Medication adherence is often lower among disadvantaged patients. Drivers of medication adherence may include the quality of communications between patient and medical caregiver. The research objective is to assess whether an annual Comprehensive Wellness Assessment (CWA) is associated with improved medication adherence. The CWA targeted primarily dual eligible Special Needs Plan (SNP) enrollees in a Medicare Advantage plan. This retrospective panel study used administrative claims data and member-month level data for members who were newly diagnosed with diabetes in 2010, allowing for up to 5 years of follow-up. The intervention of interest is whether the member received a CWA in the past 12 months. Multivariate regression models were estimated using pooled member-month data and a difference-in-difference type approach to assess whether CWA visits improve oral diabetes medication (ODM) adherence among SNP enrollees. Twenty-six percent of pooled member-month observations are from SNP enrollees. Average monthly ODM adherence is 77.5%. Approximately 31% of SNP enrollees had a CWA in the last 12 months, compared to 5% of regular enrollees. Regression results show SNP enrollees with a CWA on average had higher monthly adherence by 3.9 percentage points (P < 0.01), and were 7% more likely to meet the threshold of at least 80% adherence (P < 0.01). Adherence is even higher for the subsample of African American SNP enrollees with CWA. CWA appears to be effective in improving ODM adherence among SNP patients. Care models with components like wellness assessments that include medication review and education may improve medication adherence as well as Medicare Advantage plan star ratings.