Whether you enjoy an occasional glass of wine with dinner or meet friends for cocktails on weekends, understanding how alcohol affects your blood sugar is crucial—especially if you have diabetes or prediabetes. The relationship between alcohol and glucose levels is more complex than most people realize, involving intricate biochemical processes that can lead to both dangerous lows and unwanted highs. Let's explore what happens in your body when you drink and how to make safer choices.
What Happens When Alcohol Enters Your Body
The moment alcohol enters your system, your body treats it as a toxin that must be eliminated as quickly as possible. After absorption from your gut into the bloodstream, alcohol travels to your liver, where a fascinating—and critical—metabolic process begins.
Your liver uses two enzymes to break down alcohol: first, alcohol dehydrogenase converts alcohol into acetaldehyde (a toxic compound that contributes to liver damage and those unpleasant hangover symptoms), and then aldehyde dehydrogenase converts acetaldehyde into acetate. Finally, acetate breaks down into carbon dioxide and water, which your body expels through breathing and urination.
Here's the crucial part: because alcohol is toxic, your liver drops everything else it's doing to focus on metabolizing it. This includes an essential process called gluconeogenesis—the production of new glucose. When your blood sugar drops and your body needs energy, your liver normally steps in to produce glucose. But when it's busy processing alcohol, this glucose production halts, potentially leading to hypoglycemia, or dangerously low blood sugar levels.
Think of your liver as a single-tasking processor that can either make glucose or break down alcohol, but not both simultaneously. This is why drinking on an empty stomach is particularly risky—without food providing glucose through digestion, and with your liver unable to produce new glucose, your blood sugar can plummet.
The Double-Edged Sword: How Alcohol Both Lowers and Raises Blood Sugar
The impact of alcohol on your blood sugar isn't straightforward—it can push glucose levels both down and up, depending on several factors.
The Lowering Effect: As we've discussed, alcohol inhibits your liver's ability to produce glucose. This effect is most pronounced when you drink on an empty stomach or while fasting. Without food to buffer the impact, alcohol can cause significant drops in blood sugar that may persist for hours after drinking.
The Raising Effect: Many alcoholic beverages contain substantial amounts of sugar and carbohydrates that can spike your blood sugar. The type of drink matters enormously:
- Beer: Most regular beers contain 10-20 grams of carbohydrates per serving, especially darker varieties like ales, stouts, and porters. Light beers are lower in carbs and have less impact on blood sugar.
- Wine: Dry wines, including many reds and dry whites, are relatively low in sugar. However, sweet wines like Moscato, Riesling, or dessert wines can cause significant blood sugar spikes.
- Spirits: Hard liquors like vodka, whiskey, and gin contain virtually no carbohydrates. The danger comes from mixers—tonic water, juice, and soda add substantial sugar.
- Cocktails: These are the biggest culprits. A single piña colada can pack up to 70 grams of carbohydrates—that's more than 5 tablespoons of sugar, equivalent to the amount in some candy bars.
The timing matters too. You might experience an initial blood sugar spike from a sugary drink, followed hours later by a dangerous drop when the alcohol's glucose-suppressing effects kick in and the sugar has been cleared from your bloodstream.
Special Risks for People with Diabetes
If you have type 1 or type 2 diabetes, the stakes are considerably higher. Your brain depends on glucose to function properly, and when blood sugar drops too low, brain function suffers. Symptoms of hypoglycemia range from mild effects like shakiness, sweating, and irritability to severe consequences including confusion, seizures, and even coma.
Here's a particularly dangerous aspect: the symptoms of low blood sugar closely mimic intoxication. Both can cause confusion, slurred speech, unsteady movement, and drowsiness. This makes it easy for others—and even yourself—to mistake a medical emergency for simple drunkenness.
Medication Interactions You Must Know About:
Insulin: If you take insulin, drinking alcohol creates a perfect storm for hypoglycemia. Insulin moves glucose out of your bloodstream and into your cells, lowering blood sugar. When combined with alcohol's effect of stopping glucose production in the liver, blood sugar can drop to dangerous levels.
Metformin: This common diabetes medication works partly by reducing glucose production in the liver. Add alcohol, which does the same thing, and you're doubling down on suppressing glucose production. There's also a rare but serious risk: lactic acidosis, a condition where lactate builds up in the blood. Alcohol impairs your liver's ability to clear lactate, increasing this risk.
