The mannose phosphate isomerase-congenital disorder of glycosylation (MPI-CDG) is caused by phosphomannose
isomerase deficiency. Clinical features include hyperinsulinaemic hypoglycaemia, protein losing enteropathy,
hepatomegaly and hepatic fibrosis, digestive symptoms and coagulation abnormalities. The condition
is treated with mannose supplementation. Long-term outcomes in adults are not well described. We present a
case of an adult female patient who discontinued mannose therapy in her adolescence. In adulthood she developed
gastrointestinal problems, chronic anaemia and osteophytes in her knees.