There are 2 basic kinds of diabetics. Knowing which is important. Type 1 must have insulin since their body can't/won't make it. Type 2 has a cellular problem where their body makes insulin, but their cells forget how to use it. Adding more insulin can help, but only for a limited number of years.
As said above, alcohol is a carbohydrate. It's not just sugar, but all carbohydrates that are of concern.
In a type 1, they need to calculate the right amount of insulin to take to go with the alcohol/sugar.
A type 2 has things a bit more complicated! There are different needs within the type 2 group. Some can drink and be fine. Others can not. Early stage type 2 is usually OK. Late stage 2 may have kidney damage, and that means alcohol has other issues for them beyond just diabetes.
Here's the fun part. ;-) The liver and kidneys work together to breakdown the alcohol to glucose for the cells and then dispose of the rest. So, if all is healthy there, drinking a couple glasses of mead will actually lower blood sugar levels for a while. This is why some people think it's OK to drink dry alcohol but not sweet. It's a side effect that is good and bad.
The key is knowing your own body and tracking the blood sugar level before, during, and after drinking. From there you can make an educated decision if your body can handle it or not.
I won't tell anyone else what to do about their diabetes, but I will share the facts. For me, drinking every now and then is acceptable. But, I know each drink presents real long term risks. Some day I may not be able to anymore. Then again, I live by the rule it's better to burn out than fade away!