Effect of alcohol on blood glucose levels

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What is the effect of alcohol on blood glucose levels?

When I run education classes for type 1 and type 2 diabetes I always talk about the effect of alcohol on blood glucose levels. This is an important subject but an often ignored one. When I mention alcohol in my medication sessions, suddenly everyone seems to perk up – god knows why :).

During the education sessions I ask patients to sort food models from all the food groups into 3 categories. 1) contains carbohydrate, 2) does not contain carbohydrate or 3) unsure. This is because it is carbohydrates that effect glucose levels. If you need more information about this, you can find it here. 

Most of the time, patients place alcohol in the incorrect place or place it the unsure pile. It is assumed the effect of alcohol on blood glucose levels is like lighting a match to a canister of petrol. Yet the reality is much different. With this in mind, I thought it might be a good idea to offer a blog on the subject.

What is alcohol

Drink aware defines alcohol as the following:

“The type of alcohol in the alcoholic drinks we drink is a chemical called ethanol. To make alcohol, you need to put grains, fruits or vegetables through a process called fermentation. Fermentation is when yeast or bacteria react with the sugars in food – the by-products are ethanol and carbon dioxide).

Wine and cider are made by fermenting fruit, while fermented cereals such as barley and rye form the basis of beer and spirits.

A drink’s alcohol content is affected by how long it’s left to ferment.

Spirits also go through a process called distillation – where a proportion of the water is removed, leaving a stronger concentration of alcohol and flavour”.

Alcohol is actually one of our 4 macronutrients alongside carbohydrate, protein and fat. These are the energy providing nutrients. Carbohydrate and protein provide 4kcal/g, fat provides 9kcal/g and alcohol 7kcal/g (this is just pure alcohol). We are generally sceptical of calling alcohol a nutrient though because in terms of nutrition it provides very little.

For what it lacks in nutrition it seems to make up for in fun and therefore I don’t see alcohol going anywhere in the near future. Therefore, it is something certainly worth addressing with patients.

Alcohol and diabetes

Primary considerations vary depending on the type of diabetes you are dealing with. First let’s look at the effect of alcohol on blood glucose levels and then apply this to the different types of diabetes.

Alcohol in its pure form actually reduces blood glucose levels. How can this be patients often ask through big smiling grins?

The reason is actually quite logical. The liver usually releases a steady stream of glucose into the system to provide the body with a regular energy source. The liver also breaks down alcohol. Unfortunately, it can’t do two things at once. So when breaking down alcohol, the liver stops producing the steady stream of glucose into the system.  Therefore, your internal supply of glucose is stopped. Glucose levels consequently start to drop. Clearly multitasking is not the livers strength.

Types of drinks and effect on glucose levels

Not all alcoholic drinks will have the same effect on blood glucose levels. Beers, ciders and alcopops tend to have a variety of additional carbohydrate added to them whereas spirits and dry wines have very little or no carbohydrate.

So when you drink beer, cider or sugary alcohol drinks, you’ll see an initial rise in blood glucose levels. Once you absorb the carbohydrate you will be left with only the alcohol remaining in your system and blood glucose levels will begin to decline. This effect will depend on the amount of alcohol you are drinking.

Type 1 diabetes and/or those taking insulin

Anyone taking insulin needs to be considerate of their alcohol intake. We now know alcohol pushes blood glucose levels down. Insulin also reduces blood glucose levels. We therefore get a double effect. This can leave those taking insulin more prone to hypoglycaemia. A particular worry with this is we tend to drink at night and therefore many potential hypo’s may occur overnight.

If you drink anywhere near like I did in my 20’s, you may not wake up or notice the hypo. This leaves you at risk of suffering a severe hypo.

People drink in various scenarios but here are a 2 to consider and how to manage your insulin around them.

Night out with drinks

First, do not take insulin for alcoholic drinks. If you like beer, cider or sugar alcoholic drinks, it might be better to accept a higher reading at first safe in the knowledge the glucose levels will likely decline later.

As time goes on you’ll establish patterns on how alcohol effects you and you can begin to develop management plans accordingly.

Some patients may take a small correction dose if their glucose levels rise substantially but they will not take a full correction, perhaps around 30%.

