Drinking of hot spring water containing sulfur or sodium bicarbonate is reported to be beneficial for diabetic patients. In the present study, sulfur spring water and water from simple thermals were chosen to examine their effects on glucose metabolism. Eleven volunteers including eight type 2 diabetic patients and three healthy subjects drank hot spring water from Kawayu Onsen (K-O, acid alum vitriol hydrogen-sulfide springs, pH1.98), and another six patients from Asukano-yu (A-Y, alkaline simple thermals, pH8.9). Oral glucose tolerance test (OGTT) was performed after drinking tap water (200ml) or K-O spring water (5 times diluted) at a week interval (short term effect). Increments in plasma glucose levels were significantly lower (p<0.05) with predrinking of spring water than those with pre-drinking of tap water. To know the long term effect of drinking, patients drank K-O water twice daily for 4 weeks or A-Y water twice daily for a week. Hemoglobin A_1C levels decreased significantly (p<0.05) by drinking K-O water and the levels of 1.5-Anhydro-D-glucitol increased by A-Y water (NS). From these findings, it is suggested that drinking hot spring water from K-O and A-Y is beneficial for diabetic patients if they have no contraindications for drinking these kinds of spring water.