Can DKA be diagnosed with a normal glucose?

Yes. The JBDS criteria accept known diabetes in place of a glucose above 11 mmol/L, and the 2023 revision specifically addresses euglycaemic DKA in people taking SGLT2 inhibitors. The drug should be stopped and a Yellow Card submitted.

Why does fluid come before insulin in DKA?

Because restoring circulating volume is the priority, and starting insulin into a contracted, potassium-depleted circulation risks hypotension and hypokalaemia. JBDS sets time zero at the start of intravenous fluid, with insulin started within that first hour.

What does 'consider reducing to 0.05 units/kg/hour' mean in practice?

When glucose falls below 14 mmol/L you add 10% glucose at 125 ml/hour and may halve the insulin rate. JBDS words it as a consideration, so the decision depends on whether the ketone and bicarbonate targets are still being met.

Which DKA patients need a higher level of care?

JBDS asks for more cautious fluid replacement, with high dependency care or a central line considered, in those aged 18 to 25, the elderly, pregnant women, and people with heart or renal failure. A systolic below 90 despite boluses or a reduced conscious level also warrants critical care involvement.

Should the patient's usual insulin continue?

Long-acting analogues such as glargine, detemir and degludec continue at the usual dose and time throughout the fixed rate infusion. Short-acting insulin is restarted at the switch, with the intravenous infusion stopped 30 minutes after the first subcutaneous dose.

Diabetic Ketoacidosis — CT1 Anaesthetics Interview Clinical Judgement Answer

Q: When is DKA resolved?

When ketones are below 0.6 mmol/L and venous pH is above 7.3. JBDS says not to use bicarbonate as the marker at 6 hours, and expects resolution by 24 hours; if it has not happened, senior and specialist input is needed.

Diabetic ketoacidosis is diagnosed when all three of the following are present: capillary glucose above 11 mmol/L or known diabetes, ketones above 3 mmol/L, and venous pH below 7.3 or bicarbonate below 15 mmol/L. According to the Joint British Diabetes Societies pathway, revised March 2023, treatment is 0.9% sodium chloride first, a fixed rate insulin infusion at 0.1 units/kg/hour, and potassium replaced by band. At the CT1 anaesthetics interview the marks are for that order, the monitoring, and knowing when you would call.

Key takeaways

Diagnosis needs all three: glucose above 11 mmol/L or known diabetes, ketones above 3 mmol/L, and pH below 7.3 or bicarbonate below 15 mmol/L (JBDS, March 2023)
Fluid comes first: 1 litre of 0.9% sodium chloride over the first hour if systolic is 90 mmHg or above; 500 ml over 10 to 15 minutes, repeated, if it is below
Fixed rate insulin is 0.1 units/kg/hour, and the patient's long-acting insulin analogue continues at the usual dose and time
Potassium: none if above 5.5 mmol/L, 40 mmol per litre if 3.5 to 5.5, senior review and extra potassium if below 3.5
Add 10% glucose at 125 ml/hour when glucose falls below 14 mmol/L, and consider reducing insulin to 0.05 units/kg/hour
Resolution is ketones below 0.6 mmol/L and venous pH above 7.3, expected by 24 hours

How do you recognise diabetic ketoacidosis?

Diabetic ketoacidosis is recognised by its triad, and the JBDS pathway insists all three parts are present. Glucose above 11 mmol/L or known diabetes, blood ketones above 3 mmol/L or urine ketones of two plus or more, and venous pH below 7.3 or bicarbonate below 15 mmol/L.

The glucose clause matters. According to JBDS, DKA can occur with a near-normal glucose in people on SGLT2 inhibitors, so a known diabetic with ketones and acidosis still counts. Say that, and say the drug should be stopped.

In practice the patient is vomiting, dehydrated, breathing deeply and drowsy. That said, the diagnosis is made on the numbers, so the first investigation is a capillary glucose, a capillary ketone and a venous gas.

What do you do in the first hour?

In the first hour of DKA you start fluid through a large-bore cannula on a pump, start the fixed rate insulin infusion, and assess the patient. JBDS sets time zero as the moment intravenous fluid begins.

Fluid: 0.9% sodium chloride at the rate set by the systolic blood pressure, below
Insulin: 50 units of human soluble insulin in 50 ml of 0.9% sodium chloride at 0.1 units/kg/hour on an estimated weight
Assessment: respiratory rate, temperature, blood pressure, pulse, saturations, Glasgow Coma Scale and a full examination
Investigations: laboratory glucose, venous gas, urea and electrolytes, full blood count, blood cultures, ECG, chest radiograph and urine
Monitoring: hourly capillary glucose and ketones, venous bicarbonate and potassium at 60 minutes and 2 hours, then 2-hourly
Precipitant: look for and treat it, most often infection or missed insulin

If intravenous access cannot be obtained, JBDS says to request critical care support immediately. For an anaesthetic CT1 that is the moment your skills are the reason you are called.

How much fluid, and how fast?

The DKA fluid rate depends on the systolic blood pressure at presentation, because restoring circulating volume is the priority. JBDS gives two starting points.

If the systolic is below 90 mmHg, give 500 ml of 0.9% sodium chloride over 10 to 15 minutes and repeat it while awaiting senior input. Most people need 500 to 1,000 ml given rapidly. Consider involving critical care. Once the systolic is above 90, give 1 litre over the next hour.

