Alcohol consumption literally “stirs up a cocktail” of multiple metabolic processes, and scientists have yet to connect all the dots between the numerous mechanisms and endpoints. While one alcoholic drink per day may improve your blood glucose management and insulin sensitivity, particularly if consumed just before or during a meal, if you have diabetes and/or you’ve been fasting or following a low-carb diet, alcohol’s effect on your liver could cause your blood glucose level to fall precipitously (hypoglycemia), which can be dangerous. Anything higher than “moderate consumption” of alcohol can set off an array of medical complications, including disturbances in fat metabolism, nerve damage and eye disease.

For those of us who do not have diabetes, it’s pretty to think that 1-2 drinks per day might confer certain health benefits, including mild protection against cardiometabolic disorders; but new research has cast doubt on that dream. Furthermore, the idea of holding your alcohol consumption to one drink (for women) or two (for men) per day is a slippery slope that many cannot manage, and higher consumption is associated with a world of health problems including obesity, hypertension, coronary artery disease, stroke, pancreatitis, liver and kidney diseases, type 2 diabetes (T2D), insomnia, and mental illnesses (anxiety, depression, alcohol addiction) — not to mention the higher rates of automobile accidents, domestic violence and death relating to excessive alcohol consumption.

Alcohol and blood sugar: what effect does it have?

Depending on your health status, your diet and the amount of alcohol you consume (among many other possible variables), alcohol may cause your blood sugar (blood glucose) level to fall or rise. 

The biochemistry

Under normal conditions, the liver makes glucose from chemical building blocks like lactate, alanine, and glycerol in a process called gluconeogenesis — but alcohol consumption is known to directly inhibit that process, which can lead to lower circulating glucose levels. To counter this decrease, alcohol stimulates the breakdown and release of stored glucose (from glycogen in the liver and muscles) in a process called glycogenolysis. Both of these processes are intended to release glucose into the blood to provide energy to our brain and muscles and prevent hypoglycemia, a sometimes-dangerous state when glucose levels are too low.

If you’re healthy… 

For those of us who are relatively healthy and consume a balanced, healthy diet, moderate alcohol consumption does not appear to affect blood glucose levels dramatically. How do we define “moderate”? Clinicians typically say that one drink for women and two drinks per day for men is moderate, assuming the drink size is 5 ounces of wine, a 12-ounce beer or 1.5 ounces of an 80-proof spirit. 

At that consumption level, research has demonstrated that your A1c level, the gold standard test of blood glucose levels, actually may be lower than at times you aren’t drinking. However, a 2019 analysis cast doubt on the “usefulness” of the A1c test post-alcohol consumption; when they discovered that white college-educated females had “average” A1c levels (of around 5%) even after drinking moderate-to-high amounts of alcohol, researchers realized that in all likelihood “the A1c is highly influenced by dietary patterns, which was not included in [their] current model.” In other words, it might have been the healthier diet of the white educated women that moderated their A1c levels, rather than the alcohol.

Nevertheless, the lower A1c effect has led researchers to study whether alcohol consumption might lower the longer-term risk of developing type 2 diabetes (T2D). And, indeed, a 2015 meta-analysis found that moderate alcohol consumption appeared to offer some protection against T2D in women and Asian populations, while heavy consumption raised the risk in almost all groups. Other studies have shown that only red wine has antihyperglycemic effects, scientists hypothesizing that the polyphenols (e.g., resveratrol) in red wine may exert protective effects in relation to T2D. More recently, a very large 2022 epidemiological analysis of health data for nearly 312,400 current drinkers found that consuming alcohol, most notably (but not only) wine, but only with meals, was associated with a lower risk of developing T2D. 

However, other recent research studies have cast doubt on the hoped-for beneficial effects of alcohol consumption on T2D risk in otherwise healthy individuals. A large 2019 prospective community-based study that looked at alcohol consumption and how it interacts with genetic variables concluded that alcohol plays an important role in the development of T2D by increasing insulin resistance. T2D risk was approximately 1.5-fold higher for alcohol drinkers than for nondrinkers. Alcohol consumption also interacted with T2D genetic risk. 

