Fluid Selection in Severe DKA Based on Blood Glucose
In severe diabetic ketoacidosis, start with 0.9% normal saline (isotonic saline) at 15-20 mL/kg/h for the first hour regardless of the initial blood glucose level, then switch fluid type based on corrected serum sodium and glucose levels—not the random blood glucose alone.
Initial Resuscitation (First Hour)
All patients with severe DKA require aggressive volume expansion with 0.9% NaCl (isotonic saline) at 15-20 mL/kg/h (approximately 1-1.5 liters in average adults) during the first hour, unless cardiac compromise is present 1, 2, 3, 4, 3. This recommendation is uniform across all major guidelines and does not vary based on the presenting glucose level.
Subsequent Fluid Selection Algorithm
After the initial hour of resuscitation, fluid choice depends on corrected serum sodium (not random blood glucose):
Calculate Corrected Sodium
Choose Maintenance Fluid Based on Corrected Sodium
If corrected sodium is normal or elevated: Use 0.45% NaCl (half-normal saline) at 4-14 mL/kg/h 2, 3
If corrected sodium is low: Continue 0.9% NaCl at 4-14 mL/kg/h 2, 3
When Glucose Falls Below 250 mg/dL (14 mmol/L)
This is the critical glucose-dependent fluid change:
- Add 5-10% dextrose to the current saline solution (either 0.45% or 0.9% NaCl based on sodium status) 1, 3, 1
- Continue the fixed-rate insulin infusion to clear ketones—do not reduce insulin just because glucose is falling 1, 5, 6
- The most recent ADA 2025 guidelines specifically state to add dextrose alongside continued 0.9% NaCl/crystalloid when glucose approaches target range 1
Critical Nuances and Common Pitfalls
Pitfall #1: Stopping or reducing insulin when glucose normalizes The glucose will fall faster than ketones clear. You must continue adequate insulin (with dextrose supplementation) until ketosis resolves, which may take significantly longer than glucose normalization 5, 6. One case report documented requiring 5 days of high-dose insulin (8-14 U/h) with 10-20% glucose to resolve severe DKA 6.
Pitfall #2: Using initial glucose level to guide fluid type The initial random blood glucose is irrelevant for fluid selection. What matters is the corrected sodium and the subsequent glucose trajectory during treatment 2, 3.
Pitfall #3: Inadequate potassium replacement Once renal function is confirmed (urine output ≥0.5 mL/kg/h), add 20-30 mEq/L potassium (2/3 KCl and 1/3 KPO4) to all IV fluids 2, 3. Hypokalaemia occurs in approximately 50% of DKA cases during treatment and severe hypokalaemia (<2.5 mEq/L) increases mortality 7.
Pitfall #4: Overly rapid osmolality correction The induced change in serum osmolality should not exceed 3 mOsm/kg/h to avoid cerebral edema, particularly in pediatric patients but also relevant in adults 2, 3.
Target Glucose During DKA Treatment
- For DKA: Maintain glucose between 150-200 mg/dL until resolution 1
- For HHS: Target glucose between 200-250 mg/dL until resolution 1
Monitoring Requirements
Check electrolytes, renal function, venous pH, osmolality, and glucose every 2-4 hours until stable 1. The 2025 ADA guidelines emphasize using bedside capillary blood ketone monitoring when available as the preferred method to assess treatment response 1, 5.
Special Consideration: Balanced Crystalloids
While the 2025 ADA guidelines mention "0.9% NaCl or other crystalloid" 1, suggesting openness to buffered solutions like Plasma-Lyte 148, there is currently insufficient evidence to recommend them over normal saline. An ongoing trial (BEST-DKA) is comparing these options 8, but until results are available, 0.9% NaCl remains the standard of care for initial resuscitation.