insulin, duplicate dose, sulfonylurea (for example glibenclamide/gliclazide) or an unrecognised medication interaction.
• Insufficient intake: missed or delayed meal, vomiting, diarrhoea, fasting, swallowing difficulty, food insecurity or a child who refuses food.
• Increased use: strenuous work, exercise, prolonged walking, seizures or increased metabolic demand without carbohydrate adjustment.
• Alcohol: especially binge drinking or alcohol taken without food; delayed hypoglycaemia can occur hours later because hepatic glucose production is impaired.
• Organ failure: renal or hepatic impairment slows insulin and medicine clearance and reduces glucose production.
• Critical illness: sepsis, severe malaria, starvation, adrenal insufficiency, hypopituitarism or advanced heart failure.
• Endocrine and rare causes: insulinoma, non-islet-cell tumours, reactive hypoglycaemia and inherited metabolic disease.

Causes and risk factors for hyperglycaemia

• Missed insulin or diabetes medicines, incorrect injection technique, expired insulin or interruption of an insulin pump.
• Infection, myocardial infarction, stroke, trauma, surgery, burns, pancreatitis and other catecholamine-stressed states.
• Excess carbohydrate intake, dehydration, sedentary behaviour or inability to access medicines.
• Corticosteroids, some antipsychotics, thiazides, sympathomimetics and enteral/parenteral nutrition.
• New-onset diabetes, pregnancy-related diabetes, pancreatic disease or endocrine excess such as Cushing syndrome or thyroid storm.
• Reduced insulin action in severe obesity, renal or hepatic disease, or during acute illness.

Clinical features of hypoglycaemia

Clinical features of hyperglycaemia and dehydration

• Polyuria, polydipsia, nocturia, dry mouth, thirst, fatigue, blurred vision, weight loss and recurrent infections.
• Dehydration signs: tachycardia, postural dizziness, delayed capillary refill, weak pulses, poor skin turgor and hypotension.
• DKA clues: nausea, repeated vomiting, abdominal pain, fruity/acetone breath, deep rapid Kussmaul breathing, dehydration and progressive drowsiness.
• HHS clues: profound dehydration, very high glucose, weakness, visual change, confusion, focal deficit, seizures or coma; ketosis may be mild or absent.
• Always look for a precipitant: fever, cough, dysuria, wound, chest pain, neurological deficit, medication interruption or pregnancy.

First contact and scene priorities

1. Use standard precautions; check the scene for sharps, vomit, medicines, alcohol, pesticides and other hazards.
2. Introduce yourself, obtain consent where possible and ask a bystander to bring the patient’s diabetes card, insulin, medicines, glucose meter and glucagon kit.
3. Look for medical-alert jewellery, insulin pens, syringes, glucose tablets, ketone strips, an insulin pump and a treatment plan.
4. Assess responsiveness and breathing immediately. If unresponsive and not breathing normally, activate resuscitation procedures rather than treating presumed hypoglycaemia alone.
5. Position a conscious vomiting patient safely; place an unconscious patient who is breathing normally in the recovery position unless trauma or spinal precautions require another approach.

ABCDE assessment for a glucose emergency

A — Airway

• Check speech, gurgling, vomit, secretions, tongue obstruction and protective reflexes.
• Suction as needed, use an appropriate airway manoeuvre and prepare advanced airway support if consciousness is falling.
• Never put food, drink, gel or tablets into the mouth of a drowsy, seizing or unconscious person.

B — Breathing

• Count rate, assess depth and pattern, listen for Kussmaul breathing and measure SpO₂.
• Give oxygen for hypoxaemia or respiratory distress according to local protocol; do not use oxygen to mask poor perfusion or delay transfer.
• Deep rapid breathing with hyperglycaemia suggests metabolic acidosis and requires urgent hospital assessment.

C — Circulation

• Check pulse, blood pressure, capillary refill, temperature of extremities, hydration, urine history and signs of shock.
• Establish IV access in severe hypoglycaemia, shock, suspected DKA/HHS or inability to swallow. Take blood for laboratory testing before fluids when this does not delay resuscitation.
• Use isotonic crystalloid for clinically significant dehydration or shock under local protocol, with caution in heart or renal failure.

D — Disability

• Record AVPU and, when indicated, GCS; check pupils, speech, limb power and seizure activity.
• Measure bedside capillary glucose immediately. If the reading is unexpected, repeat with a clean, warm finger and check the meter/strip expiry.
• Check blood or urine ketones when glucose is high, the patient is unwell, type 1 diabetes is present or DKA is possible.