One of the main pieces of advice we give is to ensure you have a carbohydrate containing snack before going to bed. For the kebab lovers out there, this too is good news!

Meal out

Eating out over a few drinks can be a sociable event. You may want to consider reducing the amount of insulin you give if you are having a few drinks over dinner. Particularly with dry wines or spirits with diet mixers. Alternatively, you may consider reducing any corrections you would normally give as above.

Again, over time you will see patterns emerge regarding how your glucose levels respond and you can act accordingly.

Type 2 diabetes and/or those not taking insulin

One other class of medication exists that we tend to be concerned about with hypo’s. Sulphonylureas (Glibenclamide, Gliclazide, Glipizide, Glimepiride, Tolbutamide) squeeze more insulin out of the pancreas and therefore can leave you susceptible to hypos. Ensure you have a snack after drinking if taking these medications.

If you’re not taking any sulphonylureas, alcohol will still reduce your blood glucose levels but not leave you prone to a hypo. I should stress this isn’t a reason to increase your alcohol intake suddenly (sorry).

Those taking an SGLT-2 tablet (the ones ending in gaflozin) should also practice caution with alcohol. This class of tablets make you wee out the excess sugar in your system leaving you prone to dehydration. Alcohol is a diuretic and can dehydrate you. Dehydration in diabetes is never a good thing. First, it can leave you prone to urinary tract infections. Second, due to the concentration of glucose in the blood when dehydrated, it can push blood glucose levels up.


Type 2 diabetes is a disorder of how well your body can manage it’s glucose levels. This fact does not change without some significant lifestyle intervention.

Drinking may push blood glucose levels down but it only hides what is truly happening in the body.

Most alcoholic drinks are very high in calories and may lead to weight gain. People carrying too much weight are more prone to developing Type 2 diabetes. So eating and drinking high calorie food will not help the condition long term.

Think almost of every alcoholic drink as being the equivalent of a mini dessert. So enjoy a drink but it is best if enjoyed in moderation.

Safe drinking

You didn’t think we would get through the whole blog without me making some reference to safe drinking recommendations. Typical dietitian I know.

Frequent and excessive alcohol intake can lead to multiple health problems. People drinking excessive amounts of alcohol regularly have been shown to be at an increased risk of developing health problems. Particularly those of the liver, kidney and cardiovascular system amongst many other conditions.

In the UK the recommend weekly limit is to not regularly exceed 14 units per week for men and women with at least 2 alcohol free days per week.

Typically a pint of beer or cider equates to 2-3 units, a medium glass of white wine is 2-3 units and a single spirit measure equals 1 unit.

I mentioned excessive drinking there. This word excessive is a good one to emphasise because by definition excessive drinking is exceeding the above recommendation. I see a lot of patients who wouldn’t consider the above excessive. However, drinking above 14 units per week is the level where the risk of damaging your body is increased and thus considered excessive. So just be cautious.


Hopefully this overview is a good starting point. If you are type 1, the important thing is to try to test your glucose levels reguarly around drinking alcohol to help establish patterns. I know this may not always be practical if having a particularly heavy session but do your best.

Alcohol intake and scenarios of alcohol consumption will vary from person to person. Therefore, your response to alcohol will differ from the next person. What is important is understanding how it effects your glucose levels.

If type 2, be careful with how much you drink. The calories contained in alcohol will not help the disease long term because 90% of people suffering with type 2 diabetes need to lose weight.

Regardless of your type of diabetes, regular alcohol consumption can also lead to health complications and so drinking is best kept to a minimum.

Need more help

If you need more support we offer a range of 1:1 consultancy services and online programmes focused on helping you improve your glucose control and health for the long term. These include our type 2 diabetes recovery programme, type 1 glucose stability programme and winning weight loss programme. Go to the pages using the links above or in the headers or get in touch if you have questions.

3 thoughts on “Effect of alcohol on blood glucose levels”

  1. I’m impressed, I must say. Seldom do I come across
    a blog that’s both equally educative and entertaining,
    and without a doubt, you have hit the nail on the head.
    The problem is something which not enough men and women are speaking intelligently about.

    I’m very happy that I stumbled across this in my search for something relating to this.

  2. What’s up, just wanted to tell you, I liked this article.

    It was funny. Keep on posting!

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