Alcohol can raise blood sugar if a drink has carbs, then cause a low up to 24 hours later, mainly in people who use insulin or sulfonylureas. Here is why, how many carbs common drinks contain, and what Diabetes Canada, the ADA and Canada’s alcohol guidance say.
Alcohol can raise blood sugar when a drink contains carbohydrate, and it can cause a low up to 24 hours later, mainly in people who use insulin or insulin secretagogues, medicines such as sulfonylureas that make the pancreas release more insulin 1, 3. The delayed low happens because the liver makes less new glucose while it is breaking down alcohol 4, 11. Diabetes Canada warns that for people with type 1 diabetes, and people with type 2 diabetes who use these medicines, “a delayed low blood sugar can occur anytime up to 24 hours after drinking alcohol” 1.
This article explains why, what common drinks contain, how lows are recognized and treated, and what guidelines and large studies say. It is not a reason to start drinking: the American Diabetes Association (ADA) advises people who don’t drink not to start 2.
Alcohol can do both: the carbohydrate in a drink can raise glucose soon after, while the alcohol itself tends to lower it, sometimes hours later. Mayo Clinic notes that alcohol “can lead to low blood sugar shortly after you drink it and for hours afterward” 11. The ADA’s Standards of Care list the risks as hypoglycemia (a low) or delayed hypoglycemia, “particularly for those using insulin or insulin secretagogue therapies,” weight gain, and hyperglycemia (high glucose) with excessive drinking 2. The ADA’s patient information adds that more than three drinks a day “can lead to higher blood glucose and A1C” 3 (see A1c and average glucose).
Alcohol can cause a delayed low because the liver makes less new glucose while it is breaking down alcohol. Between meals and overnight, the liver keeps glucose up by breaking down glycogen, a stored form of glucose, and by making new glucose, a process called gluconeogenesis 4. A 1998 review in a journal of the US National Institute on Alcohol Abuse and Alcoholism (NIAAA) explains that alcohol metabolism in the liver “actually shuts down the process of gluconeogenesis” 4. Glycogen is generally used up after 1 or 2 days without food, so drinking without eating removes both defences 4. Even on an ordinary evening, Mayo Clinic says, “if your liver is processing alcohol, it may not give your blood sugar the needed boost” 11.
In a 2001 study in Diabetes Care, six men with type 1 diabetes were each studied twice, on set insulin doses that included an overnight infusion. Starting at 9 p.m., they drank either dry white wine, at 0.75 g of alcohol per kilogram of body weight, or mineral water over 90 minutes 5. Overnight glucose did not differ between the two nights, and alcohol was undetectable in their blood by 8 a.m. But after breakfast, glucose peaked at an average of 8.9 mmol/L (160 mg/dL) after wine, compared with 15 mmol/L (270 mg/dL) after water. From 10 a.m., five of the six men needed treatment for lows of 1.9 to 2.9 mmol/L (34 to 52 mg/dL); none had a low after water 5. After wine, they also released less growth hormone between midnight and 4 a.m. 5, a hormone that pushes glucose up toward morning (see the dawn phenomenon).
The study was small, and its participants stayed in a research unit with reduced mealtime insulin and overnight insulin given into a vein 12. A 2005 report that pointed this out also noted that in people treated with insulin, alcohol has been implicated in up to one-fifth of hospital visits for hypoglycemia 12.
The ADA’s 2026 Standards of Care recommend counselling people about delayed hypoglycemia and “the importance of monitoring glucose after drinking alcohol to reduce hypoglycemia risk, especially when using insulin or insulin secretagogues” 2. Diabetes Canada says drinking with, or 2 to 3 hours after, an evening meal may cause a low the next morning after breakfast, and suggests checking blood sugar before bed 1. Mayo Clinic adds that “drinking alcohol on an empty stomach can cause hypoglycemia” 7.
Activity lowers glucose too. An ADA position statement reports that lows after exercise typically happen within 6 to 15 hours, and that the risk can extend to 48 hours 13. The ADA warns that after drinking, hypoglycemia “can strike hours after your last drink, especially if you’ve been exercising” 3. Diabetes Canada’s alcohol handout advises extra carbohydrate-rich food for people who are dancing, playing sports or doing other physical activity 1. Its guideline adds that the body’s adrenaline-driven warning response to a low is reduced during sleep, and after exercise or alcohol 6, so drinking, dancing and then sleeping combine all three. More in exercise and glucose.
In plain terms: While your liver is busy breaking down alcohol, it makes less new glucose. If you use insulin or a medicine such as a sulfonylurea, glucose can then fall too low, sometimes the next morning after breakfast, long after you feel sober.
