A 52-year-old woman with Type 2 diabetes on metformin presents with fatigue and mild ketonemia (0.8 mmol/L). Which finding best distinguishes euglycemic diabetic ketoacidosis (euDKA) from classical DKA in this patient?

Explanation

## Euglycemic DKA vs Classical DKA ### Definition and Pathophysiology **Key Point:** Euglycemic DKA is a rare but life-threatening variant of DKA where metabolic acidosis and significant ketonemia occur WITH serum glucose <250 mg/dL (often 100–200 mg/dL), creating a diagnostic trap. ### Comparison Table | Feature | Classical DKA | Euglycemic DKA | | --- | --- | --- | | **Serum Glucose** | >250 mg/dL (hyperglycemic) | <250 mg/dL (euglycemic/mildly elevated) | | **Arterial pH** | <7.30 (severe acidosis) | <7.30 (severe acidosis) | | **Anion Gap** | >12 (high) | >12 (high) | | **Serum Ketones** | Markedly elevated | Markedly elevated | | **Diagnostic Clue** | Obvious (hyperglycemia + ketosis) | **MISSED** (glucose not elevated) | | **Associated Triggers** | Type 1 DM, infection, MI | SGLT2i use, Type 2 DM, fasting | | **Mortality Risk** | High if untreated | **VERY HIGH** (delayed diagnosis) | ### Pathophysiology of EuDKA **High-Yield:** Euglycemic DKA typically occurs in patients on SGLT2 inhibitors (empagliflozin, dapagliflozin) or during prolonged fasting in Type 2 diabetes. The mechanism: 1. **SGLT2 inhibitors** → increased urinary glucose excretion → mild glycosuria-induced osmotic diuresis → relative euglycemia 2. **Paradoxical ketogenesis** → lipolysis continues unchecked despite low glucose 3. **Insulin levels** → may be present (Type 2 DM context) but insufficient to suppress ketogenesis 4. **Result** → severe metabolic acidosis + ketonemia WITHOUT the warning sign of hyperglycemia ### Why This is a Diagnostic Trap **Warning:** Clinicians may miss euDKA because: - Blood glucose is NOT elevated (patient/provider may assume "no DKA") - Symptoms (fatigue, dyspnea, nausea) are nonspecific - Arterial blood gas and anion gap are the key diagnostic clues - Delay in diagnosis → worse outcomes **Clinical Pearl:** Always check **arterial pH and anion gap** in any diabetic patient with ketonemia, regardless of glucose level. Euglycemic DKA is increasingly recognized with SGLT2i use. ### Mnemonic **SGLT2-euDKA**: **S**GLT2i → **G**lucose euglycemic → **L**ipolysis unchecked → **T**wo problems (acidosis + ketones, no hyperglycemia) → **2** = Type 2 DM context. [cite:Harrison 21e Ch 396; Endocrinology 2021 Guidelines on SGLT2i]