Diabetic Ketoacidosis Guidelines Explained

Algorithm at a glance

Diabetic ketoacidosis (DKA) is a core endocrine emergency in UK Emergency Medicine and a frequent MRCEM and FRCEM topic. It tests rapid recognition, safe protocol-based treatment, interpretation of blood gas and electrolyte results, and awareness of common management errors. In the ED, the priorities are to confirm the diagnosis early, start fluid resuscitation, give fixed-rate intravenous insulin safely, replace potassium appropriately, identify the precipitant, and monitor for failure to improve or complications.

Why the Diabetic Ketoacidosis Guidelines Matter in the ED

DKA is common, time-critical, and potentially fatal. It may present clearly with marked hyperglycaemia and acidosis, but it can also be subtle, especially in euglycaemic DKA associated with SGLT2 inhibitors, pregnancy, starvation, or prolonged vomiting.

It is highly examinable because it is both protocol-driven and safety-critical. Candidates lose marks by:

• Starting insulin before checking potassium
• Using a variable-rate insulin infusion instead of a fixed-rate insulin infusion
• Stopping insulin when glucose normalises despite ongoing ketosis
• Forgetting to add dextrose once glucose falls
• Missing euglycaemic DKA
• Failing to continue basal long-acting insulin
• Using the adult pathway in children
• Giving bicarbonate routinely

For UK adult practice, the key reference is the Joint British Diabetes Societies for Inpatient Care (JBDS-IP) adult DKA guidance. In children and young people, use BSPED and local paediatric pathways rather than an adult protocol.

Key Definitions

DKA is a metabolic emergency caused by absolute or relative insulin deficiency, leading to hyperglycaemia, ketonaemia, and metabolic acidosis.

In UK adult practice, diagnose DKA when all of the following are present:

Important caveat: glucose does not need to be markedly raised. Euglycaemic DKA is still DKA if there is significant ketonaemia with metabolic acidosis in the right clinical context.

Blood ketones are preferred over urine ketones for diagnosis and monitoring because bedside beta-hydroxybutyrate reflects the predominant ketone in DKA and responds more reliably to treatment.

Essential Pathophysiology

The exam-relevant physiology is straightforward:

• Insulin deficiency and excess counter-regulatory hormones drive lipolysis and ketogenesis
• Ketone accumulation causes a high anion gap metabolic acidosis
• Hyperglycaemia causes osmotic diuresis with major water and electrolyte loss
• Total body potassium is depleted even if the initial serum potassium is normal or high
• Once insulin is started, potassium shifts intracellularly and serum potassium may fall rapidly

The key practical implication is that insulin is given to stop ketone production, not just to lower glucose. That is why insulin must continue after glucose falls, with dextrose support if needed, until the ketoacidosis has resolved.

Clinical Presentation

Typical features include:

• Polyuria and polydipsia
• Vomiting
• Abdominal pain
• Dehydration
• Tachycardia
• Tachypnoea or Kussmaul breathing
• Weakness and malaise
• Confusion or reduced conscious level in more severe cases

Common precipitants include:

• Infection
• Missed insulin or insulin omission
• New presentation of type 1 diabetes
• Insulin pump failure
• Myocardial infarction
• Stroke
• Pancreatitis
• Surgery or trauma
• Steroids
• Pregnancy
• SGLT2 inhibitor use

Always ask specifically about insulin regimen, missed doses, pump use, recent illness, vomiting, reduced intake, pregnancy, and drugs including SGLT2 inhibitors.

Red Flags and High-Risk Features

These features should prompt senior review and consideration of level 2 or level 3 care:

• Blood ketones more than 6 mmol/L
• Venous or arterial pH less than 7.1
• Bicarbonate less than 5 mmol/L
• Potassium less than 3.5 mmol/L on admission
• GCS less than 12 or abnormal AVPU
• Systolic blood pressure less than 90 mmHg
• Oxygen saturation less than 92% on air, if not explained by chronic lung disease
• Pulse more than 100 or less than 60 beats per minute
• Anion gap more than 16
• Urine output less than 0.5 mL/kg/hour
• Shock, severe dehydration, or persistent hypotension
• Concern about mixed DKA/HHS
• Failure to meet treatment targets
• Neurological deterioration

These are indicators for escalation, not a substitute for clinical judgement. A patient with severe acidosis, shock, reduced consciousness, or mixed pathology is not suitable for routine ward-level management.

Differential Diagnosis

Important differentials and mimics include:

Abdominal pain is common in DKA, but do not dismiss focal tenderness, guarding, or persistent pain after treatment. Consider pancreatitis, appendicitis, bowel pathology, or another surgical cause.

Initial ED Assessment

Use an ABCDE approach and start treatment alongside assessment.

