Disclosed are a prophylactic or therapeutic agent for a diabetic disease having little adverse side-effects and a functional food or food material for the prevention or amelioration of a diabetic disease, both of which can ameliorate a diabetic disease such as hyperglycemia, diabetic hyperlipemia and diabetic osteoporosis. The prophylactic or therapeutic agent or the functional food or food material comprises, as an active ingredient, a special salt "Sal de Tierra" which can be produced by contacting a natural ion exchanger with any one selected from an aqueous sodium salt solution, an aqueous potassium salt solution, an aqueous calcium salt solution, an aqueous magnesium salt solution, aqueous ammonia, an aqueous ammonium salt solution, an aqueous inorganic acid solution, an aqueous organic acid solution, sea water, a saline lake water and a hot spring water to cause the elution of a component contained in the natural ion exchanger from the natural ion exchanger by ion exchange, and then separating an eluate from the natural ion exchanger.
