Pregnancies complicated by GDM are associated with a higher frequency of adverse maternal and fetal outcomes. The outcomes seem to be unaffected by treatment modality. However, because of the potential risk of hypoglycaemia in some neonates, tolbutamide treatment cannot be recommended in pregnancy.

Christesen HBT, Feilberg-Jørgensen N, Brock Jacobsen B. Pancreatic beta-cell stimulation tests in transient and persistent congenital hyperinsulinism. Acta Paediatr 2001; 90: 1116-1120 In congenital hyperinsulinism (HI), the in vivo pancreatic b-cell function is poorly described. Among 14 neonates with severe hyperinsulinaemic hypoglycaemia, 2 patients had very prolonged or persistent hypoglycaemia and mutation in the sulphonylurea receptor SUR1 gene. Patient 1 had transient HI and was treated medically for 3.5 mo before clinical remission was seen. He had initially very high basal and stimulated C-peptide and insulin levels, followed by a state of normal preprandial values, but blunted b-cell glucose sensitivity, before complete b-cell normalization occurred. A single, paternal SUR1 mutation, G1382S, was found suggesting focal type HI. Patient 2 had persistent HI and underwent 3 pancreas resections up to the age of 2 y, 7 mo, followed by a state of mild diabetes. On biopsy, diffuse-type b-cell hypertrophy was seen. The b-cell response to glucose and glucagon stimulation was blunted before, as well as after, pancreas resections. Compound heterozygosity for the SUR1 mutations 3992-3c to g and N188S was found.Conclusion: Transient, possibly focal, HI with paternal SUR1 mutation was associated with a gradual, but complete normalization of the in vivo b-cell function; in the diffuse type HI, a blunted b-cell response to glucose and glucagon stimulation persisted. In vivo b-cell stimulation tests may contribute to the characterization of the HI subtypes.