10.1 DKA and HHS Management Protocols
Key Takeaways
DKA requires glucose ≥200 mg/dL or a history of diabetes, beta-hydroxybutyrate ≥3.0 mmol/L (or urine ketones ≥2+), and pH <7.30 and/or bicarbonate <18 mEq/L. HHS requires glucose ≥600 mg/dL, effective osmolality >300 or total osmolality >320 mOsm/kg, beta-hydroxybutyrate <3.0 mmol/L, pH ≥7.30 and bicarbonate ≥15 mEq/L.
Start isotonic saline or balanced crystalloid at 500–1,000 mL/hr for the first 2–4 hours in adults without cardiac/renal compromise; use smaller reassessed boluses when overload risk is high. Adjust fluids to perfusion, balance, sodium and osmolality; corrected sodium alone does not mandate half-normal saline.
If potassium is <3.5 mEq/L, begin IV potassium replacement and delay insulin until potassium is >3.5 mEq/L. Once potassium falls below 5.0 mEq/L, replace it to maintain 4–5 mEq/L, adjusting for renal function and repeated measurements.
Use IV regular insulin 0.1 units/kg/hr for DKA or mixed DKA/HHS. HHS with beta-hydroxybutyrate <3.0 mmol/L, pH ≥7.30 and bicarbonate ≥18 mEq/L uses 0.05 units/kg/hr. When glucose falls below 250 mg/dL, add 5–10% dextrose; reduce the DKA infusion to 0.05 units/kg/hr and continue until ketoacidosis resolves.
DKA resolves when plasma beta-hydroxybutyrate is <0.6 mmol/L plus either venous pH ≥7.30 or bicarbonate ≥18 mEq/L; glucose should ideally be <200 mg/dL. Do not use anion-gap closure alone. Give basal insulin before stopping IV insulin, with at least 1–2 hours of overlap; a 2–4-hour overlap is appropriate for many basal-insulin protocols.
10.1 DKA and HHS Management Protocols
Clinical Scenario: A 24-year-old female with type 1 diabetes presents with nausea, vomiting, and abdominal pain. Exam reveals lethargy, Kussmaul breathing, fruity breath, and dehydration. Vital signs: BP 92/54 mmHg, HR 128 bpm, RR 32, temp 37.2°C, SpO2 98%. Point-of-care glucose is > 500 mg/dL. Initial labs: glucose 542 mg/dL, arterial pH 7.14, PaCO2 21 mmHg, bicarbonate 8 mEq/L, sodium 131 mEq/L, potassium 5.6 mEq/L, chloride 95 mEq/L, beta-hydroxybutyrate 6.8 mmol/L, and anion gap 28 mEq/L.
Pathophysiologic Divergence: DKA vs. HHS
Diabetic Ketoacidosis (DKA) and Hyperosmolar Hyperglycemic State (HHS) represent opposite poles of acute hyperglycemic crises:
- Diabetic Ketoacidosis (DKA): Driven by absolute insulin deficiency and counter-regulatory hormone excess (glucagon, catecholamines, cortisol). Unopposed lipolysis releases free fatty acids into portal circulation; hepatic beta-oxidation generates acetoacetate and beta-hydroxybutyrate, creating a high anion gap metabolic acidosis.
- Hyperosmolar Hyperglycemic State (HHS): Driven by relative insulin deficiency and severe dehydration in type 2 diabetes. Residual portal insulin suppresses lipolysis and ketogenesis, averting ketoacidosis. However, it cannot prevent hepatic gluconeogenesis. Unchecked hyperglycemia causes osmotic diuresis, generating massive water deficits (8–12 L in HHS vs. 4–6 L in DKA) and hyperosmolality.
Diagnostic Comparison Matrix
| Diagnostic Parameter | Mild DKA | Moderate DKA | Severe DKA | HHS |
|---|---|---|---|---|
| Glucose / Diabetes | ≥200 mg/dL or prior diabetes | ≥200 mg/dL or prior diabetes | ≥200 mg/dL or prior diabetes | Glucose ≥600 mg/dL |
| pH / Bicarbonate | pH >7.25 to <7.30 or HCO3 15–18 mEq/L | pH 7.00–7.25 or HCO3 10 to <15 | pH <7.00 or HCO3 <10 | pH ≥7.30 and HCO3 ≥15 |
| Beta-Hydroxybutyrate | 3.0–6.0 mmol/L | 3.0–6.0 mmol/L | >6.0 mmol/L | <3.0 mmol/L |
| Osmolality | Variable | Variable | Variable | Effective >300 or total >320 mOsm/kg |
| Mental Status | Alert | Alert / drowsy | Stupor / coma | Variable; coma is not required |
DKA requires all three diagnostic components: diabetes/hyperglycemia, ketosis and metabolic acidosis. Use the most severe relevant features to guide care; not every severity variable must be present. HHS requires all four criteria above. Overlap is common; substantial ketosis or acidosis with hyperosmolality requires management as mixed DKA/HHS. Total osmolality adds BUN/2.8 to the effective-osmolality formula when BUN is in mg/dL.
