How Does Alcohol Affect Blood Sugar Levels?
Written by: Liad Stearns, MSc
Reviewed by: Emily J., MSc RD
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Learn how alcohol impacts blood glucose immediately after consumption, the effect of alcohol on metabolic health the next day, and how chronic alcohol use may influence long-term metabolic health.
If you monitor your blood glucose, you may notice that alcohol can have variable effects. This is likely because there are many factors that play a role in determining your glycemic response to alcohol. These factors include the type of alcohol consumed, if it was mixed or contains any added sugars, and if you’ve eaten that day. It’s also important to keep in mind that one night of moderate drinking is not comparable to chronic heavy use.
To best explain the immediate impact of alcohol on glucose, it’s important to understand the role of the liver in glucose metabolism. The liver is the main organ controlling blood glucose homeostasis (balance) and acts as a reservoir for glucose in the body. It balances the processes of removing glucose from the bloodstream and storing it as glycogen by synthesizing and releasing new glucose for the body to use as fuel. This intricate relationship is essential for keeping blood glucose within a narrow physiologic range.
When alcohol is consumed, it is metabolized primarily in the liver. As alcohol is being broken down it inhibits the liver’s natural process of gluconeogenesis, the metabolic pathway that creates glucose. Less glucose being produced by the liver means lower blood glucose levels. However, in opposition, alcohol has been shown to increase glycogenolysis, the breakdown of stored glycogen into glucose. The result of these opposing actions is a relatively balanced glucose response. Different bodies will react differently, so this balance may not be perfect depending on the person. Monitoring your blood glucose is a good way to see what’s true for you. Clinical studies have demonstrated that acute alcohol administration can lead to a slight reduction or no change in whole-body glucose levels.
Some research suggests that consuming a moderate amount of alcohol prior to a carb-heavy meal can lead to a blunted glucose spike in comparison to the same meal eaten without alcohol. One study in 63 healthy postmenopausal women found that consumption of 30g of alcohol per day (equivalent to 2 drinks) lowered postprandial glycemia by 16-37%. This is likely due to an acute increase in insulin sensitivity, which allows for glucose to be easily transported into cells and may lower blood glucose levels.
All of this will depend on the type of alcohol consumed, and the other ingredients present, like a mixer in a cocktail.
The impact of alcohol on blood glucose differs if the body is in a fasted or ketogenic state. In a fasted state, the body contains less stored glucose in the liver and muscles in the form of glycogen. When the liver recognizes that glucose levels are low, it stimulates gluconeogenesis to produce new glucose — however, alcohol inhibits this process. This can result in lower-than-normal glucose levels and, in extreme cases, a hypoglycemic event.
It’s commonly understood that a night of drinking can negatively impact your energy levels and mood the following day. This may even be the case with moderate alcohol consumption. Research suggests that there’s a strong association between alcohol consumption and sleep disruption through multiple mechanisms. Alcohol has been linked to difficulty falling asleep, circadian rhythm abnormalities, and insufficient sleep duration. One study found that a moderate dose of alcohol in the evening suppressed melatonin production by 15% and 19% when measured at 140 and 190 minutes after alcohol consumption, respectively.
Through its effect on sleep, alcohol consumption has an impact on glucose sensitivity. While many studies in diabetic populations have demonstrated the association between poor sleep and dysregulated blood sugar[6,7], an interesting study from 2021 investigated the impact of insufficient sleep on glycemic control in a non-diabetic population. Researchers examined how the body responded to different sleep inputs, including the number of hours of sleep, quality of sleep, and how “typical” the subjects’ sleep was in comparison to their normal. Glucose was measured in response to standardized test meals the following morning. Researchers concluded that poor sleep efficiency and later bedtime routines are associated with a greater glycemic response to breakfast the following morning, and a person’s deviation from their usual sleep pattern is associated with worse post-meal glycemic control.
So what can you take away from this? Alcohol consumption negatively impacts sleep quality, which can lead to increased glucose sensitivity and a higher glycemic response to the same meal the next morning. If you do choose to consume alcohol, opt for a savory, protein-rich breakfast over pancakes the next morning.
Chronic heavy alcohol use occurs in as many as 5% of US adults and puts the user at a higher risk for developing insulin resistance and type 2 diabetes. Excessive alcohol consumption can also lead to tissue damage in the liver, known as alcoholic liver disease (ALD). While the relationship between alcohol consumption and the development of type 2 diabetes is not entirely understood, research suggests that chronic alcohol consumption leads to the dysfunction and death of pancreatic beta cells. These cells typically function to store, synthesize, and release insulin and are essential in maintaining whole-body circulating glucose concentrations within a healthy range. When pancreatic beta cells are impaired, their ability to secrete insulin in response to a rise in blood glucose is reduced[11,12], resulting in higher-than-normal glucose levels in the bloodstream. Additionally, dysfunction in these cells has been shown to decrease the functionality of insulin receptor signaling, reduce the liver’s ability to store glucose as glycogen, and lower whole-liver glycogen content. These factors are a direct indication of Type 2 diabetes and glycemic dysregulation.
It’s important to keep in mind that while you may experience a lowered post-meal glucose response from alcohol consumption, it’s useful to consider other metrics such as the impact of alcohol on sleep quality. Alcohol negatively impacts sleep quality, which in turn leads to dysregulated glycemic control. Additionally, being in a ketogenic or fasted state may lead to particularly dangerous health outcomes even when consuming alcohol in moderation.
As mentioned, alcohol can have a multi-layered effect on metabolism. While minimizing alcohol consumption is encouraged, moderate alcohol intake (0.5-1 drink per day in women, 1-2 drinks per day in men) has been shown to have a slight impact in reducing the risk of Type 2 diabetes and increasing insulin sensitivity. In contrast, excessive alcohol intake or binge drinking can lead to an increased risk for a wide array of poor health outcomes. A lot of existing research demonstrates this as a J-shaped association between alcohol intake and adverse health outcomes.
If you want to indulge in a drink, don’t sweat it! Just be conscious of the type of alcohol and how it may be affecting your sleep. Also be mindful that we tend to overeat when we drink, so plan your meal accordingly.