To the Editor: Prolonged hypoglycaemia in patients taking a sulfonylurea may be refractory to intravenous glucose treatment with fatal consequences, as described by Veitch and Clifton-Bligh.1 Although these authors briefly mention the use of octreotide, we believe that an additional point in the “Lessons from practice” should have been: Octreotide may be an effective therapy in refractory sulfonylurea-induced hypoglycaemia.

We describe the first two patients in whom we used this therapy.

A 76-year-old man with type 2 diabetes was admitted after an acute myocardial infarction and cardiac arrest. He was successfully resuscitated and underwent emergency bypass surgery. His diabetes was controlled with gliclazide 80 mg twice a day. After surgery, he developed cardiac failure, renal impairment (serum creatinine level, 0.22 mmol/L) and frequent hypoglycaemic episodes. The gliclazide was stopped but, despite good oral dietary intake, hypoglycaemia worsened and failed to respond to vigorous intravenous glucose therapy. He suffered a hypoglycaemic seizure (blood sugar level, 0.8 mmol/L). Over the next day, he received more than 300 g of glucose in the form of a 10% glucose intravenous infusion, but, despite this, went into hypoglycaemic coma. Blood results were: insulin, 472 pmol/L (reference range [RR], 15–60 pmol/L); C-peptide, 7616 pmol/L (RR, 300–800 pmol/L); and gliclazide, 9.4 mg/L (steady state average, 2.5 mg/L). He was given an intravenous infusion (30 ng/kg per minute) of octreotide.2 Within an hour, his blood sugar level rose to 7.9 mmol/L and continued to rise. Dextrose and octreotide infusions were ceased within 13 hours, with no further episodes of hypoglycaemia. He was discharged home 2 days later.

A 75-year-old man with type 2 diabetes was taking glibenclamide 2.5 mg each morning. He was transferred from a rural hospital with acute on chronic renal failure (serum creatinine level, 0.4 mmol/L), as well as recurrent hypoglycaemia. The glibenclamide was stopped, but blood sugar levels remained low, and he became comatose despite boluses of 50% dextrose and a continuous infusion of 10% dextrose. The high volume of intravenous fluid precipitated cardiac failure and pulmonary oedema, requiring inotropic support. Blood results were: blood sugar, 1.5 mmol/L; insulin, 1250 pmol/L; C-peptide, 20 949 pmol/L. As an alternative to the high-dose, continuous infusion of octreotide used in our first patient, we administered a single subcutaneous injection of octreotide 50 μg. One hour later, the patient’s blood sugar level had risen to 9.0 mmol/L. He had no further episodes of hypoglycaemia. Eight hours later, insulin and C-peptide levels had fallen markedly (insulin, 153 pmol/L; C-peptide, 5654 pmol/L). He made a full recovery.

Octreotide is a somatostatin analogue that inhibits the secretion of a number of neuropeptides, including insulin. It is a safe and effective therapy for sulfonylurea-induced hypoglycaemia when initial therapy with oral or intravenous glucose fails.2-5 It is particularly useful in elderly patients with renal or cardiac complications, in whom fluid overload may be a limiting factor in intravenous dextrose therapy. Octreotide may also break the vicious circle that can occur in sulfonylurea-induced hypoglycaemia in which repeated dextrose boluses further stimulate insulin release.

In reply: Crawford and Perera highlight a very important point with respect to hospital-based treatment of sulfonylurea-induced hypoglycaemia. Whereas, in our article,1 we wished to emphasise the importance of recognising and preventing this condition in primary care settings, we agree that octreotide is an effective therapy in treating this condition. Octreotide inhibits the specific effect of sulfonylureas (glucose-stimulated β-cell insulin release) and prevents rebound hypoglycaemia, which, in this situation, may occur with the use of glucose.2 Case reports, including those elegantly presented and referenced by Crawford and Perera, clearly illustrate the safety and efficacy of octreotide in treating sulfonylurea toxicity when initial therapy with glucose fails. Octreotide may be administered either intravenously or subcutaneously, and its effect is maintained after a short course of therapy.

At our own institution, we have now adopted guidelines for the treatment of refractory sulfonylurea-induced hypoglycaemia, which include the administration of octreotide (50 μg subcutaneously) every 8 hours for up to three doses, although, as Crawford and Perera note, some patients will have a sustained response after a single dose.