The invention relates to a Chinese traditional patent medicine (the trade name being Rehmanniae Diabetes Capsule) for treating diabetes. The medicine comprises the following raw materials by weight portion: 30 to 60 portions of dwarf lilyturf tuber (also named dwarf lilyturf root), 30 to 60 portions of asparagus root (also named asparagus), 40 to 70 portions of figwort (also named radix scrophulariae), 70 to 150 portions of coptis root, 50 to 100 portions of oriental waterplantain rhizome, 20 to 50 portions of tuckahoe, 70 to 150 portions of cortex lycii radicis, 50 to 100 portions of tragacanth (also named radix astragali), 40 to 100 portions of cornus (also named cornus pulp), 30 to 60 portions of medlar, 50 to 100 portions of dry rehmanniae (also named fresh rehmanniae), 40 to 90 portions of prepared radix rehmanniae (also named prepared rhizome of rehmanniae), 20 to 60 portions of trichosanthin, 30 to 80 portions of panax, 20 to 40 portions of pilose antler and 50 to 100 portions of white muscardine silkworm. The Chinese traditional patent medicine plays a role in enhancing the sensibility of human body against insulin, reducing blood sugar and blood fat, regulating viscera and nourishing liver and kidney; moreover, the Chinese traditional patent medicine has scientific manufacturing process and can extract effective ingredients in raw materials.