A 28-year-old man with type 1 diabetes mellitus presents to the emergency department with Kussmaul respirations, fruity-smelling breath, and altered mental status. Blood glucose is 450 mg/dL, arterial pH 7.18, HCO₃⁻ 12 mEq/L, and serum ketones are strongly positive. What is the most common precipitating cause of diabetic ketoacidosis in this patient?

Explanation

## Most Common Precipitant of DKA **Key Point:** Infection is the most common precipitating cause of DKA in type 1 diabetes, accounting for approximately 30–50% of cases. Urinary tract infections and pneumonia are the most frequent infectious triggers. ### Why Infection Dominates Infections trigger DKA through multiple mechanisms: 1. **Increased counter-regulatory hormones** — stress response elevates glucagon, catecholamines, and cortisol 2. **Increased lipolysis** — leads to free fatty acid mobilization and ketone body production 3. **Decreased insulin efficacy** — inflammatory cytokines impair insulin signalling 4. **Hyperglycemia worsening** — infection causes glucose intolerance ### Other Important Precipitants (in order of frequency) | Precipitant | Frequency | Notes | | --- | --- | --- | | **Infection** | 30–50% | UTI, pneumonia, skin/soft tissue | | **Omission/inadequate insulin** | 20–30% | Often in young patients with poor adherence | | **Acute illness** (MI, stroke, pancreatitis) | 10–20% | Stress response triggers ketogenesis | | **Medications** (steroids, SGLT2 inhibitors) | 5–10% | SGLT2i-associated euglycemic DKA | | **Alcohol abuse** | 5% | Impairs gluconeogenesis and metabolism | | **Pregnancy** | Rare | Increased insulin requirements | **High-Yield:** In clinical practice, always screen for infection (urinalysis, blood cultures, chest X-ray, lactate) in every DKA patient before attributing it to non-compliance. **Clinical Pearl:** Infection may be clinically silent in DKA — fever and leukocytosis can be absent or blunted. A high index of suspicion is essential. ### Why Other Options Are Wrong **Myocardial infarction** — While MI can precipitate DKA through acute stress and catecholamine surge, it accounts for <10% of cases and is far less common than infection. **Stroke** — Similarly, stroke is a rare precipitant (<5%) and does not account for the majority of DKA presentations. **Hyperthyroidism** — Thyroid disease is an uncommon trigger for DKA and is not a standard precipitant in most reviews.