Note
Key Formulas:
- Effective Serum Osmolality (): . Urea freely diffuses across membranes and is omitted.
- Serum Anion Gap: . Normal is mEq/L. Serum beta-hydroxybutyrate is the definitive ketosis biomarker; nitroprusside tests measure only acetoacetate.
Fluid Resuscitation Sequence
Fluid resuscitation takes precedence in initial stabilization, restoring renal perfusion and lowering glucose by up to 100 mg/dL/hr through glycosuria:
- Initial Expansion: Start 0.9% saline or balanced crystalloid at 500–1,000 mL/hr for 2–4 hours in adults without cardiac/renal compromise, reassessing perfusion. Older adults and patients with heart failure or dialysis dependence need smaller boluses (e.g., 250 mL) and frequent reassessment.
- Corrected Sodium Calculation: (Add 1.6 mEq/L for every 100 mg/dL glucose elevation above 100 mg/dL).
- Subsequent Infusion: Adjust rate and composition to hydration, blood pressure, fluid balance, sodium and osmolality. In HHS, sodium commonly rises as glucose falls; this alone does not require hypotonic fluid. Use 0.45% saline only if osmolality is not declining despite adequate positive fluid balance and appropriate insulin. Aim for an osmolality decline of 3–8 mOsm/kg/hr and sodium decline no greater than 10 mEq/L/24 h.
- Resuscitation Targets: Urine output mL/kg/hr, normalized heart rate, and stable blood pressure.
Potassium Replenishment Protocol
Total body potassium is depleted (3–5 mEq/kg deficit) from osmotic kaliuresis, yet baseline serum levels may be normal or high due to insulinopenia and acidemia. Insulin drives potassium into myocytes via -ATPase activation, causing precipitous serum drops:
- Potassium <3.5 mEq/L: HOLD INSULIN. Begin IV potassium replacement, typically 10 mEq/hr, and delay insulin until potassium is >3.5 mEq/L. More intensive replacement requires an appropriate monitored protocol and vascular access.
- Potassium 3.5–5.0 mEq/L: Usually add 20–30 mEq potassium per liter to maintain 4–5 mEq/L, accounting for renal function and urine output.
- Potassium >5.0 mEq/L: Initially withhold potassium; replace once it falls below 5.0. Check potassium 2 hours after insulin starts and every 4 hours thereafter, more often when clinically indicated.
- Phosphate: Do not replace routinely. Consider replacement for muscle weakness with respiratory/cardiac compromise and phosphate <1.0 mmol/L; avoid rapid replacement and monitor calcium.
Regular Insulin Infusion & Dextrose Transition
Insulin therapy must never precede crystalloid resuscitation and potassium verification:
- Infusion Regimen: Start IV regular insulin 0.1 units/kg/hr for DKA or mixed DKA/HHS after initial fluid and potassium assessment. For HHS with beta-hydroxybutyrate <3.0 mmol/L, pH ≥7.30 and bicarbonate ≥18 mEq/L, use 0.05 units/kg/hr. A routine bolus is unnecessary when prompt infusion is available.
- Monitor the Response: Check glucose every 1–2 hours and electrolytes, venous pH and beta-hydroxybutyrate every 4 hours; also follow osmolality in HHS. Adjust insulin to the monitored response. In HHS, avoid glucose declines exceeding 90–120 mg/dL/hr; target an osmolality decline of 3–8 mOsm/kg/hr.
- The Dextrose Bridge: When glucose falls below 250 mg/dL, add 5–10% dextrose to replacement fluid. Reduce the DKA infusion to 0.05 units/kg/hr, adjusting it and dextrose to keep glucose around 200 mg/dL while clearing ketones. Continue HHS treatment until hyperosmolality and clinical abnormalities resolve.
