Neonatal Diabetes Mellitus
Neonatal diabetes mellitus presents as hyperglycemia, failure to thrive and, in some cases, dehydration and ketoacidosis which may be severe with coma, in a child within the first months of life.
Transient (TNDM) and Permanent (PNDM) neonatal diabetes are rare conditions occurring in 1:300,000-400,000 live births.
TNDM infants develop diabetes in the first few weeks of life but go into remission in a few months, with possible relapse to a permanent diabetes state usually around adolescence or as adults. The pancreatic dysfunction may be maintained throughout life, with relapse initiated at times of metabolic stress such as puberty or pregnancy. Patients with TNDM are more likely to have intrauterine growth retardation and less likely to develop ketoacidosis than patients with PNDM. In TNDM, patients are younger at the diagnosis of diabetes and have lower initial insulin requirements. In PNDM, insulin secretory failure occurs in the late fetal or early post-natal period and does not go into remission. Considerable overlap occurs between the two groups, so that TNDM cannot be distinguished from PNDM based on clinical features. Very early onset diabetes mellitus seems to be unrelated to autoimmunity in most instances.
A number of conditions are associated with PNDM, some of which have been elucidated at the molecular level. Among these, the very recently elucidated mutations in the KCNJ11 and ABCC8 genes, encoding the Kir6.2 and SUR1 subunit of the pancreatic KATP channel involved in regulation of insulin secretion, account for one third to half of the PNDM cases.
Molecular analysis of chromosome 6 anomalies, and the KCNJ11 and ABCC8 genes encoding Kir6.2 and SUR1, provides a tool to identify TNDM from PNDM in the neonatal period. This analysis also has potentially important therapeutic consequences leading to transfer some patients, those with mutations in KCNJ11 and ABCC8 genes, from insulin therapy to sulfonylureas.
Management and treatment
Recurrent diabetes is common in patients with 'transient'' neonatal diabetes mellitus and, consequently, prolonged follow-up is imperative. Insulin pump may offer an interesting therapeutic tool in this age group in experienced hands.