Diabetic Ketoacidosis Management
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Direct answer
Rehydration does most of the life-saving in diabetic ketoacidosis, with insulin given as a continuous low-dose infusion and potassium corrected in parallel. The diagnostic triad is hyperglycaemia (usually above 250 mg/dL), ketonaemia or ketonuria (beta-hydroxybutyrate of 3 mmol/L or more), and metabolic acidosis — pH below 7.30 or bicarbonate under 18 mmol/L. Isotonic saline 15–20 mL/kg in the first hour restores perfusion; insulin starts at 0.1 units/kg/hour only after potassium is confirmed above 3.3 mmol/L; dextrose is added and the insulin rate reduced once glucose falls under 200 mg/dL. Resolution is judged by the anion gap, not the glucose, and subcutaneous basal insulin must overlap the infusion by one to two hours to prevent rebound ketosis. In children, cerebral oedema remains the principal cause of death and demands mannitol or hypertonic saline the moment it is suspected.
What you must remember
- Trigger hunt before treatment ends: infection is the commonest precipitant in India; missed insulin (especially in T1DM adolescents), myocardial infarction, surgery, new-onset diabetes and drugs (steroids, SGLT2 inhibitors) follow — an unexplained DKA is an unfinished DKA.
- Fluid plan: 0.9 per cent saline 15–20 mL/kg over the first hour, then reassess corrected sodium — if normal or high, switch to 0.45 per cent; replace the estimated deficit evenly over 24–48 hours.
- Insulin plan: 0.1 units/kg/hour IV with no bolus needed when perfusion is adequate; when glucose reaches 200 mg/dL, add dextrose 5–10 per cent and cut the infusion to 0.02–0.05 units/kg/hour — insulin is continued until ketoacidosis clears, only the glucose target moves.
- Potassium rule of threes: below 3.3 mmol/L — replace first and hold insulin; 3.3–5.2 — add 20–30 mmol/L to fluids; above 5.2 with urine output — check hourly and start later.
- Bicarbonate: only for pH below 6.9, with potassium in the bottle; routine use worsens cerebral oedema and hypokalaemia — a recurring exam negative-mark.
- Cerebral oedema signs: headache, irritability, bradycardia with hypertension, falling Glasgow score — treat before imaging with mannitol 0.5–1 g/kg or 3 per cent saline 2.5–5 mL/kg; gradual fluid correction in children is the only proven prevention.
- Capillary beta-hydroxybutyrate beats urine ketones: nitroprusside strips detect acetoacetate, which may rise during recovery as beta-hydroxybutyrate is converted — a "worsening" urine test in a clinically improving patient is chemistry, not deterioration.
- Euglycaemic DKA: SGLT2 inhibitors, pregnancy and partial treatment present with glucose under 250 mg/dL — ketones make the diagnosis, so check them in every acidotic diabetic regardless of sugar.
The first four hours, hour by hour
A 17-year-old arrives drowsy, breathing deeply at 28 per minute, glucose 468 mg/dL, pH 7.08, bicarbonate 7, ketones 5.8 mmol/L, potassium 3.1. Hour zero: two IV lines, 1 L saline over the hour, and potassium 20 mmol in the next bag — insulin waits because potassium below 3.3 mmol/L plus insulin-driven potassium entry risks arrhythmia. Hour one: start insulin 6 units/hour (0.1/kg), continue saline, hourly ketone and potassium checks. Hour two: glucose 320, potassium 3.6 with replacement, ketones 4.1 — no dextrose yet, aiming for a glucose fall of 50–75 mg/dL/hour. Hour three: glucose touches 200 — add 5 per cent dextrose, halve the insulin to 3 units/hour, keep saline running. Hour four: pH 7.24, ketones 1.8, anion gap closing; basal analogue glargine is given subcutaneously now so that when the infusion stops, cover already exists — overlap of one to two hours is the standard. Transition to subcutaneous basal-bolus only when the gap is under 12, the pH exceeds 7.3 and the patient eats; before discharge, the education questions are why it happened and how sick-day rules were missed.
How the exam frames it
Stems test sequencing, not memory: potassium 2.9 with ketoacidosis — what is withheld and given first? The answer (insulin withheld, potassium replaced) separates pass from distinction. A second format is the recovering patient whose urine ketones worsen — candidates who escalate insulin fail the stem; those who know acetoacetate conversion hold the line. The third is the child with headache and bradycardia mid-treatment — the diagnosis and drug (mannitol or 3 per cent saline, immediately, before CT) must be reflexive. Indian series report cerebral oedema and delayed presentation as the dominant contributors to paediatric DKA mortality, which is why fluid discipline in children earns disproportionate viva weight.
Frequently asked questions
At what potassium level is insulin withheld in DKA?
Below 3.3 mmol/L — potassium is replaced first, because insulin drives potassium intracellularly and can precipitate fatal arrhythmia in a depleted patient.
Why does the anion gap, not glucose, define resolution?
Ketoacid clearance is the disease; glucose falls faster with fluids alone, and stopping insulin at normoglycaemia leaves ketogenesis untreated and invites relapse.
When is bicarbonate indicated in DKA?
Only when arterial pH is below 6.9 — given slowly with potassium; above that threshold it increases cerebral oedema and does not improve outcomes.
How is transition to subcutaneous insulin performed?
Once the anion gap closes, pH exceeds 7.3 and the patient can eat: give basal analogue and overlap the IV infusion for one to two hours before stopping it.
What is euglycaemic diabetic ketoacidosis?
Ketoacidosis with glucose below 250 mg/dL, classically with SGLT2 inhibitors, pregnancy or reduced oral intake — diagnosed by ketones and acidosis despite unremarkable sugar.