Permanent neonatal diabetes mellitus (PNDM) is a type of diabetes that first appears within the first six months of life. This form of diabetes is associated with partial or complete insulin deficiency. This type of neonatal diabetes is caused by activating mutations of the KCNJ11 gene.
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Symptoms of Permanent Neonatal Diabetes Mellitus
- Individuals with permanent neonatal diabetes mellitus experience slow growth before birth (intrauterine growth retardation).
- Affected infants have hyperglycemia and an excessive loss of fluids (dehydration)
- Affected infants are unable to gain weight and grow at the expected rate (failure to thrive).
- In some cases, people with permanent neonatal diabetes mellitus also have certain neurological problems, including developmental delay and recurrent seizures (epilepsy).
Causes of Symptoms of Permanent Neonatal Diabetes Mellitus
Permanent neonatal diabetes mellitus may be caused by mutations in several genes.
- Mutations in the KCNJ11 gene
- Mutations in the ABCC8 gene
- Mutations in the INS gene
Permanent neonatal diabetes mellitus can also be caused by mutations in other genes, some of which have not been identified.
Diagnosis of Permanent Neonatal Diabetes Mellitus
Permanent neonatal diabetes mellitus should be suspected in individuals with the following laboratory and radiographic features:
- Persistent hyperglycemia (plasma glucose concentration >150-200 mg/dL) in infants younger than age six months
- Features typical of diabetes mellitus (e.g., glucosuria, ketonuria, hyperketonemia)
- Low or undetectable plasma insulin and C-peptide relative to the hyperglycemia
- Low fecal elastase and high stool fat in infants with pancreatic aplasia or hypoplasia
Note: Measurement of hemoglobin A1c is not suitable for diagnosing diabetes mellitus in infants younger than age six months because of the higher proportion of fetal hemoglobin compared to hemoglobin A.
- Pancreatic hypoplasia identified on ultrasound, CT, or MRI examination
Note: Visualization of the pancreas in neonates may be difficult; biochemical evidence of pancreatic insufficiency (e.g., low fecal elastase, high stool fat) may help with the diagnosis in these infants.