The debate ceases when heavier-than-moderate drinkers are studied. Clearly, clinical evidence points to the fact that excessive alcohol consumption can lead to alcoholic liver disease (ALD) and chronic inflammation of the pancreas (pancreatitis), both of which can impair the ability to secrete insulin, thereby causing glycemic dysregulation and potentially leading to diabetes.  

Alcohol and diabetes: what effect does it have?

Alcohol consumption is a recognized risk factor for hypoglycemia (low blood sugar) in individuals with type 1 diabetes. Particularly at times when you’re not eating, such as between meals or when you’re sleeping, the liver is making glucose and sending it into the bloodstream, preventing or mitigating a low blood sugar reaction. But when you drink alcohol, this process can be disrupted, causing blood glucose to fall too low, which can be very dangerous. In extreme cases, a hypoglycemic state can lead to seizures, coma, or death. Therefore, medical providers typically recommend that those with diabetes eat some carbohydrate foods when they consume even a moderate amount of alcohol, and to have a small snack before bedtime.

Ironically, some of the symptoms of low blood sugar levels resemble being tipsy or drunk, including slurred speech, confusion, dizziness and sleepiness — which means that someone with you when you’re experiencing an episode of low blood sugar may not realize that what is happening to you could be hypoglycemia. 

In the case of those individuals with T2D, the effects of alcohol are more controversial. A 2019 meta-analysis showed that moderate alcohol consumption could have a positive effect on blood glucose and fat metabolism in T2D patients. Other studies, however, are conflicting ― some found that alcoholic beverages decreased glucose utilization, others found that such beverages increased insulin sensitivity. To date, major medical organizations continue to recommend that diabetic individuals avoid or minimize alcohol consumption given the potential for so many other medical complications.

As stated previously, A1c testing may distort the “benefit” of modest daily alcohol consumption: alcohol may reduce the diagnostic efficiency of the test, which may lead to misleading clinical conclusions (based on a falsely lowered A1c), which in turn may lead to undertreatment. 

Beyond blood sugar: The bigger cardiometabolic picture

Glycemic control, or blood glucose management, is a vitally important marker of metabolic health — but it’s not the only one. Alcohol affects your body in so many other ways that, beyond the blood glucose effects, can alter your metabolic health status. In a number of these other respects, the benefits of not drinking likely outweigh possible benefits of alcohol consumption. For example, decreasing alcohol consumption has actually been shown to improve weight loss among individuals with T2D, and weight management is a key to better outcomes with this disorder. And if you don’t have diabetes, a 2016 study found that simply reducing weight by 5-10% could significantly lower all metabolic factors and reduce risk for diabetes and heart disease. Reduced alcohol consumption can also help you sleep better, and improved sleep quality/quantity can benefit weight management. (Learn more: Why Do I Keep Waking Up at 3 a.m.?)

But what about alcohol and heart health? Isn’t it true that drinking a glass of wine a day is healthy? Well, the jury is still out even on that one. While a 2007 study concluded that patients with hypertension benefit from moderate alcohol consumption, it did find that alcohol increases blood pressure in a dose-dependent fashion at intakes above 2 drinks daily. Worse, binge drinking increases risk of myocardial infarction (MI), all-cause mortality, and other adverse outcomes — even among otherwise light drinkers. 

As damning, a very large (371,463 participants) cohort study published just this year in JAMA Open Network has challenged the theory that light alcohol consumption benefits heart health, suggesting instead it may be attributed to other lifestyle factors common among light to moderate drinkers.

Furthermore, drinking in excess of a moderate level clearly increases the risk of high blood pressure, and if you already have high blood pressure and are on medication to treat it, alcohol blunts the benefits of those medications. 

Key takeaways

Moderate (one drink for women, two for men) daily consumption of alcohol does not seem to greatly impact the glucose levels of healthy individuals. While a body of clinical research has pointed to metabolic (e.g., reduced risk of type 2 diabetes) and cardiovascular benefits of such moderate alcohol consumption, recent research has cast doubt on those potential benefits. Clearly, alcohol use is not particularly easy to moderate, and consumption any greater than moderate can lead to a cascade of negative metabolic effects and increase the risk of developing diabetes and numerous other serious medical conditions. For those with diabetes, heavy drinking can cause dangerously low blood glucose (hypoglycemia), plus bring about higher rates of insulin resistance, impaired glucose regulation in the long term and higher blood pressure.