E — Exposure and examination

• Measure temperature, inspect injection sites, pump tubing, skin infection, pressure injuries, feet, wounds and signs of trauma.
• Look for infection, dehydration, pregnancy, alcohol or drug use and evidence of neglect or inability to obtain food/medicine.
• Maintain dignity and warmth; record all findings and response to treatment.

Focused history: SAMPLE plus glucose questions

Investigations and point-of-care checks

• Repeat capillary glucose after treatment and compare with a venous plasma sample when shock, oedema, severe dehydration, hypothermia or a peri-arrest state may make finger-stick readings unreliable.
• Blood ketones (preferably beta-hydroxybutyrate) or urine ketones; venous/arterial blood gas for pH, bicarbonate and lactate in suspected DKA or shock.
• Urea, creatinine, sodium, potassium, chloride, bicarbonate, magnesium and phosphate; renal impairment changes insulin and medicine clearance.
• Full blood count, cultures when infection is suspected, urinalysis, ECG, troponin, chest radiograph or pregnancy test as clinically indicated.
• Consider malaria testing in a febrile patient in Uganda, toxicology, cortisol, insulin/C-peptide or imaging when recurrent unexplained hypoglycaemia is present.

Management of a conscious, cooperative hypoglycaemic patient

1. Confirm the reading if possible, but treat immediately when symptoms strongly suggest a hypo and measurement is delayed.
2. Give approximately 15–20 g of fast-acting carbohydrate: glucose tablets/gel, a measured sugary drink or fruit juice. Avoid chocolate or high-fat food as the sole first treatment because absorption is slower.
3. Recheck glucose after 10–15 minutes. If it remains below 4.0 mmol/L or symptoms persist, repeat the fast carbohydrate.
4. Once recovered and above the treatment threshold, give a longer-acting carbohydrate snack or meal, especially if the next meal is more than an hour away or a long-acting insulin/sulfonylurea was involved.
5. Observe for recurrence, identify the cause and arrange clinical review when the episode was severe, recurrent, unexplained, nocturnal, alcohol-related or caused by a long-acting medicine.

Severe hypoglycaemia: patient cannot swallow, is seizing or unconscious

1. Call for advanced help, place the patient safely, protect from injury and manage airway/breathing. Do not give anything by mouth.
2. Obtain IV/IO access. Follow the facility protocol for IV glucose; a common adult approach is 10% glucose in small aliquots with repeat glucose checks, avoiding extravasation. RCUK describes 50 mL of 10% glucose initially in an unconscious adult, repeated as required up to 250 mL while monitoring response.
3. If IV access is delayed, give glucagon according to available product and local protocol (adult emergency kits commonly contain 1 mg IM/SC). Glucagon may be less effective in prolonged fasting, alcohol-related hypoglycaemia or severe liver disease.
4. Recheck glucose in about 10 minutes and after each treatment. Continue airway support and investigate other causes if consciousness does not improve promptly.
5. After recovery, give oral carbohydrate only when the swallow is clearly safe. Monitor for rebound hypoglycaemia, especially after sulfonylureas or long-acting insulin, and refer for observation.

Initial management of hyperglycaemia without shock

1. Repeat the reading, assess symptoms, check ketones when indicated and ask why glucose rose (missed insulin, infection, steroid, pump failure or dietary change).
2. Encourage appropriate oral fluids only if the patient is alert, not vomiting and has no fluid restriction. Do not force oral fluids in a confused or aspirating patient.
3. Do not advise exercise when ketones, vomiting, dehydration or severe hyperglycaemia are present; activity can worsen ketosis.
4. Arrange same-day clinical review for persistent high readings, ketones, pregnancy, type 1 diabetes, recurrent vomiting or an uncertain diagnosis.
5. Transfer urgently for red flags: hypotension, tachycardia, Kussmaul breathing, abdominal pain, repeated vomiting, severe dehydration, altered consciousness, seizure, suspected infection or inability to take medicines.

