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Management of diabetic emergencies

Please note OSCEstop content is for educational purposes only and not intended to inform clinical practice. OSCEstop and authors take no responsibility for errors or the use of any information displayed. 

Normal glucose values (mmol/L)


  • Non-diabetic (random) = 4-7.8
  • Type 1 diabetic = 4-9
  • Type 2 diabetic = 4-8.5
  • Hyperglycaemia = >11
  • Hypoglycaemia = <4
  • Normal capillary ketones = <0.6

Diabetic ketoacidosis (DKA)

In DKA, a relative lack of insulin results in hyperglycaemia as cells are unable to take up glucose – ‘starvation in the midst of plenty’. This causes cells to switch to a fatty acid metabolism, resulting in the production of acidic ketones.


  • Follow usual ABCDE approach 

2. Confirm diagnosis

  • Ensure you include VBG, capillary/urine ketones and glucose measurement
  • Confirm diagnosis (all of):
    • Glucose >11mmol/L (NB. glucose may be normal in some circumstances – ‘euglycaemic DKA’, e.g. if taken insulin recently, on SGLT-2 inhibitor, during pregnancy)
    • pH <7.3 or HCO3–  <15mmol/L
    • Capillary ketones >3mmol/L (or ++ urinary ketones)

3. Intravenous fluids

NB: dehydration is more lethal than hyperglycaemia.

  • 1L saline over 1 hour (or faster if hypotensive) – without potassium
  • 1L saline over 2 hours
  • 1L saline over 2 hours
  • 1L saline over 4 hours
  • 1L saline over 4 hours
  • 1L saline over 6 hours
  • 1L saline over 6 hours

After the 1st litre, add potassium chloride to each litre depending on VBG results:

  • K+ > 5.5 = nil
  • K+ 3.5-5.5mmol/L = 40mmol KCl
  • K+ <3.5mmol/L = senior review as additional potassium required

4. Fixed rate insulin infusion

  • IV insulin infusion 0.1unit/kg/hour from 50 units human soluble rapid-acting insulin (e.g. Actrapid) in 50ml 0.9% saline
    • NB: maximum rate is 15 units per hour.                                               
  • When capillary glucose is <14mmol/L, give 10% IV glucose at 125ml/hour in addition to the 0.9% saline – but reduce the saline rate to account for extra fluid. Glucose is used so that insulin can continue to drive more glucose into cells to reduce ketosis and acid production.

5. Investigation to find cause

  • History
  • Top to tail examination (including looking diabetic foot exam)
  • Bloods (FBC, glucose, U&Es, LFTs, osmolality, CRP)
  • Blood culture
  • MSU
  • Chest X-ray
  • ECG

6. Other priorities

  • Treat the cause
  • Consider high dependency unit admission if: ketones >6mmol/L, HCO3– <5mmol/L or pH <7.1, GCS <12, SBP <90mmHg, sats <92% on air, HR >100/<60bpm, potassium <3.5mmol/L on admission
  • Continue patient’s long-acting insulin throughout and start long-acting insulin (Lantus 0.1-0.2 units/kg once daily s/c) if it is a new presentation
  • Do not continue any other types of insulin and turn off insulin pumps while on fixed/variable-rate insulin infusions
  • Check capillary glucose and ketones hourly and VBG at 1 hour, 2 hours, then 2-hourly to assess acid-base balance, potassium and glucose
    • Aim to increase HCO3– by 3mmol/hour, reduce glucose by 3mmol/hour and reduce ketones by 0.5mmol/L/hour
    • Insulin can be increased by 1 unit/hour if target is not reached
  • When the acid-base abnormality is fully corrected (i.e. pH >7.3) and capillary ketones are <0.6mmol/L (should occur within 24 hours) and the patient is eating and drinking, restart their normal insulin regimen at a mealtime
  • If abnormal physiology is corrected but the patient is still not eating and drinking (or it is not a mealtime), start a variable rate insulin infusion
  • Ensure VTE prophylaxis is prescribed
  • Education and medication review

Reference: Joint British Diabetes Societies for Inpatient Care ‘The management of diabetic ketoacidosis in adults’ 2023

Hypermosmolar hyperglycaemic state (HHS)

Hyperglycaemia develops slowly as a result of illness/dehydration and causes hyperosmolality in the intravascular compartment and severe cellular dehydration due to prolonged osmotic diuresis. Notably, there is no acidosis or ketosis because basal insulin levels allow sufficient cellular glucose uptake to prevent fatty acid metabolism. The main dangers are dehydration and a prothrombotic state. Serum osmolality (mainly determined by sodium and glucose) must be closely monitored to avoid over rapid correction, which carries a risk of osmotic demyelination syndrome.

Confirm diagnosis

  • Confirm diagnosis
    • Marked hyperglycaemia (≥30mmol/L) without acidosis or significant ketosis
    • Serum osmolality ≥320mmol/L
    • Hypovolaemia


  • Rehydrate with 0.9% saline (fluids given at a similar rate as in DKA initially)
  • Check serum osmolality (may be calculated by 2x sodium + glucose + urea) hourly initially – adjust fluid (± insulin) rate accordingly to avoid over rapid correction, aim to reduce by 3-8mosmol/kg/hr
  • Start IV insulin infusion at 0.05units/kg/hour only if glucose is not falling with fluids alone or there is ketosis (but rehydrate first)
  • VTE prophylaxis (high risk of VTE)
  • Look for and treat cause 
  • Hold metformin for 2 days (it causes a metabolic acidosis)

Reference: Joint British Diabetes Societies for Inpatient Care ‘The management of hyperosmolar hyperglycaemic state (HHS) in adults’ 2022

Hyperglycaemia without DKA/HHS

  • Exclude DKA (check ketones ± VBG) and HHS (VBG and bloods to check osmolality if glucose ≥30mmol/L)
  • Rehydrate if necessary
  • STAT dose of rapid-acting (e.g. Novorapid) or short-acting (e.g. Actrapid) insulin dose can be used
    • Type 1: 1 unit decreases blood glucose by 3mmol/L (aim glucose <12mmol/L)
    • Type 2 (more insulin resistant): 0.1unit/kg (aim glucose <14mmol/L)
  • Identify and correct cause (and check patient has taken insulin normally)
  • Adjust normal insulin regimen as necessary
  • Recheck glucose in 1 hour and reassess


A dangerous medical emergency!

  • Unconscious
    • 200ml 10% glucose or 100ml 20% glucose IV STAT (repeat as necessary)
    • Glucagon 1mg IM if no IV access (once only)
  • Conscious but cannot swallow
    • 2 tubes 40% glucose gel around teeth if mild and patient conscious
  • Can swallow:
    • 15-20g fast-acting carbohydrate (e.g. 5 glucose/dextrose tablets, 150-200ml fruit juice/Lucozade)
    • AND long-acting carbohydrates
  • All:
    • Check capillary glucose 10 minutes later, repeat treatment as needed 
    • Give long-acting carbohydrate when able to swallow (e.g. biscuits, toast)
    • Determine and correct cause
    • Don’t omit insulin/tablets afterwards (risk of rebound hyperglycaemia) – reduce dose instead

Reference: Joint British Diabetes Societies for Inpatient Care ‘The hospital management of hypoglycaemia in adults with diabetes mellitus’ 2023


What are 3 common causes of hyperglycaemia?

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What are 3 common causes of hypoglycaemia?

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Why can insulin be dangerous in HHS?

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OSCE stations

  1. Diabetic ketoacidosis A-E assessment
  2. Diabetic ketoacidosis interpretation
  3. Lots more here!

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