Insulin acts to help glucose into cells but it's presence also acts to stop too much glucose being released from the liver. The diagram on this link helps to explain what insulin does.
http://biomed.brown.edu/Courses/BI108/B ... ucagon.htm
As you can see the liver plays an important role in releasing glucose when needed and insulin helps to control this release. It can also manufacture 'glucose'.
There are several possible problems that can lead to hypos, all to do with the liver.
1)Alcohol is metabolised in the liver. You can process about 1u an hour. Whilst this is going on the liver doesn't make any glucose .This may be a problem If someone hasn't been eating for a while (or has exercised) as their stores of glucose may be very low
this applies to non Ds as well and malnourished alcoholics can suffer from hypos
2) Alcohol makes the liver more sensitive to insulin ie you need less. If you have too much injected insulin present it may act to prevent the release of glucose.
3) The mechanism that releases glucose at very low blood glucose levels may also not work well in people with T1.
4) The behaviour altering effects of too much alcohol can also cause a person to be unaware of their normal hypo feelings and so not treat in good time to prevent glucose falling further.
5) There is an increased risk of hypos the next day; probably because glucose reserves have been used up and not fully replaced.
Sounds dreadful but basically it means that you have to take care, drink moderately and try to eat something whilst drinking.
