Congenital hyperinsulinism can be divided into diffuse or focal form. The treatment and outcome depend on distinguishing between the 2 forms. Pancreatic venous sampling was the only method available to localize the insulin secretion. [F]Fluoro-levodopa, 3,4-dihydroxy-L-phenylalanine positron emission tomography/computed tomography is a noninvasive imaging investigation and increasingly used to determine the type of hyperinsulinism preoperatively. We present a case of diffuse form of congenital hyperinsulinism demonstrated by the [F]levodopa, 3,4-dihydroxy-L-phenylalanine positron emission tomography/computed tomography preoperatively and review the literature.