Polypharmacy is common in patients with a chronic disease. It is appropriate when both the patient and the physician discuss the goal of each prescribed medication with a motivated patient capable of managing his/her medication. It can however be inappropriate when treatment becomes too complex for the frail patient. The risk is non-adherence to therapy, which often results in an intensification of treatment due to unmet therapeutic goals. Collaboration between physicians and pharmacists is therefore essential for the educational support of patients with polypharmacy. In this article, we review the studies examining the impact of a physician-pharmacist collaboration on the medication adherence of diabetic patients with renal impairment.