Recognising DKA and HHS

Hospital management principles for DKA/HHS

• Move to a monitored area; repeat vital signs, neurological observations, glucose, ketones, electrolytes, renal function and acid–base measurements.
• Restore circulating volume with isotonic crystalloid while reassessing blood pressure, urine output, lung sounds, sodium and cardiac/renal status.
• Insulin is prescribed only after potassium and perfusion are assessed; insulin drives potassium into cells and can precipitate dangerous hypokalaemia.
• Replace potassium and other electrolytes according to laboratory results and the hospital protocol; do not give potassium blindly.
• Treat the precipitant: infection, myocardial infarction, stroke, medication omission, pump failure, pancreatitis or steroid exposure.
• As glucose falls, dextrose may be added so insulin can continue until ketones and acidosis resolve. A “normal” glucose does not prove DKA is cured.
• HHS requires careful correction of osmolality and fluid deficit; rapid shifts may cause neurological harm. Seek senior/critical-care input early.

Nursing and EMT interventions

• Record time, glucose value, symptoms, treatment, dose, route, response and the person who administered it.
• Reassess airway, respiratory pattern, mental status, pulse, blood pressure, temperature, hydration and glucose at a frequency matched to severity.
• Maintain IV patency and inspect the site during dextrose administration; extravasation can cause tissue injury.
• Measure input/output and urine output; report oliguria, worsening dehydration, pulmonary crackles or new oedema.
• Use falls, seizure and aspiration precautions; keep suction, oxygen, airway equipment and emergency glucose available.
• Check medication administration records, insulin timing, meal intake, renal function and changes in steroids or antimicrobials.
• Communicate deterioration using SBAR and hand over the last glucose, ketone result, treatment and trend rather than a single number.

Complications to anticipate

• Hypoglycaemia: seizures, aspiration, traumatic injury, dysrhythmias, myocardial ischaemia, permanent neurological injury and death.
• Hyperglycaemia: severe dehydration, acute kidney injury, infection, thrombosis, electrolyte derangement, cerebral dysfunction and coma.
• Treatment complications: IV extravasation, hypokalaemia during insulin therapy, fluid overload, cerebral oedema or overly rapid osmolality correction.
• Recurrent or nocturnal episodes causing falls, fear of insulin, poor adherence and loss of hypoglycaemia awareness.

Prevention and patient education

• Teach the patient and family the signs of a hypo, the 15–20 g fast-carbohydrate rule, the 10–15 minute recheck and when to use glucagon.
• Carry glucose, a medical-alert card and emergency contact details; teach colleagues or family how to place the person safely and call for help.
• Never omit basal insulin without professional advice; instead follow the sick-day plan, check glucose/ketones more often and seek review early.
• Coordinate meals, insulin, exercise and alcohol. Avoid driving, heights or machinery until fully recovered and safe under local regulations.
• Review injection sites, device technique, medicine storage, expiry dates, renal function and access barriers at follow-up.
• Encourage healthy diet, regular activity when well, tobacco avoidance, blood-pressure control, foot care and routine screening for kidney, eye and nerve complications.

Clinical scenarios for EMT practice

Common errors to avoid

• Failing to check glucose in every patient with altered consciousness, seizure, collapse or unexplained aggression.
• Giving oral food or drink to a drowsy patient, or assuming a normal first reading excludes a serious illness.
• Treating the number without assessing the cause, ketones, hydration, potassium, infection and medication history.
• Giving insulin for hyperglycaemia without a protocol, potassium result or a monitored setting.
• Stopping assessment after the patient “wakes”; recurrence, stroke, sepsis, overdose or head injury may coexist.

Revision questions

1. What glucose threshold should prompt treatment of a symptomatic adult, and why should treatment not be delayed when the patient is deteriorating?
2. List five adrenergic and five neuroglycopenic features of hypoglycaemia.
3. Explain the difference between a patient who can safely swallow and one who requires IV glucose or glucagon.
4. Why can beta-blockers, renal failure and alcohol make hypoglycaemia harder to recognise or longer lasting?
5. Which findings suggest DKA or HHS rather than uncomplicated hyperglycaemia?
6. Why must potassium and perfusion be assessed before hospital insulin therapy?
7. Write an SBAR handover for the patient in Scenario 3.

Key takeaways

References for further study

• American Diabetes Association. Standards of Care in Diabetes—2026: Glycemic Goals, Hypoglycemia, and Hyperglycemic Crises.
• Resuscitation Council UK. The ABCDE Approach — bedside glucose assessment and IV 10% glucose guidance.
• NHS. Low blood sugar (hypoglycaemia) — symptoms, 15-minute treatment, glucagon and prevention.
• World Health Organization. Diabetes fact sheet — physiology, symptoms, complications and prevention.
• Use current Uganda Ministry of Health, facility and prescriber protocols for medication concentrations, paediatric doses, DKA/HHS pathways and referral.