Letters

Contraindications to use of metformin

BMJ 2003; 326 doi: http://dx.doi.org/10.1136/bmj.326.7392.762/a (Published 05 April 2003) Cite this as: BMJ 2003;326:762

Age and creatinine clearance need to be taken into consideration

  1. Andrew T Elder, consultant physician ([email protected])
  1. Western General Hospital, Edinburgh EH4 2XU
  2. Department of Obstetrics, University of Adelaide, Queen Elizabeth Hospital, Woodville, SA 5011, Australia
  3. Department of Medicine, Gold Coast Hospital, University of Queensland, Southport, QLD 4215, Australia
  4. Department of Physiology, School of Medicine, Flinders University, Bedford Park, SA 5042, Australia
  5. National Women's Hospital, Auckland, New Zealand
  6. Barts and the London NHS Trust, London E1 1BB
  7. Department of Diabetes, Gartnavel General Hospital, Glasgow G12 0YN
  8. Diabetes Centre, Western General Hospital, Edinburgh EH4 2XU

    EDITOR—Jones et al criticise current guidelines highlighting possible contraindications to the use of metformin as too vague and potentially leading to underuse in patients with type 2 diabetes.1 Although their desire for a “less ambiguous” approach seems sensible, their own guidelines still lack clarity.

    They note that any specific value of serum creatinine concentration chosen as a cut-off point for prescribing metformin will be arbitrary because of variations in muscle mass and protein turnover. Despite this they then select—for undefined reasons—a serum creatinine value of 150 μmol/l as the cut-off point in their guideline. They then say that caution should therefore be used in prescribing metformin for elderly patients.

    This is a vague statement, which could be interpreted as meaning that metformin should not be prescribed at all for elderly people, that specialist opinion should be sought or creatinine clearance calculated before it is prescribed, or that renal function or serum lactate concentration should be monitored after it is prescribed.2 In addition, the authors do not define elderly.

    Given that the growing majority of patients with type 2 diabetes are over 65 and that there is already evidence of undertreatment in such patients,3 it seems particularly desirable to be as clear as is possible about this age group if the full benefits of treatment are to be attained.

    Although the …

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