You’ve found an unwell dehydrated, diabetic patient who is hyperglycaemic. They are ketotic or have significant hyperglycaemia alone (>30mmol/L) at a first glance, and so you suspect Diabetic Ketoacidosis (DKA) or Hyperosmolar Hyperglycaemic State (HHS) respectively.
Diabetic Ketoacidosis (DKA)
DKA is defined as the biochemical triad of:
- Ketonaemia ≥3 mmol/L (hand-held Ketone Meter) OR significant Ketonuria (≥2+ on standard urine dip-sticks)
- Blood glucose ≥ 11mmol/L OR known Diabetes Mellitus*
- Bicarbonate (HCO3) below 15mmol/L AND/OR venous pH < 7.3
*Patients may be euglycaemic or only mildly hyperglycaemic (particularly those on SGLT2 inhibitors). It is important to always test for ketones.
Clinical Features
DKA usually evolves rapidly over 24 hours, with symptoms often being due to severe metabolic acidosis:
- Abdominal pain.
- Nausea and vomiting.
- Hyperventilation (Kussmaul breathing: deep and rapid).
- Fruity odour (acetone breath released as a by-product of Ketosis i.e. process by which fat is broken down for an energy source).
- Signs of volume depletion.
Severe DKA
- Blood ketones > 6mmol/L.
- Bicarbonate < 5mmol/L.
- Venous/arterial pH < 7.0.
- Hypo or hyperkalaemia on admission (ensure cardiac monitoring is attached to quickly catch any life threatening arrhythmias!*).
- GCS < 12 or abnormal AVPU tool rating (consider an nasogastric tube to reduce the risk of aspiration, secondary to this altered mental state.)
- SpO2 <92% on air (assuming normal baseline respiratory function).
- SBP <90mmHg OR HR >100 or <60 bpm.
*Beware that insulin (our main of treatment for DKA, along with liberal fluids replacement) will cause the potassium to fall further!
For the following, I’ve used the Diabetes UK guidelines.
Immediate Management (1st hour)
- ABCDE resuscitation.
- 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 for women of child bearing age!)
- 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 (dehydration increases the 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.
Once a team is satisfied their patients DKA has resolved, the ability to safely convert their ins line regime from infusion to subcutaneous injections will depend on their eating and drinking ability.
- Eating & drinking: ideally switch at mealtime. Start their normal insulin regime, stopping the insulin infusion 1 hour after administering their subcutaneous short-acting dose.
- 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 too.
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)
- Hypovolaemia
*Formula for this being: 2 (Na+) + Glucose + Urea (all in mmol/L)
Clinical Features
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 and/or stroke), ans well other illnesses that impair access to water intake such as gastroenteritis.
Can present with neurological signs due to the effects of hyperosmolality on the central nervous system:
- Focal neurological signs
- Seizures
- 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.
- Hypothermia.
- Macrovascular event or serious co-morbidity.
Management (based on Diabetes UK guidelines)
- ABCDE resuscitation. Fluid boluses as required for shocked/hypotensive patients.
- Investigations include: FBC, U&E, LFTs, bone profile, magnesium, VBG, blood cultures, ECG, CXR, Urine & 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 osmolality 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.