Regular beer, coolers, liqueurs, dessert wines and sugary mixers carry enough carbohydrate to raise glucose, while ordinary wine has little and spirits only a trace 1, 3. Diabetes Canada gives these approximate amounts 1.
| Drink | Serving | Carbohydrate |
|---|---|---|
| Regular beer | 341 mL (12 oz) | 12 g |
| Light beer | 341 mL (12 oz) | 6 g |
| Low-carb beer | 341 mL (12 oz) | 3 g |
| Non-alcoholic beer | 355 mL (about 12 oz) | 9 to 17 g |
| Regular wine | 142 mL (5 oz) | 2 to 4 g |
| Dessert wine | 142 mL (5 oz) | 18 to 21 g |
| Liqueurs and cordials | 43 mL (1.5 oz) | 10 to 25 g |
| Regular cooler | 355 mL (12 oz) | 21 to 38 g |
| Regular pop | 250 mL (8 oz) | 28 g |
| Tonic water | 250 mL (8 oz) | 23 g |
| Orange juice | 250 mL (8 oz) | 27 g |
| Sugar-free pop | 250 mL (8 oz) | 0 g |
In a mixed drink, the mixer often carries the carbohydrate. Mayo Clinic notes that “sugar-free mixers won’t raise your blood sugar” and that light beer and dry wines have fewer carbohydrates than other alcoholic drinks 11. Diabetes Canada’s table does not list cider, and none of this article’s sources gives a figure for it, so the maker’s nutrition information is the place to check.
Sugary drinks won’t prevent a later low: the ADA notes that liquid sugars are absorbed quickly, while food is digested gradually and “provides better protection against lows” 3. Diabetes Canada’s handout also says: “If you are carbohydrate counting, do not take insulin for the carbohydrate content of alcoholic drinks” 1. Your care team can explain how that applies to you; see also how to count carbs.
A low can be mistaken for being drunk because many of its signs are the same. The ADA explains: “Because many of the symptoms of hypoglycemia—such as slurred speech, drowsiness, confusion, or difficulty walking—are also symptoms of being drunk, it can be difficult to tell the two apart” 3. Alcohol can also blunt the early warnings. The NIAAA review links alcohol-related “hypoglycemic unawareness,” not noticing the usual warning signs of a low, to the impaired thinking that comes with blood alcohol levels of 0.08 to 0.1 percent 4. Diabetes Canada asks that someone with you knows your signs of a low 1.
Identification helps others act. Diabetes Canada’s guideline and its alcohol handout both say to wear diabetes identification, such as a MedicAlert® bracelet 1, 6. Mayo Clinic advises carrying “some form of diabetes identification so that in an emergency others can see that you have diabetes” 7, and Cleveland Clinic advises a medical alert necklace or bracelet that says you have diabetes 14.
For a mild to moderate low, Diabetes Canada’s guideline recommends 15 g of carbohydrate by mouth, a recheck after 15 minutes, and another 15 g if glucose is still low 6. The ADA also advises 15 g and a recheck after 15 minutes 15. Our article on low blood sugar explains how lows are defined and graded.
Alcohol complicates emergency treatment with glucagon, a medicine that raises glucose in a severe low. Diabetes Canada’s guideline says its effectiveness “is reduced in individuals who have consumed more than 2 standard alcoholic drinks in the previous few hours” 6. Its handout warns more bluntly that glucagon “will not work while alcohol is in the body” 1.
When to get urgent help: the ADA says “emergency medical services should be called for people who are unalert or unable to administer carbohydrates” 15. Mayo Clinic advises calling 911 or local emergency services right away if the person is not conscious, or if you can’t find their glucagon or don’t know how to use it 7. Diabetes Canada’s handout asks that someone with you knows “to call an ambulance if you pass out” 1.
All three set limits for people who drink, and Canada’s 2023 guidance is the strictest 1, 2, 8.
The ADA’s 2026 Standards of Care recommend advising adults with diabetes who drink “to not exceed the recommended daily limits”: 2 drinks a day or fewer for men and 1 or fewer for women, where a drink is a 12-oz beer, a 5-oz glass of wine or 1.5 oz of distilled spirits 2. People who don’t drink should be advised “to not start drinking alcohol, even in moderation.” The section also notes the World Health Organization’s position that “there is no safe amount of alcohol intake” 2.
Diabetes Canada’s alcohol handout, which reflects its 2018 guidelines, limits moderate drinking to 2 standard drinks a day or fewer than 10 a week for women, and 3 a day or fewer than 15 a week for men, with lower daily limits for people with high blood pressure 1. A standard drink is 341 mL of 5% beer, 142 mL of 12% wine or 43 mL of 40% spirits 1. These weekly limits match Canada’s 2011 low-risk drinking guidelines 8.
Canada’s Guidance on Alcohol and Health, published in 2023 by the Canadian Centre on Substance Use and Addiction, describes a continuum of risk and advises people who drink that “less is best.” It defines “moderate risk” as 3 to 6 drinks a week for men and women, counts 7 or more a week as risky for long-term harm, and sets 2 drinks a day as the upper limit for short-term harm 8. Diabetes Canada’s 2018 handout predates it 1.