Warning
The Premature Insulin Cessation Trap: A dangerous pitfall is stopping insulin when glucose hits 200 mg/dL. In DKA, insulin is required to suppress lipolysis and clear ketonemia. Halting insulin prematurely triggers recurrent ketoacidosis. Adding dextrose prevents hypoglycemia and rapid osmolality drops that cause cerebral edema, allowing uninterrupted insulin delivery until acidosis clears.
Resolution Criteria & Subcutaneous Transition
- DKA Resolution Criteria: Plasma beta-hydroxybutyrate <0.6 mmol/L plus venous pH ≥7.30 or bicarbonate ≥18 mEq/L; ideally glucose is <200 mg/dL. Anion gap can be misleading during recovery because saline-related hyperchloremic acidosis may persist after ketones clear.
- HHS Resolution Criteria: Serum osmolality <300 mOsm/kg, glucose <250 mg/dL, urine output >0.5 mL/kg/hr, and improved cognition.
- Subcutaneous Transition Protocol:
- Transition when alert, stable, and tolerating oral intake.
- Basal Insulin Depot: Administer subcutaneous basal insulin (glargine or degludec at 0.2–0.3 units/kg, or home baseline) 2 to 4 hours PRIOR to stopping IV insulin.
- Pharmacokinetic Rationale: IV regular insulin has a half-life of 5–9 minutes. Stopping the drip without a subQ depot leaves an immediate insulin void, triggering rapid rebound ketoacidosis.
A 28-year-old male with type 1 diabetes presents to the emergency department with severe diabetic ketoacidosis. Initial point-of-care capillary blood glucose is 480 mg/dL, arterial blood gas demonstrates pH 7.12, serum bicarbonate is 9 mEq/L, and serum beta-hydroxybutyrate is 5.4 mmol/L. Initial serum chemistry reveals sodium 134 mEq/L and potassium 2.9 mEq/L. Intravenous access is established, and isotonic fluid resuscitation is initiated. What is the mandatory next step in the pharmacologic management protocol before insulin infusion can be started?
Administer an intravenous regular insulin bolus of 0.1 units/kg followed immediately by a continuous infusion at 0.1 units/kg/hr
Withhold insulin, begin monitored intravenous potassium replacement (typically 10 mEq/hr), and delay insulin until serum potassium is >3.5 mEq/L
Administer 100 mEq of intravenous sodium bicarbonate with 20 mEq potassium chloride over 30 minutes
Initiate a low-dose regular insulin infusion at 0.05 units/kg/hr without a bolus while simultaneously infusing 5% dextrose
A 32-year-old female with DKA has received 4 hours of intravenous regular insulin at 0.1 units/kg/hr and 3 liters of isotonic crystalloid. Repeat laboratory testing demonstrates: plasma glucose 194 mg/dL, arterial pH 7.24, serum bicarbonate 13 mEq/L, serum potassium 4.4 mEq/L, and anion gap 17 mEq/L. The patient remains alert but reports mild nausea. What is the most appropriate next step in intravenous fluid and insulin titration?
Discontinue the intravenous insulin infusion immediately and transition the patient to subcutaneous rapid-acting insulin lispro
Increase the intravenous regular insulin infusion rate to 0.2 units/kg/hr to accelerate closure of the metabolic anion gap
Add 5–10% dextrose to the intravenous fluids, reduce insulin to 0.05 units/kg/hr with monitored adjustment, and continue until ketoacidosis resolves
Administer an intravenous bolus of 50 mEq sodium bicarbonate and discontinue intravenous fluids
A 21-year-old male with DKA has achieved clinical and biochemical resolution with a blood glucose of 162 mg/dL, venous pH 7.36, serum bicarbonate 20 mEq/L, beta-hydroxybutyrate 0.4 mmol/L, and anion gap 9 mEq/L. He is hungry and tolerating clear liquids. The acute care nurse practitioner is preparing to transition the patient from intravenous regular insulin to a subcutaneous basal-bolus regimen. How should the transition be executed to prevent recurrent ketoacidosis?
Administer subcutaneous basal insulin 2 to 4 hours prior to discontinuing the intravenous regular insulin infusion
Discontinue the intravenous insulin infusion immediately and administer subcutaneous basal insulin 2 hours after the next meal
Stop the intravenous insulin infusion and initiate an oral sulfonylurea and metformin regimen
Wean the intravenous regular insulin infusion by 50% every 2 hours until the drip rate reaches zero, without administering subcutaneous basal insulin
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