OBJECTIVE: To determine if changes in overtreatment rates were associated with changes in undertreatment rates. DESIGN: Pre-test/post-test study used cross-sectional administrative data from calendar years (CYs) 2013 and 2016. SETTING: The Veterans Health Administration. PARTICIPANTS: Patients with diabetes at risk for hypoglycemia (n = 171 875 and 166 703 in 2013 and 2016, respectively). INTERVENTION: Observational study of extant initiatives to reduce overtreatment. MAIN OUTCOME MEASURES: Overtreatment rate of diabetes defined at the proportion of patients in the group at high risk for hypoglycemia with A1c < 7.0%. Undertreatment defined as A1C > 9%. RESULTS: There was marked variation in overtreatment rates; for A1c < 7%, overtreatment rates ranged from 26.4% to 58.2% and 26.2% to 49.2% at the facility level in 2013 and 2016, respectively. The mean (±standard deviation (SD)) facility-level overtreatment rates fell from 40.3 (±5.3)% in 2013 to 37.75 (±4.70)% in 2016 (P < 0.001, paired t-test). Facility undertreatment rates ranged from 5.8% to 16.9% and 6.8% to 18.7% at the facility level in 2013 and 2016, respectively. The mean (±SD) undertreatment rate rose from 10.3 (±2.2)% in 2013 to 11.0 (±2.4)% in 2016 (P ≤ 0.001, paired t-test). However, change at individual facilities ranged from a decrease of 4.6% to an increase of 7.2%. Within year correlations were stronger than between year correlations. Overtreatment defined as A1c < 7 in this population inversely correlated strongly with undertreatment (r = -0.653, P < 0.001). CONCLUSIONS: Promotion of overtreatment reduction may be associated with an increase in undertreatment in patients with diabetes. Unintended consequence should be considered when implementing and evaluating quality measures and systems should include balancing measures to identify potential unintended harms.