Airway

• Airway compromise is unusual in uncomplicated adult DKA
• Reduced GCS, vomiting, aspiration risk, or exhaustion require urgent senior and critical care input

Breathing

• Assess respiratory rate, oxygen saturation, work of breathing, and pattern
• Kussmaul respirations suggest significant metabolic acidosis
• Give oxygen only if hypoxic

Circulation

• Assess pulse, blood pressure, capillary refill, peripheral perfusion, and urine output
• Insert IV access promptly
• Start 0.9% sodium chloride early
• Persistent hypotension after initial fluid should trigger reassessment for sepsis, haemorrhage, ACS, or another cause

Disability

• Document GCS and baseline mental state
• Confusion or reduced consciousness indicates severe illness or mixed pathology
• Cerebral oedema is rare in adults, but unexplained neurological deterioration requires urgent senior review and critical care involvement while considering other causes such as severe acidosis, hyperosmolarity, stroke, sepsis, or intoxication

Exposure

• Look for infection source, pump disconnection, cellulitis, trauma, abdominal signs, pregnancy clues, and medication triggers

Investigations

Essential immediate tests:

• Capillary blood glucose
• Venous blood gas: pH, bicarbonate, potassium, lactate if available
• Blood ketones
• Urea and electrolytes, including creatinine
• Full blood count
• ECG
• CRP if infection suspected

Additional tests according to likely precipitant:

• Urinalysis
• Pregnancy test where relevant
• Blood cultures if sepsis suspected
• Urine culture if UTI suspected
• Chest X-ray if respiratory symptoms, fever, or hypoxia
• Troponin if chest pain, ECG changes, or ACS concern
• Lipase or amylase if pancreatitis suspected
• Serum osmolality if concern for HHS or mixed DKA/HHS

Useful interpretation points:

• Venous blood gas is usually sufficient; arterial gas is not routinely required unless oxygenation or ventilation assessment is needed
• Corrected sodium can help assess free water deficit in marked hyperglycaemia
• A high anion gap supports ketoacidosis
• If ketones are falling but acidosis persists after substantial saline, consider hyperchloraemic acidosis rather than ongoing DKA

Management in the Emergency Department

Adult DKA management in the ED should follow the local adult DKA pathway, usually based on JBDS guidance. The key principles are fluid replacement, safe insulin therapy, potassium management, treatment of the precipitant, and close monitoring.

Immediate priorities

1. Start 0.9% sodium chloride
2. Send urgent VBG, ketones, and U&Es
3. Check potassium before starting insulin
4. Start fixed-rate intravenous insulin infusion once potassium is safe
5. Continue long-acting basal insulin if already prescribed
6. Add potassium to fluids according to the measured level and local chart
7. Add 10% glucose when glucose falls below 14 mmol/L, or earlier in euglycaemic DKA if needed
8. Identify and treat the precipitant in parallel

Step 1: Fluid resuscitation

Initial fluid in adults is 0.9% sodium chloride.

• A typical starting approach is 1 litre over the first hour
• If shocked, give an initial fluid bolus promptly and reassess
• Use more cautious fluid replacement in heart failure, advanced renal impairment, frailty, or mixed DKA/HHS
• Reassess haemodynamics, urine output, and biochemical response regularly

Fluid replacement is usually the first treatment step. It improves perfusion, reduces counter-regulatory stress, and lowers glucose even before insulin is started.

Step 2: Potassium assessment before insulin

Send urgent VBG and U&Es immediately. In practice, potassium is often available rapidly from the initial gas. Start insulin once potassium is known to be safe.

Exact potassium concentration and infusion rate must follow local policy and pharmacy-approved fluid bags. Renal function and urine output matter.

Step 3: Fixed-rate intravenous insulin infusion

The standard adult treatment is a fixed-rate intravenous insulin infusion (FRIII), not a variable-rate insulin infusion.

• Start FRIII at 0.1 units/kg/hour in most adults
• Continue the patient’s usual long-acting basal insulin
• Do not stop insulin just because glucose normalises

JBDS 2023 advises that once glucose falls below 14 mmol/L, the FRIII can be reduced to 0.05 units/kg/hour while 10% glucose is commenced and treatment of ketosis continues. This is highly exam-relevant, but in practice follow local policy if it differs.

Step 4: Dextrose when glucose falls

• When glucose falls below 14 mmol/L, start 10% glucose infusion
• Continue insulin because the target is clearance of ketones and acidosis, not simply normalisation of glucose
• In euglycaemic DKA, dextrose may need to be started earlier

Step 5: Ongoing monitoring

Monitoring is a major exam area and a major safety issue.

Catheterisation is not routine but may be needed if urine output cannot otherwise be monitored or the patient is critically unwell.

