Study on the Molecular Mechanism of Berberine to Improve Type 2 Diabetes Mellitus Complicated With Depression

This study is investigating the molecular and gut microbiome effects of berberine (a plant-derived compound used in traditional Chinese medicine) in people who have both type 2 diabetes and depression. Researchers want to understand how berberine may affect gut bacteria and brain chemistry. **You may be eligible if...** - You are between 18 and 65 years old - You have been diagnosed with type 2 diabetes - You are either in the control group (diabetes without depression) or the patient group (diabetes plus depression, with a HAMD-17 score of 22 or above) - You have signed an informed consent form **You may NOT be eligible if...** - You have taken antibiotics, probiotics, or similar gut-affecting supplements in the 3 months before the study or plan to take them during it - You have a serious progressive illness such as active cancer - You have used psychotropic medications within the past month - You are pregnant or breastfeeding - You have alcohol or substance dependence Talk to your doctor to see if this trial is right for you.