Editor, – Regarding insulin and metformin schedules - indeed one size does not fit all. Dr Pat Phillips' excellent update 'Insulins in 2002' (Aust Prescr 2002;25:29-31) nicely highlights inter-individual insulin requirements (e.g. a predicted daily range of 39 to 78 units of insulin for a 78 kg man).
When metformin is factored into the equation, the considerations become even more complex, as when for example a patient has mild diabetes-related renal dysfunction and/or chronic low-grade hepatitis B, both of which are relative contraindications to the use of metformin.
I am also currently looking after a man in his 70s who is mildly overweight, with borderline urea and creatinine, chronic hepatitis B with a slightly raised GGT but normal ALT concentration. His insulin requirements exceed 100 units per day, but metformin is being withheld out of concern for potential adverse effects.
In view of the potential value of metformin with insulin, would Dr Phillips care to comment further on the nuances of this interesting combination of drugs?
Ross Philpot
Consultant Physician
Adelaide