Drug points: Rapidly reversible increase in insulin requirement with interferon

BMJ 1996; 313 doi: (Published 13 July 1996) Cite this as: BMJ 1996;313:92
  1. Stewart Campbell,
  2. E H Mclaren,
  3. B J Danesh

    We report a case of a 66 year old man with maturity onset diabetes who developed a rapidly reversible increase in insulin requirement while receiving interferon alfa 2a for hepatitis C.

    The patient's diabetes had been well controlled for three years on a total of 62 units of Mixtard daily (glycosylated haemoglobin 7-9%). His other medications were spironolactone 100 mg twice daily and bumetanide 1 mg daily.

    After three months of treatment with interferon alfa, 5 000 000 U subcutaneously three times weekly, his blood glucose concentration was 50.4 mmol/l, necessitating a progressive increase in his insulin dose. After six months of interferon treatment he was admitted to hospital with vomiting, anorexia, and dehydration. He was then receiving a total of 118 units of Mixtard daily. Interferon was discontinued, as there was no change in his liver function values during treatment (table 1). Within eight days his insulin requirement had fallen to 24 units Mixtard daily. Subsequent follow up showed only a modest increase in insulin requirement to 28 units Mixtard daily.

    Table 1

    Liver function values during and after treatment with interferon alfa for hepatitis C

    View this table:

    Autoimmune phenomena during treatment with interferon alfa are well recognised. Development of insulin dependent diabetes with seroconversion for islet cell antibodies during interferon alfa therapy for hepatitis C has been reported.1 However, impaired glucose tolerance during treatment with interferon alfa has also been shown in healthy subjects2 and in a patient with chronic hepatitis B3; in these cases an autoimmune mechanism is less likely.

    To our knowledge this is the first reported case of an increase in insulin requirement associated with interferon alfa therapy which was rapidly reversible on withdrawal of interferon. This suggests that impaired glucose tolerance rather than an autoimmune phenomenon explained the increase. We recommend that in patients with chronic liver disease and diabetes or impaired glucose tolerance interferon alfa should be used with caution and blood glucose monitored regularly.—STEWART CAMPBELL, E H MCLAREN, B J DANESH, Department of Medicine, Stobhill NHS Trust, Glasgow G21 3UW


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