Presentation
A 54-year-old man with no prior medical care presents with 6 weeks of increased thirst, frequent urination, and mild fatigue. He denies chest pain, headache, dyspnea, visual changes, or focal weakness. A screening blood pressure is markedly elevated and a point-of-care random glucose is 268 mg/dL.
Initial observations
- BP 192/110 mmHg
- HR 84
- RR 16
- Temp 98.4°F (36.9°C)
- SpO2 98% on room air
- BMI 33
Which single test best establishes the diagnosis and guides initial therapy?