ABSTRACT Management of pharmacotherapy in elderly with metabolic diseases is challenging and potentially inappropriate medications (PIMs) are risk factors for drug interactions and adverse events. The exposure to PIMs in elderly outpatients with metabolic diseases and its relationship with polypharmacy and other variables was investigated. PIMs prescribed to 207 elderly patients (aged 60 to 96 years) with metabolic diseases who attended a University Hospital of Sao Paulo city, Brazil, from April/2010 to January/2011, were evaluated. PIMs were detected using both 2003 Beers and 2008 STOPP criteria. The association between PIMs and age, gender and polypharmacy was also examined. 2008 STOPP criteria detected more PIMs (44.4 %) than 2003 Beers criteria (16.0%, p<0.001). Beers detected mainly PIMs antihypertensive (clonidine, 20.0%; doxazosin, 10.0%) and antidepressant (fluoxetine, 15.0%; amitriptyline, 10.0%) PIMs. Medicines used for cardiovascular (aspirin, 53.7%) and endocrine system (glibenclamide, 21.3%) were PIMs more frequently detected by 2008 STOPP. Unlike age and gender, polypharmacy increased the risk of PIMs by both 2003 Beers (OR: 4.0, CI95%: 1.2-13.8, p<0.031) and 2008 STOPP (OR: 6.8, CI95%: 3.0-15.3, p<0.001). Beers and STOPP criteria are important tools to evaluate the exposure to PIMs, which is strongly associated with polypharmacy in elderly outpatients with metabolic diseases.