Step 6: Treatment targets

Common adult treatment targets are:

• Blood ketones falling by about 0.5 mmol/L/hour
• Bicarbonate rising by about 3 mmol/L/hour
• Glucose falling by about 3 mmol/L/hour

If targets are not being met, reassess immediately:

• Is the diagnosis correct?
• Is the insulin infusion running and connected properly?
• Has the cannula tissued?
• Has enough fluid been given?
• Is there ongoing sepsis or another precipitant?
• Is this mixed DKA/HHS?
• Does the patient need HDU or ICU review?

Step 7: Treat the precipitant

DKA management is incomplete unless the trigger is sought and treated.

• Give antibiotics promptly if sepsis is suspected
• Investigate and treat ACS, stroke, pancreatitis, or other acute pathology
• Address missed insulin, psychosocial issues, or pump failure
• Stop SGLT2 inhibitors during the acute episode

Electrolytes and adjuncts

Potassium

• Total body potassium is depleted in DKA
• Hypokalaemia is a major treatment hazard
• Use ECG monitoring if potassium is significantly abnormal

Bicarbonate

• Do not give bicarbonate routinely in adult DKA
• Routine bicarbonate therapy is not recommended and may be harmful
• If there are exceptional circumstances, involve senior and critical care teams

Phosphate

• Routine phosphate replacement is not recommended
• Consider specialist advice if there is severe deficiency or specific complications

Thromboprophylaxis

• Adults with DKA are at increased thrombotic risk
• Assess VTE risk and prescribe thromboprophylaxis unless contraindicated, according to local policy

When is DKA resolved?

Resolution is judged by clearance of ketoacidosis, not by glucose alone. Common adult resolution criteria are:

• Blood ketones less than 0.6 mmol/L
• Venous pH more than 7.3
• Bicarbonate more than 15 mmol/L
• The patient is clinically improving and able to eat and drink if appropriate

Transition from IV insulin to subcutaneous insulin

Do not stop the IV insulin infusion until DKA has resolved and a safe subcutaneous insulin plan is in place.

• Continue basal long-acting insulin throughout if already prescribed
• If switching to a subcutaneous regimen, ensure overlap between subcutaneous insulin and stopping IV insulin, according to local policy
• Restart oral intake when clinically appropriate
• Involve the diabetes team early

If the patient uses an insulin pump, do not rely on the pump during acute DKA treatment. Standard IV fixed-rate insulin should be used. The pump can usually be restarted only after DKA has resolved and specialist review has occurred.

Disposition, Referral and Follow-Up

Most patients with DKA require admission. The key decision is whether ward care is sufficient or whether level 2 or level 3 care is needed.

Consider HDU or ICU for:

• Severe acidosis
• Shock or persistent hypotension
• Reduced GCS
• Significant potassium disturbance
• Mixed DKA/HHS
• Failure to improve on standard treatment
• Need for invasive monitoring or airway support

Early referral is often needed to:

• Acute medicine or endocrinology/diabetes team
• Critical care if severe or failing treatment
• Obstetrics in pregnancy
• Paediatrics in children and young people

Before discharge, ensure:

• DKA has fully resolved
• The precipitant has been addressed
• Insulin regimen is reviewed
• Sick day rules are reinforced
• Pump issues are resolved if relevant
• Specialist diabetes follow-up is arranged

Special Groups

Children and young people

Do not use the adult DKA pathway in children. Paediatric DKA differs in fluid strategy, insulin dosing, and concern about cerebral oedema. Use BSPED guidance and local paediatric pathways, and involve paediatric senior staff early.

Exam-safe rule: if the patient is a child or young person on a paediatric pathway, stop and switch to paediatric guidance.

Pregnancy

Pregnancy increases the risk of DKA and euglycaemic DKA. It can develop at lower glucose levels and may occur rapidly. Involve obstetrics and diabetes teams early. Maternal resuscitation takes priority, but fetal wellbeing also matters.

SGLT2 inhibitor-associated euglycaemic DKA

Think of this when there is acidosis and ketonaemia with normal or only mildly raised glucose, especially in a patient taking empagliflozin, dapagliflozin, canagliflozin, or ertugliflozin.

• Do not be falsely reassured by a near-normal glucose
• Treat as DKA
• Dextrose may be needed earlier
• Stop the SGLT2 inhibitor

Elderly patients and mixed DKA/HHS

Older adults may have mixed pathology with severe dehydration, hyperosmolarity, and significant comorbidity. Consider mixed DKA/HHS if glucose is very high, osmolality is raised, or mental status is disproportionately impaired. These patients often need slower correction, closer monitoring, and senior input.

Renal impairment and heart failure

Fluid replacement and potassium management need greater caution. These patients are at higher risk of fluid overload and dangerous potassium shifts. Senior review is essential.

