Diabetic keto acidosis
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"diabetic ketoacidosis"[MeSH Terms] AND management
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Diabetic Ketoacidosis (DKA)
Definition
DKA is defined by three core biochemical abnormalities (the "DKA triad"):
- Hyperglycemia (blood glucose >250 mg/dL, though it can vary widely)
- Ketonemia/ketonuria (urine ketones ≥2+ or serum ketones ≥3.0 mmol/L)
- Acidosis (arterial or venous pH <7.3, serum bicarbonate <18 mmol/L)
Severity is classified as mild (pH 7.25-7.3), moderate (pH 7.0-7.25), or severe (pH <7.0).
Pathophysiology
The core problem is absolute or relative insulin deficiency combined with excess counter-regulatory hormones (glucagon, cortisol, catecholamines, growth hormone).
Three major consequences:
-
Hyperglycemia - Insulin deficiency impairs peripheral glucose uptake; glucagon drives hepatic gluconeogenesis and glycogenolysis. When glucose exceeds the renal threshold, osmotic diuresis begins, causing massive losses of water, sodium, potassium, magnesium, calcium, and phosphorus.
-
Ketogenesis - Insulin deficiency activates hormone-sensitive lipase in adipose tissue, flooding the circulation with free fatty acids (FFAs). The liver partially oxidizes these long-chain FFAs into ketone bodies: beta-hydroxybutyrate (beta-OHB), acetoacetate, and acetone. Beta-OHB predominates (up to 75-80%) but is NOT detected by standard nitroprusside-based urine dipstick tests.
-
Metabolic acidosis - Ketone accumulation overwhelms the body's buffering capacity. Bicarbonate is consumed, producing a wide anion gap metabolic acidosis. Kussmaul breathing (deep, rapid respirations) represents the respiratory compensation attempt to blow off CO2.
The resulting dehydration causes hemoconcentration, which worsens hyperglycemia and hyperosmolality - a vicious cycle.
Precipitating Causes
| Common | Other |
|---|---|
| Infection (most common) | Acute coronary syndrome |
| Missed/inadequate insulin | Stroke, PE, pancreatitis |
| New-onset T1DM | Cushing syndrome, thyrotoxicosis |
| Unknown | SGLT-2 inhibitors (euglycemic DKA) |
| Cocaine, corticosteroids, antipsychotics (clozapine, olanzapine) |
Note on SGLT-2 inhibitors: These can trigger DKA at normal or near-normal glucose levels (euglycemic DKA) - a diagnostic pitfall.
Clinical Features
Symptoms (hours to days of progression):
- Polyuria, polydipsia, polyphagia
- Nausea, vomiting, anorexia
- Generalized weakness, fatigue
- Diffuse abdominal pain (can mimic acute abdomen - due to ileus/gastroparesis)
- Fruity/acetone breath
Signs:
- Dehydration: dry mucous membranes, reduced skin turgor, sunken eyes
- Tachycardia, hypotension (orthostatic or frank)
- Kussmaul breathing (deep, rapid, labored)
- Altered mental status - ranges from lethargy to frank coma (severity correlates with hyperosmolality)
- Hypothermia (despite infection as precipitant, fever is often absent due to peripheral vasodilation)
Diagnosis - Laboratory Findings
| Test | Finding |
|---|---|
| Blood glucose | Typically 250-600 mg/dL (can be higher or even near-normal with SGLT-2i) |
| Serum ketones | Elevated; beta-OHB preferred over nitroprusside |
| Arterial/venous pH | <7.3 |
| Serum HCO3 | <18 mmol/L |
| Anion gap | Elevated (>12 mEq/L) |
| Serum potassium | Normal or HIGH initially (despite total-body deficit due to acidosis shift) |
| Serum sodium | Often low (pseudohyponatremia from osmotic dilution) |
| BUN/Creatinine | Elevated (prerenal AKI) |
| WBC | Elevated (even without infection - ketosis itself causes leukocytosis) |
| Serum amylase | May be elevated - often non-pancreatic origin; use lipase for pancreatitis |
| Hemoglobin/Hematocrit | Elevated (hemoconcentration) |
Key diagnostic pitfall: The nitroprusside urine/serum ketone test reacts with acetoacetate but NOT with beta-hydroxybutyrate (the predominant ketone in DKA). This can underestimate severity. Always check serum beta-OHB directly when available. Conversely, after insulin therapy begins, the test may appear falsely elevated for hours as acetone clears slowly.
Corrected sodium: Add 1.6-2.4 mEq/L to measured sodium for every 100 mg/dL glucose above 100 mg/dL.
Management
1. Fluid Resuscitation (Most Important First Step)
- Adults: 1-2 L of isotonic normal saline (0.9% NaCl) over 1-3 hours initially, then 0.45% NaCl at 250-500 mL/hr
- Children: 20 mL/kg NS over first hour
- Switch to D5W/0.45% NS when glucose falls to ≤250-300 mg/dL (to prevent hypoglycemia while continuing insulin)
- Total deficits are 3-5 liters in adults, up to 70-90 mL/kg
Recent evidence (2024): A systematic review and meta-analysis (PMID 38925619) found that balanced electrolyte solutions (e.g., lactated Ringer's, Plasmalyte) achieve faster DKA resolution than 0.9% saline, and reduce the risk of hyperchloremic metabolic acidosis that can mask resolution.
