Fluid and electrolyte management in diabetes

Red Flags

DKA: glucose >250, ketones positive, pH <7.3, HCO₃ <15 — ICU/HDU; isotonic crystalloid then half-saline; insulin infusion; potassium replacement once K+ <5.5^[1]
HHS: glucose >600, osmolality >320, minimal ketones — slow glucose correction (<3 mmol/L/h); cautious sodium replacement; thrombosis prophylaxis^[1]
Severe hyperkalaemia (K+ ≥6.5 with ECG changes) on RAAS blockade or SGLT2 — emergency potassium-lowering bundle; pause culprits^[1]
Severe hyponatraemia (Na+ <125 with confusion, seizures) — slow correction (≤8–10 mmol/L/24h); avoid central pontine myelinolysis^[1]

First-line treatment

Interventions

Sick-day rules^[1]
Continue insulin and metformin during illness unless dehydrated; pause SGLT2 inhibitor with vomiting or dehydration; check glucose more frequently; ketone testing if T1DM with glucose >250 OR T2DM on SGLT2 with symptoms
DKA/HHS resolution criteria^[1]
DKA: pH ≥7.3, HCO₃ ≥15, anion gap ≤12. HHS: osmolality <315, mental status restored, eating. Transition to SC insulin with ≥1 hour overlap before stopping infusion

First-line drug therapy

Drug	Class	Adult	Paediatric	Notes
0.9% sodium chloride or balanced crystalloid (DKA initial)^[1]	Isotonic crystalloid	1 L over 1 hour, then 1 L over 2 h, then per response (typically 250–500 mL/h × 4 h, then 125–250 mL/h)	10–20 mL/kg bolus, max 50 mL/kg in first 4 h	Switch to 0.45% saline once corrected sodium normalises and glucose drops; balanced crystalloid (Plasmalyte) reduces hyperchloraemic acidosis
IV insulin infusion (DKA/HHS)^[1]	Continuous IV regular insulin	0.1 U/kg/h (may start with 0.1 U/kg bolus); titrate to glucose fall of 50–75 mg/dL/hr; add dextrose to fluids when glucose <250	0.05–0.1 U/kg/h	Continue until ketones cleared, anion gap closed, and patient eating; transition to subcutaneous basal-bolus with overlap
Potassium replacement^[1]	Electrolyte	Add 20–40 mEq KCl/L to maintenance fluids once K+ <5.5; hold insulin if K+ <3.3 until replaced	Per weight per paediatric DKA protocol	DKA insulin drives K+ into cells; pre-existing total-body K+ depletion despite normal serum value
Hypertonic saline (severe symptomatic hyponatraemia)^[1]	Osmotic correction	3% saline 100 mL bolus over 10 min, repeat to maximum 300 mL or 4–6 mmol/L Na+ rise; cap correction <10 mmol/L per 24 h	—	Symptomatic hyponatraemia (seizures, coma); specialist supervision; avoid overcorrection (osmotic demyelination risk)

0.9% sodium chloride or balanced crystalloid (DKA initial)^[1]

Isotonic crystalloid

Adult: 1 L over 1 hour, then 1 L over 2 h, then per response (typically 250–500 mL/h × 4 h, then 125–250 mL/h)
Paediatric: 10–20 mL/kg bolus, max 50 mL/kg in first 4 h

Switch to 0.45% saline once corrected sodium normalises and glucose drops; balanced crystalloid (Plasmalyte) reduces hyperchloraemic acidosis

IV insulin infusion (DKA/HHS)^[1]

Continuous IV regular insulin

Adult: 0.1 U/kg/h (may start with 0.1 U/kg bolus); titrate to glucose fall of 50–75 mg/dL/hr; add dextrose to fluids when glucose <250
Paediatric: 0.05–0.1 U/kg/h

Continue until ketones cleared, anion gap closed, and patient eating; transition to subcutaneous basal-bolus with overlap

Potassium replacement^[1]

Electrolyte

Adult: Add 20–40 mEq KCl/L to maintenance fluids once K+ <5.5; hold insulin if K+ <3.3 until replaced
Paediatric: Per weight per paediatric DKA protocol

DKA insulin drives K+ into cells; pre-existing total-body K+ depletion despite normal serum value

Hypertonic saline (severe symptomatic hyponatraemia)^[1]

Osmotic correction

Adult: 3% saline 100 mL bolus over 10 min, repeat to maximum 300 mL or 4–6 mmol/L Na+ rise; cap correction <10 mmol/L per 24 h
Paediatric: —

Symptomatic hyponatraemia (seizures, coma); specialist supervision; avoid overcorrection (osmotic demyelination risk)

Safety-net

If you are vomiting or have severe diarrhoea, pause SGLT2 inhibitor and contact your clinician same day — risk of euglycaemic DKA^[1]
Drink fluids freely during illness if able; if unable to keep fluids down, seek urgent care^[1]
Severe nausea, abdominal pain, breathlessness, or confusion — call emergency services (could be DKA or HHS)^[1]

Referral criteria

DKA, HHS, or severe hyperkalaemiaICU/HDU for IV insulin infusion, fluid resuscitation, electrolyte management^[1]
Severe hyponatraemia (Na+ <125) or hypernatraemia (Na+ >155)Hospital admission for cautious correction with monitoring^[1]
Recurrent DKA / HHS despite appropriate sick-day educationDiabetes specialist for adherence and regimen review^[1]

Clinical summary

Peri-operative and acute-illness fluid and electrolyte management in adults with diabetes — DKA/HHS resuscitation, sick-day rules, dysnatraemia and hyperkalaemia.

References

1.RSSDI Consensus on Fluid, Electrolytes & Energy Management in Diabetes (2025) (2025)