Depression frequently coexists with type 2 diabetes mellitus (T2DM), yet the impact of changes in physical activity following diagnosis remains unclear. A nationwide cohort study published in Diabetes & Metabolism Journal evaluated whether shifts in physical activity levels before and after a new T2DM diagnosis influence subsequent depression risk.

Using data from the National Health Insurance Service of South Korea, investigators identified 254,619 individuals newly diagnosed with T2DM between 2009 and 2015 who had health examination data within two years before and after diagnosis and no prior history of depression. Physical activity was quantified using the metabolic equivalent of task (MET) method.

Compared with individuals reporting 0 MET-min/wk before diagnosis, those who increased activity to 500-999 MET-min/wk after diagnosis experienced a 23% lower risk of depression, while those reaching ≥1,000 MET-min/wk had a 25% lower risk. In contrast, individuals with 1-499 MET-min/wk before diagnosis who became inactive had a 25% higher risk of depression. Similar increases in risk were observed among those who reduced activity from 500–999 or ≥1,000 MET-min/wk.

Changes in physical activity before and after T2DM diagnosis were associated with differences in depression risk. Increased activity corresponded to lower risk, whereas decreased activity corresponded to higher risk.