A 28-year-old man with type 1 diabetes mellitus presents to the emergency department with severe metabolic acidosis, Kussmaul respirations, and altered mental status. Blood glucose is 450 mg/dL, arterial pH 7.15, and serum bicarbonate 8 mEq/L. What is the most common precipitating cause of diabetic ketoacidosis in this patient?

Explanation

## Most Common Precipitating Causes of DKA **Key Point:** Infection is the single most common precipitating factor in DKA, accounting for approximately 30–50% of cases in most series. ### Frequency Distribution of DKA Precipitants | Precipitant | Frequency (%) | Common Examples | |---|---|---| | **Infection** | 30–50 | UTI, pneumonia, sepsis, meningitis | | Insulin omission/non-compliance | 20–30 | Missed doses, pump failure | | New-onset diabetes | 10–15 | First presentation of T1DM | | Cardiovascular events | 5–10 | MI, stroke, arrhythmia | | Medications | 2–5 | Corticosteroids, SGLT2 inhibitors | | Trauma/surgery | 2–5 | Post-operative state | | Other endocrine | <2 | Hyperthyroidism, pheochromocytoma | **High-Yield:** In clinical practice, always screen for infection (CBC, urinalysis, blood culture, CXR) in every DKA patient, even if the patient denies symptoms. Infection may be subtle or absent in diabetic patients due to impaired immune response. **Clinical Pearl:** UTIs and pneumonia are the most frequently identified infections in DKA; however, any infection can precipitate the condition. Sepsis itself can cause metabolic acidosis, compounding the picture. **Mnemonic — DKA Precipitants (SICK):** - **S** — Sepsis/Infection - **I** — Insulin omission/non-compliance - **C** — Cardiovascular events (MI, stroke) - **K** — Ketoacidosis (new-onset diabetes) ### Why Infection is the Leading Cause 1. Infection triggers release of counter-regulatory hormones (cortisol, catecholamines, glucagon). 2. These hormones increase lipolysis and free fatty acid mobilization. 3. Increased FFA flux to the liver drives ketone body production. 4. Simultaneously, infection impairs insulin secretion and increases insulin resistance. 5. The combination of increased ketogenesis and decreased glucose utilization precipitates DKA. **Warning:** Do not assume DKA is due to insulin omission without excluding infection first. A patient may have omitted insulin *because* they were ill with an infection. [cite:Harrison 21e Ch 396]