If the systolic is 90 mmHg or above, give 1 litre over the first hour. Then 1 litre with potassium chloride over 2 hours, another over 2 hours, one over 4 hours, one over 4 hours and one over 6 hours, reassessing at each bag.

However, the pathway asks for more cautious replacement in young people aged 18 to 25, the elderly, pregnancy, and heart or renal failure, with a high dependency bed or central line considered. Saying who you slow down for is a mark.

When does insulin start, and at what rate?

Fixed rate intravenous insulin in DKA starts in the first hour at 0.1 units/kg/hour, alongside the fluid rather than before it. JBDS describes 50 units of human soluble insulin made up to 50 ml with 0.9% sodium chloride.

If the patient normally takes a long-acting analogue such as glargine, detemir or degludec, it continues at the usual dose and time. Stopping it is a common error, and it makes the later switch to subcutaneous insulin harder.

When the glucose falls below 14 mmol/L, add 10% glucose at 125 ml/hour and keep the insulin running to clear the ketones. JBDS says to consider reducing the rate to 0.05 units/kg/hour at that point, which is a consideration rather than a rule.

How is potassium replaced?

Potassium in DKA is replaced by the serum band, and the whole-body deficit is large even when the first level is high. JBDS gives three bands for the potassium added to each litre of fluid.

Above 5.5 mmol/L: no potassium in the fluid, recheck
3.5 to 5.5 mmol/L: 40 mmol of potassium chloride per litre
Below 3.5 mmol/L: senior review, because additional potassium is required

Potassium is checked at 60 minutes, 2 hours and then 2-hourly, with continuous cardiac monitoring if it is abnormal. If it is still outside the normal range after a further hour, JBDS says to seek immediate senior medical advice.

What are the targets, and what if they are missed?

The DKA treatment targets from 60 minutes to 6 hours are a ketone fall of at least 0.5 mmol/L per hour, a bicarbonate rise of at least 3 mmol/L per hour, and a glucose fall of at least 3 mmol/L per hour. Hypoglycaemia is avoided and potassium is kept in range.

If the targets are missed, first check that the pump is working and connected and that the residual insulin volume is correct. If the equipment is fine, JBDS says to increase the infusion by 1 unit per hour each hour until the targets are met.

Alongside this run the additional measures: NEWS2 observations, a fluid balance chart aiming for at least 0.5 ml/kg/hour of urine, a catheter if no urine by 60 minutes, a nasogastric tube with airway protection if obtunded or vomiting, an arterial gas and repeat chest film if saturations are below 92%, and low molecular weight heparin thromboprophylaxis.

When is DKA resolved, and how do you switch to subcutaneous insulin?

DKA is resolved when ketones are below 0.6 mmol/L and venous pH is above 7.3, and JBDS expects the ketonaemia and acidosis to have cleared by 24 hours. Bicarbonate is not used as the marker at 6 hours because the chloride load from saline lowers it.

Convert to subcutaneous insulin when the patient is biochemically stable and ready to eat, managed by the specialist diabetes team. Do not stop the intravenous insulin until 30 minutes after the subcutaneous short-acting dose has been given.

If ketones have cleared but the patient is not eating, move to a variable rate infusion under local guidance. A newly diagnosed patient must be seen by the specialist team before discharge.

When do you call for help?

You call for help in DKA at the start, not when things go wrong, and the JBDS pathway names the triggers. A systolic below 90 despite fluid, no intravenous access, a reduced conscious level, a potassium outside range after an hour, or targets not met by 6 hours all need senior or critical care input.

For the anaesthetic CT1 the specific reasons are airway protection in an obtunded vomiting patient, central access, and the high dependency bed the pathway asks you to consider in the frail, the pregnant and those with heart or renal failure.

Those aged 16 to 18 managed by paediatric teams follow the BSPED guideline, not the adult one. It is a one-line fact that shows you know where the adult pathway stops.

Which traps catch candidates?

The DKA traps at interview are the ones the JBDS text was written to close. Starting insulin before fluid, stopping the long-acting analogue, treating the glucose rather than the ketones, and adding potassium to a litre when the level is above 5.5.

Quoting a bicarbonate-based endpoint at 6 hours: the pathway says ketones and pH
Giving a fixed 500 ml bolus regardless of blood pressure: the 500 ml rapid bolus is for a systolic below 90
Missing euglycaemic DKA in a patient on an SGLT2 inhibitor
Stopping the insulin infusion as soon as the subcutaneous dose is written up rather than 30 minutes after it is given

What is the interviewer listening for?

In a DKA scenario the assessors are listening for an ordered plan with numbers, a monitoring schedule, and a named point at which you escalate. They are not listening for pathophysiology.

The three diagnostic criteria, with the values
Fluid before insulin, and the rate set by the systolic pressure
0.1 units/kg/hour, the analogue continued, and glucose added below 14 mmol/L
Potassium by band, checked 2-hourly
Who you call, and what would make you call sooner

How this comes up at the CT1 anaesthetics interview

DKA appears in the clinical judgement station as a ward or emergency department referral: a young patient with type 1 diabetes, vomiting and drowsy, and the question is what you do in the first hour. The station is one of two 15-minute stations, each marked out of 50, with an appointable score of 60 out of 100.

The follow-up usually tests a decision under pressure: the pump alarms, the potassium comes back at 3.1, or the patient will not protect their airway. anaestheticinterview's bank of 340 questions includes a scored DKA scenario with AI-marked spoken practice, so the numbers above can be said out loud until they are automatic.

Diabetic Ketoacidosis