Blood samples (~ 18ml) will be taken prior (t = -3 minutes) to the drink and then at t = 30, 60, 90, 120 and 180 minutes for the subsequent measurement of blood glucose, serum insulin and incretin hormones. Samples will be stored at -70°C until analysed. Blood glucose will be determined immediately using a portable glucometer (Medisense Companion 2 meter, Medisense Inc, Waltham, USA).