We have recently shown, in studies with patients with Type 1 (insulin dependent) diabetes, that alcohol intake at 2100 hrs significantly reduced blood glucose values after 10-12 hours, compared with control studies with no alcohol. We hypothesised that this was due to the following effects of alcohol: 1. Alcohol metabolism increases NADH, leading to a reduction in hepatic gluconeogenesis; and 2. increased glycogen phosphorylase activity depletes hepatic glycogen stores; 3. After the alcohol is metabolised, hepatic insulin sensitivity is increased, leading to the restoration of glycogen stores and reduction in blood glucose levels, and 4. consequently, after several hours, glycogen stores and insulin sensitivity return to normal. A model describing these changes (DiasNet-Alcohol) was implemented into the DiasNet model of human glucose metabolism. Our study suggests that the DiasNet-Alcohol model gives a reasonable approximation of the effect of alcohol on blood glucose concentration observed in our study and supports our hypothesis for the mechanism behind these effects in Type 1 diabetes.