USMLE Prep - Medical Reference Library

Diabetic Ketoacidosis - Sick Day Rules and Outpatient Prevention

System: Metabolic Medicine • Reviewed: Aug 31, 2025 • Step 1Step 2Step 3

Synopsis:

Teach sick day plans with hydration, supplemental insulin, ketone testing, and early contact to prevent progression to DKA and hospitalization.

Key Points

  • Stabilize ABCs; begin targeted evaluation without delaying life-saving therapy.
  • Use system-specific risk tools to guide testing and disposition.
  • Order high-yield tests first; escalate imaging when indicated.
  • Start evidence-based initial therapy and reassess frequently.

Algorithm

  1. Primary survey and vitals; IV access and monitors.
  2. Focused history/physical; identify red flags and likely etiologies.
  3. Order system-appropriate labs and imaging (see Investigations).
  4. Initiate guideline-based empiric therapy (see Pharmacology).
  5. Reassess response; arrange consultation and definitive management.

Clinical Synopsis & Reasoning

DKA is precipitated by insulin deficiency and counter‑regulatory surge, producing hyperglycemia, ketonemia, and anion‑gap acidosis. Confirm diagnosis with glucose, β‑hydroxybutyrate/ketones, pH, and bicarbonate; assess volume depletion and precipitating factors (infection, insulin omission, MI, stroke). Expect total body potassium deficit despite initial normal/elevated K⁺. Frequent bedside reassessment and point‑of‑care tests are critical to guide safe correction and detect cerebral edema risk.


Treatment Strategy & Disposition

Resuscitate with balanced crystalloids, begin insulin infusion after verifying K⁺ ≥3.3 mEq/L, and replace electrolytes proactively, especially potassium and phosphate as indicated. Once glucose reaches ~200–250 mg/dL with persistent ketosis, add dextrose to avoid hypoglycemia while clearing ketones; transition to basal‑bolus when anion gap closes and patient can eat. Treat precipitants (e.g., antibiotics for infection) and provide sick‑day education. ICU admission for severe acidosis, altered mental status, or need for continuous insulin/electrolyte titration; otherwise step‑down with protocolized monitoring.


Epidemiology / Risk Factors

  • Risk factors vary by condition and patient profile

Investigations

TestRole / RationaleTypical FindingsNotes
CBCBaseline hematologyAbnormal counts
BMPElectrolytes/renalDerangements

Call or Seek Care When

SituationConcern
Vomiting and cannot keep fluidsDehydration risk
Moderate or large ketonesImpending DKA
Glucose remains very high despite insulinNeed for evaluation

Pharmacology

MedicationMechanismOnsetRole in TherapyLimitations
Sodium bicarbonateBufferHoursSevere acidemia (pH ≤6.9)Alkalemia, hypokalemia; outpatient use
Isotonic fluidsVolume expansionImmediateRestore perfusion and osmolar balanceFluid overload in CHF/CKD; outpatient use
Potassium chlorideElectrolyte repletionHoursPrevent hypokalemiaOvercorrection arrhythmia; outpatient use
Regular insulin (IV)Anabolic/anti-ketoticMinutesCorrect hyperglycemia/ketosisHypoglycemia, hypokalemia; outpatient use
Phosphate (select cases)Electrolyte repletionHoursSevere depletionHypocalcemia; outpatient use

Prognosis / Complications

  • Prognosis depends on severity, comorbidities, and timeliness of care

Patient Education / Counseling

  • Explain red flags and when to seek emergent care.
  • Reinforce medication adherence and follow-up plan.

Notes

Ensure access to strips or sensors and ketone testing. Educate on insulin pump and CGM troubleshooting if used.


References

  1. ADA diabetes sick day guidance — Link
  2. Endocrine society outpatient diabetes management — Link