In 12 healthy volunteers [ age ( mean SEM ) 38.3 8.1 years ; body mass index ( BMI ) 21.9 0.8 kg/m ] we studied glucose and insulin responses to oral glucose tolerance test ( OGTT , 75 g ) before and after 15 days treatment with brotizolam 0.25 mg/day or zolpidem 10 mg/day .