Sulfonylureas: Medications like glipizide and glyburide stimulate your pancreas to produce more insulin. When you drink, your liver can't produce glucose, but your body is producing extra insulin—a recipe for severe hypoglycemia.
If you take any of these medications, discussing alcohol consumption with your healthcare provider isn't optional—it's essential.
Strategies for Safer Drinking
If you choose to drink, these evidence-based strategies can significantly reduce your risks:
Always Eat When You Drink: Food is your best friend when consuming alcohol. It slows alcohol absorption, reducing its impact on both blood sugar and blood alcohol concentration. Food also provides glucose through digestion, compensating for your liver's inability to produce it. Choose high-fiber and high-protein options like nuts, cheese, vegetables with hummus, or a balanced meal rather than loading up on fried bar food.
Choose Lower-Sugar Options: Opt for spirits with sugar-free mixers, dry wines, or light beers. If you love cocktails, ask for versions made with fresh citrus juice and minimal added sweeteners, or try a glass of wine spritzer (wine mixed with sparkling water) to reduce both alcohol and sugar content.
Monitor Your Blood Sugar: If you have diabetes or prediabetes, check your blood sugar before drinking, while drinking, and several hours after—including before bed and upon waking. Remember that alcohol can affect blood sugar for up to 12 hours after consumption. Continuous glucose monitors (CGMs) can be particularly valuable for tracking these patterns.
Know the Limits: According to the Dietary Guidelines for Americans, moderate drinking means up to one drink per day for women and up to two for men. One standard drink equals 12 ounces of 5% beer, 5 ounces of 12% wine, or 1.5 ounces of 80-proof liquor. These aren't averages to be balanced over a week—they're daily maximums.
Never Drink Alone If You Have Diabetes: Make sure someone with you knows you have diabetes and can recognize the signs of low blood sugar. Consider wearing a medical ID bracelet.
The Long-Term Picture: Chronic Alcohol Use and Metabolic Health
Beyond immediate effects, regular heavy drinking can fundamentally alter how your body handles glucose. Research shows that chronic alcohol consumption can lead to insulin resistance, where your cells become less responsive to insulin's signals. This means your body needs more insulin to achieve the same glucose-lowering effect.
Animal studies have demonstrated that high alcohol consumption disrupts the brain's insulin signaling, damages the liver, and increases the liver's glucose production. The result? Elevated blood sugar levels and reduced insulin sensitivity that persist even after alcohol has left your system.
There's also the weight factor. Alcohol contains 7 calories per gram—nearly as much as fat (9 calories per gram) and significantly more than carbohydrates or protein (4 calories per gram). These are often called "empty calories" because they provide energy without beneficial nutrients. Regular drinking can contribute to weight gain or make weight loss more difficult, and excess weight is a major risk factor for insulin resistance, type 2 diabetes, metabolic syndrome, and heart disease.
The Bottom Line
Alcohol's relationship with blood sugar is complex and highly individual. What causes a dangerous low in one person might trigger a spike in another, depending on the type of drink, whether food is consumed, medication use, and individual metabolic factors.
For people with diabetes or prediabetes, understanding these dynamics isn't just about making informed choices—it can be life-saving. The good news is that with mindful drinking practices—consuming alcohol with food, choosing lower-sugar options, monitoring blood sugar levels, and staying within moderate limits—it's possible to reduce risks significantly.
If you have diabetes or prediabetes, consider using a continuous glucose monitor to understand exactly how different alcoholic beverages and drinking contexts affect your glucose levels. This personalized data can empower you to make choices that work for your body while still allowing you to enjoy social occasions.
Remember: there's no amount of alcohol that's beneficial for health, but if you choose to drink, doing so strategically and safely makes all the difference. When in doubt, consult your healthcare provider about how alcohol fits into your specific health situation and medication regimen.
References
American Diabetes Association. (2023). "Alcohol and Diabetes." Diabetes Care, 46(Supplement_1), S87-S92. https://doi.org/10.2337/dc23-S006
Steiner, J. L., Crowell, K. T., & Lang, C. H. (2015). "Impact of Alcohol on Glycemic Control and Insulin Action." Biomolecules, 5(4), 2223-2246. https://doi.org/10.3390/biom5042223