Yes: heavy drinking can cause ketoacidosis, excessive alcohol is a risk factor for ketoacidosis with SGLT2 inhibitors, and metformin information warns about alcohol 4, 15, 16. Your prescriber can explain what applies to you; don’t change a medicine on your own.
Ketones are acids the body makes when it burns fat for fuel, and a dangerous build-up is called ketoacidosis. The NIAAA review notes that heavy drinking, about 200 g of alcohol a day or roughly 16 standard drinks, “can cause ketoacidosis in both diabetics and nondiabetics,” often in people who have been drinking and not eating for days 4.
SGLT2 inhibitors are glucose-lowering tablets whose names end in “-gliflozin.” In type 2 diabetes they rarely lead to diabetic ketoacidosis (DKA), at 0.6 to 4.9 events per 1,000 patient-years. The ADA lists “excessive alcohol intake” among the risk factors, along with very-low-carbohydrate diets, prolonged fasting, dehydration and autoimmunity 15. It also flags euglycemic DKA, ketoacidosis without very high glucose 17. Our article on high blood sugar describes the warning signs of DKA.
Mayo Clinic’s metformin information says “drinking alcohol may cause severe low blood sugar” and lists alcohol use disorder among conditions in which metformin is used with caution 16. The 1998 NIAAA review said people who misuse alcohol, and so risk liver damage, must not take metformin 4. Diabetes Canada also warns that “missed medication or insulin can lead to high blood sugar, ketones and diabetic ketoacidosis (DKA)” the day after drinking 1.
Large observational studies link light drinking with a lower risk of type 2 diabetes, but they can’t show that alcohol causes it, and in some analyses the link disappears. A 2015 meta-analysis of 38 observational studies, covering 1,902,605 people and 125,926 cases, found lower risk at every intake below 63 g of alcohol a day compared with non-drinkers, with the largest reduction, 18%, at 10 to 14 g a day 9. But the reduction appeared limited to women, and it was absent in studies that compared drinkers with people who had never drunk and in Asian populations. Most studies compared drinkers with all non-drinkers, including former drinkers, and the authors warned the benefit may have been overestimated by comparison groups “contaminated by less healthy former drinkers” 9.
A 2025 analysis of three US cohorts of nurses and health professionals, 200,969 people followed for more than three decades, excluded former regular drinkers from the non-drinker group. It found lower risk with light to moderate drinking, driven mainly by how often people drank rather than how much 10.
These studies show associations, not cause and effect: light, regular drinkers may differ from non-drinkers in many other ways. The ADA notes that the J-shaped link between alcohol and health risks “likely varies by sex, obesity status, genetics, and alcohol intake behaviors” 2. Mayo Clinic says moderate drinking was once thought to be linked with a lower risk of dying from heart disease and possibly diabetes, but “after more analysis of the research, that doesn’t seem to be the case” 18.
Diabetes Canada says a delayed low can happen anytime up to 24 hours after drinking, mainly in people who use insulin or insulin secretagogues 1. In a 2001 study, five of six men with type 1 diabetes who drank wine starting at 9 p.m. needed treatment for lows from 10 a.m. the next day 5.
Regular beer can: a 341 mL (12 oz) serving has about 12 g of carbohydrate, and light beer about 6 g 1. The alcohol can still lower glucose hours later, so an early rise can be followed by a low 11.
The ADA says people with diabetes who drink can follow the same limits as the general public, no more than 1 drink a day for women and 2 for men, and it advises people who don’t drink not to start 2. Mayo Clinic advises avoiding alcohol completely in some situations, such as pregnancy, alcohol use disorder or taking a medicine that has side effects with alcohol 18.
Mayo Clinic’s metformin information says drinking alcohol may cause severe low blood sugar and advises discussing it with your health care team 16. Your prescriber can explain what applies to you.
Carbohydrate in beer, coolers, sweet wines and sugary mixers can raise glucose 1, 3. Later, while the liver is breaking down alcohol, it makes less new glucose, so glucose can fall, sometimes the next morning 4, 5.
A night out is easier to understand afterward when the drinks sit on the same line as your glucose. In Glyve’s day view, the glucose line shows your own target range shaded, with logged meals, insulin, exercise, sleep and stress on one timeline, so you can see whether glucose rose after a sweet drink or fell the next morning. You can log a drink or a meal by typing, by voice or with a photo of a nutrition label or barcode, and each estimate is a draft you check before saving. The week view shows whether a pattern repeats after evenings when you drank. Glyve reads glucose from Apple Health, and Dexcom and FreeStyle Libre readings through your own Dexcom Share or LibreLinkUp follower account, which can arrive later than in your CGM app. Beacon lets you review and send a text to someone you trust with your latest reading, the insulin still working and, if you allow it, your location; nothing is sent on its own. Glyve is not a medical device, gives no advice and sends no glucose alarms, so it doesn’t replace your CGM’s alerts or your care team.
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Glyve keeps glucose, food, insulin, exercise, sleep and stress on one timeline.
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