The majority of women with polycystic ovary syndrome (PCOS) have insulin resistance (IR) and have a high risk of developing diabetes. In this retrospective study of women with PCOS, Implanon use was associated with increased insulin resistance, as evidenced by a deterioration in the homeostasis model assessment (HOMA) assessment of insulin resistance, and increased fasting insulin levels. Implanon might increase the risk of diabetes and potentially cardiovascular disease in this already high-risk group. Further research is required to establish the ideal contraceptive preparation in PCOS.