The use of complementary and alternative medicine (CAM) is common among type 2 diabetes mellitus (T2DM) patients in Indonesia and may potentially affect adherence to prescribed diabetes medication, leading to uncontrolled blood sugar levels and complications. Aims: The objectives of this study were to analyze the association of CAM use with adherence to prescribed diabetes medication and to identify predictors of low adherence to prescribed diabetes medication. Settings and Design: A cross–sectional survey was done in a secondary health care facility in Bandung city, Indonesia. Data were collected between February and April 2014 from 114 respondents selected through consecutive sampling. Statistical Analysis Used: Chi–square test and ordinal logistic regression were used for statistical analysis. Results: The result showed that 64.9% of the respondents used CAM with herbal products (54.4%), ceragem (16.7%), and massage (12.3%) as the most widely used types. CAM use was found to significantly decrease adherence to prescribed diabetes medication (P < 0.05). The multivariate analysis suggested that the predictors of low adherence were CAM used [adjusted odds ratio (ORadj) 6.16; 2.44–15.52], gender (ORadj2.57; 1.05–6.31), and age (ORadj4.25; 1.53–11.31). Conclusions: CAM use decreased adherence to prescribed medication in T2DM patients. Gender and age were also associated with adherence. Instead of ignoring CAM use among patients, health professionals should have increased awareness and better training about CAM so that they can provide patients with relevant information and assist them in their decision–making regarding CAM use. © 2016 Annals of Tropical Medicine and Public Health|Published by Wolters Kluwer–Medknow.