Figure 6. HI Diagnostic and Treatment Algorithm. Once HI is diagnosed, effectiveness of diazoxide treatment needs to be assessed. Responsiveness to diazoxide is shown by demonstrating the ability to fast an age-appropriate interval (minimum 9 hours for neonate) with plasma glucose >70 mg/dL and/or generate beta-hydroxybutyrate >2 mmol/L prior to plasma glucose <50 mg/dL. For patients unresponsive to diazoxide, expedited genetic testing is obtained to differentiate diffuse and focal forms of HI. 18F-DOPA PET/CT is performed when genetic testing is suggestive of possible focal disease. For patients with diffuse, diazoxide-unresponsive disease, intensive medical therapy is initiated, with near-total pancreatectomy reserved for medically unresponsive cases. 18F-DOPA PET/CT 18-fluoro-L-3,4-dihydroxyphenylalanine positron emission tomography.