In some circumstances the hypoglycemic stimulus is so powerful that an infusion of glucose alone is insufficient to restore normoglycemia. This can occur with insulin-secreting tumors. Additional therapeutic measures in these circumstances are aimed at reducing endogenous insulin production and promoting gluconeogenesis.
Diazoxide is related to the thiazide diuretics, emphasizing the inhibition of insulin secretion by b-cells but interestingly causing salt and water retention. It has powerful vasodilator activity, causing reflex tachycardia. An infusion of 3 to 8 mg/kg/day in 5 per cent glucose or a bolus of 30 to 300 mg intravenously are suggested dosages.
Somatostatin and its longer-acting analog octreotide are often used for resistant hypoglycemia caused by insulinoma. However, these drugs have variable effects on gut hormone release and can cause a fall in blood glucose in some patients. Their use should be closely monitored with serial blood glucose measurements.
Glucocorticoids bind to intracellular receptors and alter protein and receptor synthesis to exert their multiple pharmacodynamic effects, of which stimulation of gluconeogenesis, muscle catabolism, and lipolysis all act to increase blood glucose. Intravenous administration of hydrocortisone 100 mg every 6 h is a useful adjunct that may help in resistant hypoglycemia.
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