Alcohol and the risk of hypoglycemia over the next 24 hours

The liver is forced to deal with alcohol as a priority. While it breaks alcohol down, the production of new glucose from proteins and other substances, called gluconeogenesis, falls by almost half [1] [2] [3]. Between meals and at night, the liver releases part of this glucose into the blood and thus prevents hypoglycemia. If the liver releases less glucose, the same dose of basal insulin lowers blood glucose more than on days without alcohol.

Alcohol also weakens the hormonal defense against hypoglycemia. After a few drinks, growth hormone and cortisol respond more weakly to falling blood glucose [4] [5]. You also feel the first signs of hypoglycemia less easily [2]. The sugar in a drink may raise blood glucose at first, and the fall in blood glucose may then appear only a few hours later [1].

Up to 24 hours after the last drink [1]. Hypoglycemia occurs most often 6–12 hours after drinking alcohol, that is, in the second half of the night or in the morning [6]. After 2–3 glasses of wine, hypoglycemia may appear only the next day, after breakfast, around 10–11 a.m., as the figure below shows [7].

Next-day hypoglycemia is associated with lower growth hormone secretion during the night [7]. Normally, this hormone helps maintain blood glucose in the morning hours. That is why the risk of hypoglycemia does not end at bedtime. That night, check that your sensor alarms are on, and the next day test your blood glucose on waking and after breakfast [2] [7].

There is no amount without a risk of hypoglycemia. The risk rises with every drink, because liver glucose production, judgment and the perception of hypoglycemia signs all decrease at the same time [1]. Severe hypoglycemia after drinking alcohol is more frequent in patients who usually have at least two drinks on a single occasion [8]. For health in general there is no safe level of drinking either, and if you do not drink, there is no reason to start [9].

If you still decide to drink, the limits for adults are at most one drink a day for women and at most two for men [9]. One drink means about 150 ml of wine, 330 ml of beer or 40 ml of spirits, that is, 12–14 g of alcohol. Choose small amounts, drink alcohol only with food and keep your glucometer at hand [9] [10].

Yes. On an empty stomach, the glycogen stores in the liver are smaller, and alcohol reduces the production of new glucose from other substances [2]. The risk is even higher after physical exercise, such as dancing, or after a skipped meal, when the glycogen stores are smaller [1] [2].

Alcohol is consumed only together with food [10]. Food provides carbohydrates during the hours when the liver produces less glucose, and it slows the absorption of alcohol. Drunk with a meal, alcohol usually does not lower blood glucose in the following hours [11]. Drinks taken in the evening, after dinner, can however lead to hypoglycemia the next morning [7].

Beer does, dry wine hardly at all. A regular beer has about 3–4 g of carbohydrates per 100 ml, so a 330 ml bottle provides 10–13 g of carbohydrates. Alcohol-free beer may contain even more carbohydrates, about 5–6 g per 100 ml [12]. Dry wine has less than 2 g of sugar per glass, and spirits contain no carbohydrates. Sweet wine, cider, liqueurs and ready-made sweetened drinks provide much more, sometimes 20–30 g of carbohydrates per serving.

The sugar in a drink raises blood glucose at first, then alcohol lowers it a few hours later [1]. If you take insulin for all the carbohydrates in beer, the effect of that insulin dose adds to the later fall in blood glucose. You agree with your doctor in advance whether you cover the carbohydrates in alcoholic drinks with insulin, and to what extent. The carbohydrates in alcohol-free beer are counted like those in any other drink.

The plan is set in advance, with your doctor, not at the table. The most important rule concerns corrections. After drinking alcohol, a high blood glucose at bedtime is not corrected as usual, because the fall in blood glucose comes anyway a few hours later [1]. The situations in which you avoid corrections are described on the page about the insulin sensitivity factor.

Many patients need a lower insulin dose at dinner or less basal insulin for that night. Evidence for any specific reduction is scarce, so you set its size in advance with your doctor, based on your sensor graphs [10]. Do not skip your basal insulin, however, because alcohol can also increase the risk of diabetic ketoacidosis [1].

A snack with carbohydrates that are absorbed slowly, such as a slice of bread, a yogurt or a piece of fruit [2]. Its role is to cover the hours when the liver produces less glucose. You do not need a full meal, and the snack is taken without an insulin bolus, unless the plan agreed with your doctor says otherwise. Concentrated sweets raise blood glucose too quickly, and their effect lasts too briefly.

Test your blood glucose before bed. A blood glucose below 100 mg/dL (5.6 mmol/L) at bedtime can double the risk of nocturnal hypoglycemia [2]. Keep your sensor alarms on all night, because a reliable alarm helps you recover faster from an episode of nocturnal hypoglycemia [13]. If your sensor allows data sharing, someone close to you can also receive the alarms [1]. If you live alone, tell someone that you have been drinking and ask them to give you a check-in call the next morning.

Yes, and this similarity can delay the treatment of hypoglycemia. Slurred speech, unsteady walking, drowsiness and confusion occur both in hypoglycemia and after drinking alcohol [6]. People around you may put the signs down to the drink, and hypoglycemia may thus go untreated [1]. After a moderate amount of alcohol, hypoglycemia is recognized much less often, even though sweating is heavy [14].

Only a blood glucose test reliably tells hypoglycemia apart from the effect of alcohol. After drinking alcohol, the sensor may be somewhat less accurate, so use your glucometer to confirm a low value or one that does not match how you feel [15]. Wear a medical ID bracelet or card showing that you have type 1 diabetes and use insulin [16]. If you cannot swallow, do not respond or have seizures, the people around you give you nothing by mouth, give you glucagon and call emergency services immediately [17].

At least one person you spend the evening with. They need to know that you have diabetes, what hypoglycemia looks like in you and where you keep your glucose and glucagon. Tell them in advance, before the first drink, because during a hypoglycemic episode your judgment is impaired and you may deny having a problem [2]. Agree at the same time on how you will get home, because after drinking alcohol you cannot drive, not even below the legal limit [18].

After drinking alcohol, glucagon still raises blood glucose, but its effect may be smaller [19]. In severe hypoglycemia, the person helping you gives you glucagon and calls emergency services at the same time [17]. The steps for the people around you are on the page about severe hypoglycemia.

Yes. The sugar in juice or syrup raises blood glucose in the first hour, and the high blood glucose on the glucometer gives the impression that you are safe [1]. The alcohol in the same glass, however, acts for hours, after the sugar has been used up. The result is high blood glucose in the evening and low blood glucose at night or in the morning [6].

The second trap is the correction. A correction insulin dose given for the rise in blood glucose after a cocktail adds its effect to the later fall in blood glucose. If you choose mixed drinks, ask for a mixer without sugary ingredients and do not make corrections as usual that evening. A drink with sweetener prevents the early rise in blood glucose, but not the fall in blood glucose that comes later after drinking alcohol.