Integrated behavioral healthcare (IBH) is the “standard of care” to address psychosocial factors impacting diabetes outcomes; it is not standard in practice. This longitudinal, retrospective, chart-review examines IBH impact on glycemic control in an adult diabetes clinic. Adults (n = 374) with ≥ 1 behavioral health encounter, ≥ 2 hemoglobin A1c (HbA1c) values, and HbA1c value > 8% at initial IBH visit were included. Mixed effects linear piecewise models examined differences in slope trajectories for 365 days pre- and post-IBH intervention. Pre-intervention slope was not significant (z = − 1.09, p = 0.28). The post-intervention slope was significant (z = − 6.44, p < 0.001), indicating a significant linear decrease in HbA1c values. Results demonstrated that prior to engaging with behavioral health, there was no change in HbA1c. After initial IBH visit, there was a predicted reduction of > 1% in HbA1c over the following year. These results suggest that IBH significantly improves patients’ metabolic status. Next steps for IBH research are offered.