DKA: Fluids, Insulin, Potassium & Phosphate — No-Overcorrection Protocol

Diabetic ketoacidosis (DKA) is shock physiology plus metabolic chaos. The cure is boring on purpose: fluids → potassium → insulin → dextrose, with frequent labs and thoughtful de-escalation. This protocol keeps patients safe while the biochemistry catches up.

The Diagnostic Triad

• Hyperglycemia (commonly >250 mg/dL; euglycemic DKA can occur with SGLT2 inhibitors).
• Ketosis (serum β-hydroxybutyrate elevated; urine ketones can lag or underestimate severity).
• Metabolic acidosis (pH <7.3 and/or HCO₃⁻ <18 mEq/L) with anion gap elevation.

Check precipitating causes: missed insulin, infection, MI, stroke, pancreatitis, steroids, pregnancy, SGLT2s, alcohol, GI illness.

Initial Assessment (first 10 minutes)

• Vitals, mental status, volume status (dry mucosa, tachycardia, hypotension), Kussmaul respirations.
• POCUS: IVC, bladder, lung B-lines if volume concerns.
• Labs: BMP (with Mg/Phos), VBG/ABG, β-hydroxybutyrate (if available), CBC, lactate, UA/urine ketones, pregnancy test, cultures if infection suspected.
• ECG for exposure of K⁺ derangements and ischemia.

Step 1 — Fluids (fix the tank)

• Balanced crystalloids (e.g., LR or Plasma-Lyte) initial bolus 1 L over the first hour (adjust for shock, CHF, CKD, elderly).
• Then 250–500 mL/h guided by perfusion, urine output, and bedside ultrasound. Goal is steady correction without pulmonary edema.
• Switch to D5-containing fluids later when glucose approaches ~200 mg/dL (11 mmol/L), while the anion gap is still open.

Step 2 — Potassium (before insulin)

• K⁺ <3.3 mEq/L: hold insulin and give KCl (e.g., 20–30 mEq/h IV, central line allows faster) until K⁺ ≥3.3.
• K⁺ 3.3–5.2: add 20–30 mEq K⁺ per liter of IV fluid to keep K⁺ 4–5.
• K⁺ >5.2: withhold K⁺ initially, recheck every 2 h.
• Magnesium repletion (e.g., 2 g IV) if low—helps retain K⁺ and lowers arrhythmia risk.

Step 3 — Insulin (after K⁺ is safe)

• IV regular insulin 0.1 units/kg bolus then 0.1 units/kg/h infusion, or skip the bolus and start 0.14 units/kg/h infusion directly—both are acceptable approaches.
• Target glucose fall of ~50–75 mg/dL per hour. If not achieved, small rate uptitrations are reasonable.
• When glucose reaches ~200 mg/dL, add D5 (e.g., D5-LR) and drop insulin to ~0.02–0.05 units/kg/h to continue clearing ketones/closing the gap.

Step 4 — Bicarbonate?

• Not routine. Consider only for pH ≤6.9 with hemodynamic compromise, severe hyperkalemia, or life-threatening acidosis per local protocol, recognizing limited evidence and potential downsides (hypokalemia, paradoxical CNS acidosis).

Step 5 — Phosphate?

• DKA shifts phosphate intracellularly during treatment; routine replacement is not required.
• Replete if phosphate <1.0 mg/dL (0.32 mmol/L), significant hemolysis risk, respiratory muscle weakness, or cardiomyopathy; use K-phos if potassium is low/normal.

Monitoring Cadence

• Glucose hourly until stable trend.
• Electrolytes (Na⁺, K⁺, HCO₃⁻), anion gap, venous pH, phosphate, magnesium every 2–4 hours depending on severity.
• Input/output, mental status, and signs of fluid overload each nursing check.

When Is DKA “Resolved”?

• Glucose <200 mg/dL and two of the following:
  • HCO₃⁻ ≥15 mEq/L
  • pH ≥7.3
  • Anion gap closed (local definition; often ≤12)
• β-hydroxybutyrate normalization (if available) supports resolution.

Transition to Subcutaneous Insulin (don’t miss the overlap)

• Calculate total daily dose (TDD) ~0.5–0.7 units/kg/day (individualize: lower in insulin-sensitive, higher if obese/steroid use).
• Give basal insulin (e.g., glargine) 2 hours before stopping IV insulin to avoid rebound ketosis.
• Prandial/correctional insulin starts when eating; carbohydrate-consistent diet and diabetes education before discharge.

Sodium & Osmolality Notes

• Calculate corrected Na⁺ for hyperglycemia: add ~1.6 mEq/L to measured Na⁺ for every 100 mg/dL glucose above 100 (some use 2.4 at higher ranges).
• Avoid rapid effective osmolality shifts; steady trajectories lower cerebral edema risk.

Pediatrics & Cerebral Edema Risk (awareness)

• Children are at higher risk; use weight-based, slower fluid strategies and pediatric-specific protocols.
• Headache, bradycardia, altered mental status → urgent escalation; consider hypertonic saline per pediatric guidance.

Special Situations

• Euglycemic DKA (SGLT2-associated): glucose may be <250 mg/dL; prioritize ketone clearance with insulin and add dextrose earlier.
• Pregnancy: tighter targets, lower threshold to admit/ICU; involve obstetrics early.
• Renal/cardiac failure: cautious fluids, invasive monitoring where appropriate, earlier ICU involvement.

Common Pitfalls

• Starting insulin when K⁺ <3.3.
• Failing to add D5 when glucose hits ~200 mg/dL—ketosis won’t clear if you stop insulin too early.
• No overlap between IV and basal insulin at transition.
• Under-resuscitating, then over-correcting later—aim for steady, not flashy.

Patient FAQs

“Why do I keep getting sugar water when my glucose is high?” Dextrose lets us continue insulin to clear ketones safely once glucose falls—insulin treats the DKA, not just the sugar number.

“Can I go back on my SGLT2 right away?” Not until your team confirms the cause is addressed and the risk of euglycemic DKA is low; many patients stop temporarily.

References & Notes

Pragmatic DKA protocol: fluids first, potassium before insulin if low, weight-based IV insulin with dextrose when ~200 mg/dL, cautious electrolyte replacement, and overlapping basal insulin at transition. Local protocols vary—follow institutional guidance. Educational only.