What does alcohol do to your blood sugar and insulin sensitivity?

Alcohol has opposing effects on your blood sugar, depending on when and how much you drink. On an empty stomach, alcohol inhibits the liver in two key processes: producing new glucose and releasing stored glucose. The result can be dangerously low blood sugar, especially if your glycogen stores are already depleted or if you are taking blood-sugar-lowering medications such as sulfonylureas.

With a carbohydrate-rich meal, the effect reverses. Your body burns alcohol as fuel before the carbohydrates, which can cause blood sugar to run temporarily higher. A blood sugar dip may follow, and how pronounced it is depends on what you have eaten. This applies in particular to people with type 2 diabetes.

Light to moderate drinking has been linked in observational research to better insulin sensitivity and a lower risk of type 2 diabetes. Whether this reflects a true cause-and-effect relationship is not certain; it may also be tied to other lifestyle factors. Heavy drinking flips this picture entirely: it seriously disrupts blood sugar regulation and cancels out any beneficial effect.

In children with acute alcohol poisoning, the effects on blood sugar are unpredictable. Forty percent had elevated blood sugar, yet low blood sugar is also well documented. This underlines that acute alcohol poisoning requires medical monitoring.

There is also evidence from large genetic population studies that certain gene variants determine how strongly alcohol influences glucose metabolism. This is an interesting scientific finding, but for now it says nothing practically useful about what you personally can expect.