Protein-sensitive hypoglycemia without leucine sensitivity in hyperinsulinism caused by K(ATP) channel mutations

OBJECTIVE

Because children with congenital hyperinsulinism (HI) caused by recessive loss of function mutations in the adenosine triphosphate (ATP)-dependent potassium channel (K(ATP)-HI) are not leucine sensitive, we evaluated for protein-induced hypoglycemia with oral protein tolerance tests.

STUDY DESIGN

Blood glucose and insulin concentrations were measured every 15 minutes for 3 hours after an oral protein load in children with K(ATP)-HI (n = 11) and compared with those of children with glutamate dehydrogenase HI (n = 12) and control subjects (n = 12).

RESULTS

Similar to children with glutamate dehydrogenase HI, patients with K(ATP)-HI displayed protein-induced hypoglycemia (10/11) with blood glucose concentrations declining by 17 to 69 mg/dL. In contrast, oral protein had little effect on blood glucose concentrations in control subjects.

CONCLUSIONS

Protein-induced hypoglycemia is a feature of K(ATP)-HI, despite the absence of leucine sensitivity. The results indicate that amino acids can stimulate insulin secretion via a glutamate dehydrogenase- and K(ATP) channel-independent pathway.

Hyperglycemic hyperosmolar non-ketotic syndrome in children with type 2 diabetes*

OBJECTIVE

Hyperglycemic hyperosmolar non-ketotic (HHNK) syndrome is thought to be a rare entity in the pediatric population, associated with significant mortality based on case reports in the literature. As obesity and type 2 diabetes in childhood grow in prevalence, such related complications may also increase. This study will serve to provide updated information regarding typical clinical course and sequelae of HHNK syndrome in childhood.

METHODS

Patients diagnosed with type 2 diabetes at Children's Hospital of Philadelphia (CHOP) over a period of 5 yr were screened retrospectively for any laboratory evidence of previous episodes of HHNK syndrome. The standard diagnostic criteria of blood glucose >600 mg/dL and serum osmolality >330 mOsm/L with only mild acidosis (serum bicarbonate >15 mmol/L and small ketonuria 15 mg/dL or less) were utilized.

RESULTS

The records of all patients with type 2 diabetes mellitus (DM) diagnosed over a 5-yr period were reviewed (n=190). Seven patients were found to have one episode of HHNK syndrome by diagnostic criteria (five males, mean age at presentation 13.3 yr, age range 10.1--16.9 yr), yielding a frequency of 3.7%. All were African-American. HHNK syndrome was the clinical presentation at diagnosis of new onset diabetes for all seven children. Three of seven children had a previously diagnosed developmental delay. The average Glasgow Coma Scale (GCS) score at presentation was 13 (range 9--15). Mean body mass index (BMI) at presentation was 32.7 kg/m(2) (n=6). Mean serum osmolality was 393 mOsm/L (n=7), and mean blood glucose was 1604 mg/dL (n = 7). The average time until mental status returned to baseline among survivors was 3 d (range 1--7 d). The average number of hospital days for survivors was 10 (range 5--24 d). Four of seven patients had an uncomplicated course. One patient developed multisystem organ failure and died on hospital day 4. The case fatality rate was 14.3% (one of seven). Survivors had no appreciable neurodevelopmental sequelae.

CONCLUSIONS

This retrospective chart review provides updated information regarding the entity of HHNK syndrome in children. This study supports the need for increased awareness of type 2 diabetes in children so that morbidity and mortality related to HHNK syndrome can be prevented.