CATIONS TO METFORMIN THERAPY IN PATIENTS WITH NIDDM

OBJECTIVE - Treatment with metformin is occasionally associated with t he development of severe lactic acidosis. However, this is usually obs erved in patients with major contraindications to the drug. In this st udy, we aimed to determine the prevalence of conditions currently rega rded as either contraindications or cautions to the use of metformin i n patients with NIDDM. RESEARCH DESIGN AND METHODS - The case notes of metformin-treated NIDDM patients (mean age 62 years) attending a Unit ed Kingdom university hospital diabetes clinic over a 3-month period w ere reviewed according to criteria reflecting a pragmatic view of curr ent prescribing recommendations. RESULTS - Of 89 consecutive patients whose notes could be evaluated in detail, only 41 (46%) had no contrai ndications or cautions to metformin whatsoever. Concomitant chronic di sorders associated with a potentially increased risk of hyperlactatemi a were renal impairment (n = 2; plasma creatinine concentrations 1.7 a nd 2.3 mg/dl, respectively), cardiac failure (n = 2), and chronic live r disease (n = 2). Other potentially relevant disorders included ische mic heart disease (n = 20), clinical proteinuria (n = 14), peripheral vascular disease (n = 22), and pulmonary disease (n = 7). Multiple con ditions (i.e., two, three, or four) were present in eight, five, and o ne patient(s), respectively. CONCLUSIONS - More than half the patients in our series had concomitant conditions or complications conventiona lly regarded as cautions or contraindications to metformin; similar to 10% had a multiplicity of such conditions. Regular surveillance is ne cessary to detect the development of complications such as renal impai rment. Vigilance is also required in view of the increased risk of maj or intercurrent illnesses, which may independently disturb lactate met abolism in patients with NIDDM. Metformin should be withdrawn promptly under such circumstances.