Fecal Microbiota Transplantation for Type 2 Diabetes Mellitus and Hashimoto's Thyroiditis

The goal of this clinical trial is to learn if fecal microbiota transplantation (FMT) can improve metabolic control and immune function in adults with both type 2 diabetes and Hashimoto's thyroiditis (an autoimmune thyroid disease). It will also learn about the safety of FMT in these patients. The main questions it aims to answer are: Can FMT lower blood sugar levels (HbA1c, fasting blood glucose, and 2-hour post-meal blood glucose) in participants with type 2 diabetes? Can FMT reduce thyroid autoantibody levels (TPOAb and TgAb) in participants with Hashimoto's thyroiditis? This is a single-arm study, meaning all participants will receive the same FMT treatment. Researchers will compare each participant's results before and after the intervention to see if FMT has an effect. Participants will: Complete baseline tests including blood work and stool sample collection during the 2-week screening period Take 40 oral FMT capsules by mouth over about 1.5 hours under medical supervision at the start of the study Keep taking their usual diabetes and thyroid medications at the same dose throughout the study, unless their doctor says otherwise Return for follow-up visits and tests at 12 weeks and 24 weeks after the FMT treatment