When you consume alcohol, your liver will prioritise processing the alcohol before anything else, including glucose. This means that if you're following a ketogenic diet and your liver is busy metabolizing alcohol, it may result in a temporary drop in blood glucose levels.
Normally, the liver helps to regulate blood glucose levels by producing and releasing glucose as needed. However, when alcohol is present, the liver will switch its focus to metabolising the alcohol instead of producing glucose. As a result, blood glucose levels may drop, which can be dangerous for individuals with diabetes or other blood sugar related conditions.
Additionally, alcohol can also interfere with the normal process of gluconeogenesis, which is the process by which the liver produces glucose from non-carbohydrate sources. This can further contribute to a drop in blood glucose levels on a ketogenic diet.