Immunosuppressed patients

Have a low threshold to look for sepsis, occult infection, and atypical triggers. DKA may be the first sign of serious underlying illness.

Common Pitfalls

• Diagnosing or excluding DKA on glucose alone
• Missing euglycaemic DKA
• Using urine ketones alone to monitor response
• Starting insulin before potassium is known to be safe
• Using VRIII instead of FRIII
• Stopping insulin when glucose normalises
• Forgetting 10% glucose once glucose falls
• Not continuing basal insulin
• Ignoring failure to meet treatment targets
• Not looking for the precipitant
• Giving bicarbonate routinely
• Applying the adult pathway to a child
• Missing mixed DKA/HHS

FRCEM and MRCEM Exam Tips

A strong viva or OSCE answer sounds like this:

“This is adult DKA until proven otherwise. I would assess with ABCDE, start 0.9% sodium chloride immediately, send urgent venous gas, blood ketones and U&Es, check potassium, and start a fixed-rate IV insulin infusion once potassium is safe. I would continue basal long-acting insulin, replace potassium according to the measured level and local chart, add 10% glucose when glucose falls below 14 mmol/L, monitor ketone clearance, bicarbonate rise, glucose fall and urine output, and identify and treat the precipitating cause in parallel. I would escalate early if there is severe acidosis, shock, reduced GCS, significant potassium abnormality, or failure to improve.”

High-yield exam facts:

• Adult diagnostic thresholds: ketones more than 3 mmol/L, glucose more than 11 mmol/L or known diabetes, pH less than 7.3 and/or bicarbonate less than 15 mmol/L
• Blood ketones are preferred to urine ketones
• Use FRIII, not VRIII
• Continue basal insulin
• Add 10% glucose when glucose falls below 14 mmol/L
• JBDS 2023: consider reducing FRIII to 0.05 units/kg/hour once glucose is below 14 mmol/L while continuing dextrose and treating ketosis, subject to local policy
• Bicarbonate is not routine
• Children need a paediatric pathway

How This Appears in SBA Questions

Typical question stems:

• A young adult with vomiting, abdominal pain, tachypnoea, glucose 24, ketones 5.8, pH 7.12
• A patient on empagliflozin with vomiting, ketones 4.2, pH 7.21, glucose 9.8
• A DKA patient whose glucose has fallen to 11 mmol/L but ketones remain elevated
• A DKA patient with potassium 3.1 mmol/L on the initial gas
• A confused dehydrated older patient with glucose 38 mmol/L, ketones 3.5, and high osmolality

Key discriminator clues:

• Normal or mildly raised glucose does not exclude DKA
• Low potassium means insulin must wait until potassium is corrected
• Normal glucose with ongoing ketosis means continue insulin and add dextrose
• Very high glucose and osmolality suggest HHS or mixed DKA/HHS
• Reduced GCS, shock, or severe acidosis means escalation

Common wrong answer traps:

• Start VRIII
• Stop insulin because glucose is normal
• Give bicarbonate for acidosis
• Use urine ketones to judge resolution
• Manage a child with the adult pathway
• Ignore the precipitant

Key Takeaways

• Diagnose DKA using ketones, acidosis, and glucose or known diabetes; do not rely on glucose alone
• Think of euglycaemic DKA in SGLT2 inhibitor use, pregnancy, starvation, and prolonged vomiting
• Start 0.9% sodium chloride early
• Check potassium before starting insulin
• Use fixed-rate IV insulin, not variable-rate insulin, for DKA treatment
• Continue basal long-acting insulin
• Add potassium according to the measured level and local chart
• Add 10% glucose when glucose falls below 14 mmol/L, or earlier if needed in euglycaemic DKA
• Do not stop insulin until ketoacidosis has resolved
• Monitor ketones, bicarbonate, glucose, potassium, observations, and fluid balance closely
• Failure to meet treatment targets should trigger immediate reassessment and escalation
• Do not give bicarbonate routinely
• Always identify and treat the precipitating cause
• Do not use the adult pathway in children

Further Reading

• Joint British Diabetes Societies for Inpatient Care (JBDS-IP): The Management of Diabetic Ketoacidosis in Adults
• BSPED guideline for the management of children and young people under 18 years with diabetic ketoacidosis
• NICE guidance on diabetes in children and young people
• RCEM Learning resources on diabetic emergencies and euglycaemic DKA
• NICE guidance on type 1 diabetes and type 2 diabetes where relevant to ongoing care

Related on EM Final Exams

• Top 10 RCEM Guidelines You Must Know for FRCEM
• Sepsis NICE NG51 What You Actually Need to Know
• Top 15 Paediatric Emergencies for MRCEM
• Most Examined NICE Guidelines for Emergency Medicine

Authoritative Sources

• Association of British Clinical Diabetologists (JBDS-IP)
• NICE guidance

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