How Alcohol Impacts Blood Sugar

by Jessica Pyhtila, PharmD, BCPS, BCGP

When you have diabetes, it is important to pay attention to everything that goes into your body. This includes alcohol. Drinking has an effect on many substances in the body, including the chemicals that regulate blood sugar. Further, these effects are not always predictable: your blood sugar may increase or decrease, depending on how much you drink and whether you drink on an empty stomach. For this reason, a solid understanding of the link between blood sugar and drinking is important for safety if you consume alcohol.

How Alcohol Impacts the Liver When You Have Diabetes

Although many people consider drinking alcohol to be enjoyable, your liver does not have the same perspective. Under normal circumstances, your liver is responsible for creating a large amount of the sugar circulating in your bloodstream, a process called gluconeogenesis. However, the liver considers alcohol to be a toxin that needs to be removed from the body, which takes priority over other physiological concerns. As such, as soon as you start drinking, your liver begins the hard work of ridding the alcohol from your body. Overall, about 80% of the alcohol you drink is removed from your body by the liver, causing a heavy burden on this organ. This causes a shift in some of the chemicals in your liver, including NAD and NADH, forms of nicotinamide adenine dinucleotide. This change in NAD and NADH prevents your liver from making blood sugar as easily as it normally does, leading to an extra risk of low blood sugar, or hypoglycemia.

Alcohol also stops your liver from effectively storing extra sugar as glycogen for later use. Although this does not cause an immediate drop in your blood sugar, it can cause low blood sugar later on, especially in people who:

-Are malnourished

-Drink excessively

-Consume a low carbohydrate diet


-Drink without consuming food

When someone stops eating, their liver breaks down glycogen into sugar, a process called glycogenolysis. However, after one or two days of fasting, the body’s glycogen becomes depleted. If a person is fasting but not drinking, their livers can compensate for this by creating new sugar through the process of gluconeogenesis. However, alcohol’s prevention of gluconeogenesis can lead to critically low blood sugar.

Drinking on a Full Stomach

Although it is important to be vigilant about your blood sugar levels when you have diabetes, if you are having one or two drinks on a single occasion, there might not be a big impact on your blood sugar, even if you have Type 1 diabetes. This is especially true if you are drinking with a meal.

That said, if you consume regular meals and consume a high quantity of alcohol, you can end up with high blood sugar. One study showed that people with diabetes who drank between three and four alcoholic beverages daily had increased fasting blood sugar levels. For this reason, experts recommend avoiding alcoholic drinks that are especially high-calorie, like liqueurs and mixed drinks like margaritas and piña coladas.

Drinking on an Empty Stomach

Consuming alcohol on an empty stomach or several hours after eating can cause low blood sugar. This is, in part, due to the chemical changes in your liver that stop it from creating sugar while it is otherwise occupied with ridding your body of alcohol. Dangerously low blood sugar levels can be a chronic problem for those who regularly consume alcohol without eating.For this reason, it is best to avoid drinking on an empty stomach.

Alcohol and Diabetes Medications

It is important to use your diabetes medications carefully when drinking. Some diabetes medications carry a risk of low blood sugar, which may be even more pronounced if your blood sugar levels drop from drinking. If you take a medication which can cause low blood sugar, experts recommend checking your blood sugar more frequently for up to 24 hours after your last drink. Medications that can increase the risk of hypoglycemia include:

-All insulin products

-Sulfonylureas like glipizide (Glucotrol), glyburide (Glynase), and glimepiride (Amaryl)

-SGLT2 inhibitors like dapagliflozin (Farxiga), empagliflozin (Jardiance), canagliflozin (Invokana), and ertugliflozin (Steglatro)

Complications from Drinking in Diabetes

When you have diabetes, it is important to be careful about drinking, especially heavy amounts over the long term. Diabetes experts generally follow US dietary guidelines when it comes to a safe amount of alcohol, with a recommended limit of 1 drink per day for women and 2 drinks per day for men with diabetes. Heavy drinking in people with diabetes, especially Type 1 Diabetes, has been linked to:

-Insulin resistance, in which your body cannot use insulin as effectively

-Problems keeping blood sugar under control

-Elevated levels of hemoglobin A1c, a lab value that tells doctors how well your diabetes is controlled

-Increased rates of diabetic ketoacidosis, also known as DKA, a potentially fatal medical emergency

When you have diabetes, it is especially important to be careful about drinking on hot days. People with diabetes get dehydrated more easily than people without the disease. This occurs because high blood sugar causes urination, leading to dehydration. Because alcohol acts as a diuretic, increasing urination and causing dehydration, drinking alcohol when you are dehydrated can be dangerous. Because hot weather is also dehydrating, it is possible to become easily dehydrated if you drink alcohol outside on a hot day. Tips for drinking when it’s hot are:

-Make sure to drink a lot of water, even if you don’t think you are thirsty

-Check your blood sugar often. This includes before, during and after you drink.

In many cases, having diabetes does not mean that you have to live an alcohol-free life. However, it is important to take precautions, including making sure not to drink on an empty stomach, to stay hydrated, and check your blood sugar more frequently if directed by your doctor.


Centers for Disease Control and Prevention. “Managing Diabetes in the Heat.” July 12, 2018. Accessed November 25, 2020

Emanuele, Nicholas V; Swade, Terrence F; Emanuele, Mary A. “Consequences of Alcohol Use in Diabetics.” Alcohol Health & Research World, 1998. Accessed November 25, 2020.

White, Nicole D. “Alcohol Use in Young Adults With Type 1 Diabetes Mellitus.” American Journal of Lifestyle Medicine, November-December 2017. Accessed November 25, 2020.

Wannamethee, Sasiwarang G; et al. “Alcohol Consumption and the Incidence of Type II Diabetes.” Journal of Epidemiology and Community Health, 2002. Accessed November 25, 2020.

U.S. National Library of Medicine. “Drug-induced low blood sugar.” October 12, 2018. Accessed November 25, 2020.

American Diabetes Association. “Alcohol.” N.d. Accessed November 25, 2020.

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