This study evaluates the safety and preliminary efficacy of Bletilla formosana (BF), a traditional herbal medicine, in adults with prediabetes. Prediabetes is a high-risk condition where blood sugar levels are elevated, often leading to type 2 diabetes. While lifestyle changes are the standard treatment, researchers are exploring herbal supplements as a complementary way to support metabolic health. Preclinical research has shown that BF possesses anti-inflammatory properties and may help regulate blood glucose. Participants in this study will be randomly assigned to receive either a high dose of BF, a low dose of BF, or a placebo (an inactive substance) for 12 weeks. The total study duration is approximately 24 weeks, involving four clinic visits for blood tests and safety monitoring to see how BF affects blood sugar markers and inflammation.