2. Potassium Replacement (Critical Before Insulin)
| Serum K+ | Action |
|---|---|
| <3.3 mEq/L | Hold insulin, replace K+ to ≥3.3 mEq/L first (IV 20-40 mEq/hr) |
| 3.3-5.5 mEq/L | Give K+ 20-40 mEq per liter of IV fluid, start insulin |
| >5.5 mEq/L | No K+ supplement yet; reassess after insulin starts |
Rationale: Insulin drives K+ intracellularly. Starting insulin with K+ <3.3 mEq/L risks fatal cardiac arrhythmias.
3. Insulin
- Standard: Regular insulin IV infusion at 0.1 units/kg/hour (no IV bolus recommended)
- Target: Glucose decrease of 50-75 mg/dL per hour
- Do NOT stop insulin until acidosis resolves (pH >7.3, HCO3 >18, anion gap closed) - not just until glucose normalizes
- Add dextrose (D5W) to IV fluids once glucose ≤250-300 mg/dL so insulin can continue clearing ketones
- Subcutaneous insulin is safe and effective in mild DKA (well-hydrated patients with mild acidemia)
Recent evidence (2026): A meta-analysis of RCTs (PMID 41208563) found early subcutaneous basal insulin combined with IV insulin infusion reduces rebound hyperglycemia and DKA recurrence during transition off IV insulin.
Recent evidence (2024): Subcutaneous vs. continuous IV insulin meta-analysis (PMID 39090718) confirmed subcutaneous protocols are non-inferior in selected mild-moderate DKA patients.
4. Bicarbonate
- Generally NOT recommended unless pH <6.9 (severe acidosis with hemodynamic instability)
- Risks of bicarbonate: paradoxical CSF acidosis, hypokalemia, delayed ketone clearance, cerebral edema (especially in children)
5. Phosphate
- Routine replacement is not indicated (no strong evidence of benefit)
- Replace with potassium phosphate only if serum phosphate <1.0 mg/dL (very severe hypophosphatemia)
6. Magnesium
- Replace if hypomagnesemia is documented (1-2 g MgSO4 IV)
7. Identify and Treat the Precipitant
- Blood cultures, urine culture, CXR
- ECG (to rule out ACS as trigger and to monitor K+ effects)
- Treat underlying infection with antibiotics
Monitoring
Meticulous flow sheets should track every 1-2 hours:
- Vital signs, urine output
- Blood glucose (hourly initially)
- Serum electrolytes (K+, Na+, Cl-, HCO3-)
- Blood gas (pH)
- Anion gap
- Amount of insulin given
Resolution criteria (all three must be met):
- Blood glucose <200 mg/dL
- Serum HCO3 ≥15 mEq/L
- Venous pH >7.3
- Anion gap ≤12
Complications of DKA and its Treatment
| Complication | Notes |
|---|---|
| Cerebral edema | Most feared, especially in children (incidence ~1%); avoid rapid fluid shifts and excessive free water; presents with headache, mental status change during treatment |
| Hypokalemia | Most dangerous in-treatment complication; from insulin + fluid resuscitation |
| Hypoglycemia | From inadequate dextrose once glucose falls |
| Aspiration pneumonia | Gastroparesis + altered consciousness; consider NGT |
| Thrombosis | Hypercoagulable state; DVT/PE risk |
| ARDS | Rare, related to aggressive crystalloid use and inflammatory state |
| Hyperchloremic acidosis | From excessive NS; can obscure true resolution |
DKA vs. HHS (Hyperosmolar Hyperglycemic State)
| Feature | DKA | HHS |
|---|---|---|
| Typical patient | Type 1 DM, younger | Type 2 DM, elderly |
| Glucose | 250-600 mg/dL | >600 mg/dL (often >1000) |
| Ketones | Marked | Minimal/absent |
| pH | <7.3 | Usually >7.3 |
| Bicarbonate | <18 mEq/L | >18 mEq/L |
| Osmolality | Mildly elevated | Markedly elevated (>320 mOsm/kg) |
| Neurologic signs | Variable | Prominent (correlates with osmolality) |
| Mortality | <10% (with treatment) | Higher (~5-20%) |
Some patients present with a mixed picture, particularly those with T2DM and depressed insulin secretion.
Special Situations
- Pregnancy: DKA can occur at lower glucose thresholds due to physiologic respiratory alkalosis. Aggressive management required due to fetal risk; fetal monitoring essential.
- Children: Greater risk of cerebral edema. Fluid rates should be conservative. Avoid bicarbonate.
- SGLT-2 inhibitor-related DKA: Euglycemic DKA - do not be falsely reassured by near-normal glucose. Ketone levels are the key diagnostic finding.
Sources:
- Goldman-Cecil Medicine (International Edition), Chapter 210
- Rosen's Emergency Medicine: Concepts and Clinical Practice, Chapter 115
- Recent meta-analyses: PMID 38925619 (balanced fluids vs. NS), PMID 39090718 (SC vs. IV insulin), PMID 41208563 (early basal SC insulin)
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