Hypersulinemic hypoglycemia as a presenting sign in phosphomannose isomerase deficiency: A new manifestation of carbohydrate-deficient glycoprotein syndrome treatable with mannose

We report the case of a patient with carbohydrate-deficient glycoprotein sy ndrome type Ib who developed normally until 3 months of age, when she was r eferred to the hospital for evaluation of hypoglycemia that was found to be related to hyperinsulinism. She also had vomiting episodes, hepatomegaly, and intractable diarrhea, which evoked the diagnosis of carbohydrate-defici ent glycoprotein syndrome. Oral mannose treatment at a dose of 0.17 g/kg bo dy weight 6 times/d was followed by a clinical improvement and normalizatio n of blood glucose, aminotransferases, and coagulation factor levels. Hyper insulinemic hypoglycemia should be considered as a leading sign of carbohyd rate-deficient glycoprotein syndrome type Ib, especially when it is associa ted with enteropathy and abnormal liver tests.