Exceptional diazoxide sensitivity in hyperinsulinaemic hypoglycaemia due to a novel HNF4A mutation

Summary Diazoxide is the first-line treatment for patients with hyperinsulinaemic hypoglycaemia (HH). Approximately 50% of patients with HH are diazoxide resistant. However, marked diazoxide sensitivity resulting in severe hyperglycaemia is extremely uncommon and not reported previously in the context of HH due to HNF4A mutation. We report a novel observation of exceptional diazoxide sensitivity in a patient with HH due to HNF4A mutation. A female infant presented with severe persistent neonatal hypoglycaemia and was diagnosed with HH. Standard doses of diazoxide (5 mg/kg/day) resulted in marked hyperglycaemia (maximum blood glucose 21.6 mmol/L) necessitating discontinuation of diazoxide. Lower dose of diazoxide (1.5 mg/kg/day) successfully controlled HH in the proband, which was subsequently confirmed to be due to a novel HNF4A mutation. At 3 years of age, the patient maintains age appropriate fasting tolerance on low dose diazoxide (1.8 mg/kg/day) and has normal development. Diagnosis in proband’s mother and maternal aunt, both of whom carried HNF4A mutation and had been diagnosed with presumed type 1 and type 2 diabetes mellitus, respectively, was revised to maturity-onset diabetes of young (MODY). Proband’s 5-year-old maternal cousin, also carrier of HNF4A mutation, had transient neonatal hypoglycaemia. To conclude, patients with HH due to HNF4A mutation may require lower diazoxide than other group of patients with HH. Educating the families about the risk of marked hyperglycaemia with diazoxide is essential. The clinical phenotype of HNF4A mutation can be extremely variable. Learning points: Awareness of risk of severe hyperglycaemia with diazoxide is important and patients/families should be accordingly educated. Some patients with HH due to HNF4A mutations may require lower than standard doses of diazoxide. The clinical phenotype of HNF4A mutation can be extremely variable.

Study of the hyperglycemic condition in diseases of liver in non-obese clinical patients

Hyperglycemia is best documented by Whipple´s triad: symptoms compatible with hypoglycemia, low blood glucose concentration and alleviation of symptoms after the glucose concentration is raised. In experimental studies in healthy adults, fifteen out of the 19 patients who developed hypoglycaemia on the fasts during MT were re-tested 3 to 4 months after cessation of therapy. Fasting tolerance had improved in all of them. It had become normal in 10 out of 15 patients (67%). In 5 patients, blood glucose levels still fell below 2.7 mmol/l (range 2.0 to 2.6 mmol/l) after 16 hours of fasting. However, none had any symptoms. Keywords: Hypertension, Diabetes mellitus, Glucose, Glycolysis

mTOR Inhibitors for the Treatment of Severe Congenital Hyperinsulinism: Perspectives on Limited Therapeutic Success

Context: Congenital hyperinsulinism (CHI) is the most common cause of persistent hypoglycemia in neonates and infants. In medically unresponsive CHI, subtotal pancreatectomy is performed to achieve euglycemia with consequent diabetes in later life. Sirolimus, a mammalian target of rapamycin (mTOR) inhibitor, has been reported to obviate the need for pancreatectomy, but experience is limited. Objective: We have investigated the efficacy and adverse effect profile of mTOR inhibitors in the treatment of severe CHI. Design, Setting, and Patients: This was an observational review of 10 severe CHI patients treated with mTOR inhibitors, in France and the United Kingdom, with the intention of achieving glycemic control without pancreatectomy. Safety information was recorded. Main Outcome Measure(s): We examined whether mTOR inhibitors achieved glycemic control, fasting tolerance, and weaning of supportive medical therapy. Results: mTOR inhibition achieved euglycemia, fasting tolerance, and reduced medical therapy in only three patients (30%). Triglyceride levels were elevated in five patients (50%). One child required a blood transfusion for anemia, four had stomatitis, two had sepsis, one developed varicella zoster, and two patients developed gut dysmotility in association with exocrine pancreatic insufficiency. In silico analysis of transcriptome arrays from CHI patients revealed no significant association between mTOR signaling and disease. Pancreatic tissue from two patients who did not respond to sirolimus showed no reduction in cell proliferation, further suggesting that mTOR signaling did not down-regulate proliferation in the CHI pancreas. Conclusion: mTOR inhibitor treatment is associated with very limited success and must be used with caution in children with severe CHI.

The effect of tailoring of cornstarch intake on stature in children with glycogen storage disease type III

To determine the individual fasting tolerance for patients with glycogen storage disease type III (GSD III) and to assess their linear growth velocity after tailoring of dose intervals of oral uncooked cornstarch.A prospective cohort study included 32 patients with GSD III aged 6 months–11.5 years (median: 3.3 years). The fasting tolerance of each patient was determined as the time interval between starch administration until the drop in blood glucose level was below 60 mg/dL.Some 27 patients (84.4%) developed hypoglycemia. The intervals between oral cornstarch administration were tailored for each child according to his/her individual fasting tolerance. After a 6-month follow up there was a significant reduction in seizure attacks (p<0.01) and liver size (p<0.01), but there was no statistically significant difference in liver transaminase and serum lactate levels. There was a significant improvement in height (p<0.01) and linear growth velocity (p<0.05) of these patients after at least a 12-month follow up.: Adjusting the intervals between the cornstarch doses for each patient with GSD III, according to individual fasting tolerance test was very beneficial and resulted in improvement of the linear growth velocity and reduction in the frequency of hypoglycemic seizures as well as the size of the liver. Individual scheduling of cornstarch doses prevents complications in those who develop hypoglycemia at short intervals; it also allows some relaxation in schedule for those who can tolerate longer fasting hours to improve their appetite and prolong their uninterrupted sleep hours.