OBJECTIVES: This study describes the relationship between health-related quality of life (HR-QoL) assessed using the SF-36v2 and adherence as measured by the Morisky Medication Adherence Scale (4-item MMAS-4 , 8-item MMAS-8, and a 4-item scoring of the MMAS-8) among US adults with type 2 diabetes (T2D).  METHODS: Data were taken from the 2011 and 2012 US National Health and Wellness Survey (NHWS).  The NHWS is a large cross-sectional survey representative of the total adult population in several major markets; N~75,000/year in the US. A total of 13,007 respondents self-reported physician diagnosis of T2D and were administered MMAS-4 in 2011 or MMAS-8 in 2012. The relationship between SF-36v2 measures and adherence was described for the two adherence scales and also a scoring of the MMAS-8 that uses only the 4 items best matched to the questions in the MMAS-4. RESULTS: In T2D patients, MMAS-4 resulted in a greater percentage of respondents classified as having high adherence than MMAS-8 (64% vs. 44%) and a lower percentage of low adherence (3% vs. 19%), while medium adherence was fairly similar (33% vs. 37%). The 4-item scoring of the MMAS-8 was more similar to MMAS-4 (79% high, 15% medium, 6% low). In OLS regressions controlling for sociodemographic characteristics (e.g. age, gender, comorbidities, education, income), all measures of adherence were significant predictors of HR-QoL, with two main differences: R-squared values were slightly lower for regressions including MMAS-4 adherence and MMAS-4 was not predictive of Physical Component Summary (PCS) scores. CONCLUSIONS: All three adherence scores are significantly correlated with the Mental Component Summary and SF-6D health utility scores of the SF-36v2, MMAS-4 fails to correlate with PCS. The variation in proportion of patients classified as highly adherent across scales also suggests pooling such classifications across data using different versions of the MMAS is not advisable, at least among T2D patients.