Diabetic Ketoacidosis (DKA)
DKA is defined as the biochemical triad of:
- Ketonaemia ≥3 mmol/L (on ketone meter) OR significant ketonuria (≥2+ on standard urine sticks)
- Blood glucose ≥ 11mmol/L OR known diabetes mellitus*
- Bicarbonate (HCO3) below 15mmol/L AND/OR venous pH < 7.3
*Some patients may be euglycaemic or mildly hyperglycaemic (particularly those on SGLT2 inhibitors). It is important to always test for ketones.
DKA usually evolves rapidly over 24 hours, with presenting symptoms secondary to severe metabolic acidosis:
- Abdominal pain
- Nausea and vomiting
- Hyperventilation (Kussmaul’s breathing)
- Fruity odour
- Signs of volume depletion
- ABCDE management
- Fluid boluses as required if shocked/hypotensive. If unresponsive to fluids consider alternative causes of hypotension/shock
- Investigations include: FBC, U&E, VBG, blood cultures, ECG, CXR, Urine MC&S (& pregnancy test)
- Start fluids & insulin as per your local guidelines. This might be:
- 1L 0.9% sodium chloride over 1 hour
- Fixed-rate insulin infusion at 0.1 units/kg/hour – for 70kg man this would be 7 units per hour (usually made of 50 units of Actrapid in 50ml of 0.9% sodium chloride)
- Consider the underlying trigger & treat this – diarrhoea/vomiting, sepsis, ACS
Be careful of fluids in the elderly, pregnant, heart/kidney failure or 18-25 years of age – senior involvement is necessary to avoid fluid overload or cerebral oedema.
- Prescribe their long acting insulin as this prevents rebound hyperglycaemia on discontinuation of the insulin infusion (local guidelines in some places may recommend against this)
- Don’t forget VTE prophylaxis (they’re at a high risk of clots).
- Measure hourly – levels should fall at 0.5mmol/L/hour. If not available use measure bicarbonate using VBGs – levels should increase at 3mmol/L/hour.
- If not falling, check the syringe pump is working & escalate to seniors (for consideration of a higher rate of insulin infusion)
- Take a VBG at 1 hour and then 2-4 hourly thereafter (at least with every new bag of IV fluids to determine the amount of potassium in each one)
- Ensure the potassium remains in the normal range (maximum rate ≤ 10mmol/hour via a peripheral line)
- This means the 2 hourly bags would have a maximum of 20mmol/L
- Diabetes UK recommends:
- Over 5.5mmol/L – none
- Between 3.5-5.5, 40mmol/L of potassium
- Below 3.5mmol/L – senior involvement
- Ensure the patient is passing urine (otherwise the potassium might rise). Catheterise if necessary to monitor urine output.
- Measure hourly, aiming to avoid hypoglycaemia
- If the glucose falls below 14mmol/L, commence glucose 10% at 125ml/hour (1L over 8 hours) alongside 0.9% sodium chloride.
- Continue fluids & insulin (monitor for complications of pulmonary oedema & cerebral oedema)
- Insulin should not be stopped until the ketosis resolves
After 12 hours
- Look for resolution of DKA
- Ketones <0.6mmol/L or Urine: 1+ or negative
- Venous pH >7.3
- If DKA has resolved
- If eating & drinking, ideally switch at mealtime. Start their normal insulin regime, stopping the insulin infusion 1 hour after administering their subcutaneous short-acting dose
- If not eating & drinking, switch to a variable rate insulin infusion until you can do the above
- If after 24 hours, DKA has not resolved – specialist input is required as this is unusual
- Conversion to insulin for the insulin-naive should be done by a specialist team
Hyperosmolar Hyperglycaemic State (HHS, previously known as HONK)
Although often discussed separately, HHS and DKA exist on a spectrum with frequent overlap. Mortality is around 10-20% (higher than DKA) and therefore this should be managed by your seniors. All but mild cases usually require ITU input.
There is no strict definition, however characteristic features include:
- Severe hyperglycaemia (≥30mmol/L)
- Absence of significant ketoacidosis (ketones <3.0mmol/L, pH >7.3, bicarbonate >15)
- Hyperosmolality (Serum osmolality ≥320mosmol/kg [2xNa+ + Glucose + Urea])
Insidious onset over days with weight loss, polyuria and polydipsia, leading to more extreme dehydration and metabolic disturbances.
Aetiology frequently includes infection/sepsis or macrovascular events (ACS/stroke) or other illnesses that impair access to water intake.
Can present neurological symptoms due to hyperosmolality:
- Focal neurological signs
- Decreased GCS
- Osmolality >350mosmol/kg
- Sodium >160 mmol/L, hypo or hyperkalaemic
- pH <7.1
- GCS < 12 or abnormal AVPU scale (consider a nasogastric tube to reduce the risk of aspiration)
- SpO2 <92% on air (assuming normal baseline respiratory function)
- SBP <90mmHg OR HR >100 or <60 bpm
- Urine output less than 0.5ml/kg/h or Creatinine above 200
- Macrovascular event or serious co-morbidity
Management (based on Diabetes UK guidelines)
- ABCDE management. Fluid boluses as required for shocked/hypotensive patients
- Investigations include: FBC, U&E, LFTs, bone profile, magnesium, VBG, blood cultures, ECG, CXR, Urine MC&S & sputum MC&S. Have a low threshold for a Troponin.
- Fluids are continued with hourly monitoring of blood glucose
- Local guidelines may vary from those who start insulin immediately to those only after glucose ceases to fall with fluids alone.
- Usually, a fixed-rate insulin infusion scale is used at 0.05 units/kg/hour which is titrated to aim for a glucose or osmolility reduction of about 3mmol/L/hour
- Usually, electrolytes and renal function are checked every 2-4 hours
- Ensure potassium replacement & VTE prophylaxis
Further Reading & References
- UpToDate: Pathogenesis & Diagnosis of DKA/HHS
- Diabetes UK: DKA management & HHS Management
- BMJ Best Practice on HHS
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