Refining metformin prescribing in New Zealand.

Metformin is the mainstay of treatment of type 2 diabetes. However, there has been significant concern on prescribing metformin in patients with renal impairment as a result of metformin-associated lactic acidosis (MALA). Recent studies have cast doubt on the existence of MALA purely related to metformin use. Medsafe recently initiated changes to datasheet so lower doses of metformin could be used in patients with GFR down to 15ml/min. In this paper we outline the context and implications of this change.