“A college freshman with type 1 diabetes goes to a college party with her friends on a Friday night. The next morning her dorm roommate can’t wake her up to grab an early lunch. Even shaking her fails to arouse her.”
Low blood sugar (hypoglycemia) is the first consideration anytime a person with type 1 diabetes (T1D) experiences an altered level of consciousness and/or seizures.
This story highlights a common scenario of underage alcohol consumption. Alcohol is the most widely used substance by young adults, and young adults with T1D are just as likely to drink alcohol and abuse other substances as their peers. Unfortunately, people with T1D are at high risk of developing hypoglycemia both during and after alcohol consumption.
The risk for hypoglycemia remains for up to 24 hours after the last drink. The risk of hypoglycemia is made worse in people who consume alcohol without also eating carb-containing foods. The effects of alcohol on glucose metabolism are mostly due to an impaired ability to generate new sugar (gluconeogenesis) as needed. Alcohol (ethanol) is broken down (metabolized) by liver cells (hepatocytes) into the chemicals acetaldehyde and then acetate.
The breakdown of alcohol (ethanol) occurs as a series of chemical reactions. This process subtracts (consumes) 2 NAD+ molecules and adds (generates) 2 NADH molecules, resulting in an increase in the NADH/NAD+ ratio (a chemical imbalance). NAD+ is required for the conversion of lactate to pyruvate, the first step of creating new sugar (the process known as gluconeogenesis); thus, the decreased availability of NAD+ is a limiting factor in this pathway. The result is that alcohol breakdown prevents new sugar from being created internally by the liver.
Alcohol consumption lowers the rate of new sugar formation (gluconeogenesis) by greater than 50%. There is a sugar-raising backup system called glycogenolysis which also kicks in to release previously stored sugar (not new sugar). But these stores are rapidly depleted to compensate for the lack of new sugar creation. The result is a steady lowering of the blood sugar level and an inability to raise the level through natural protective mechanisms.
Stress hormones (cortisol and epinephrine) are mostly unaffected by drinking alcohol in both non-diabetics and those with T1D. However, even modest alcohol consumption in the evening lowers nighttime growth hormone release in those with T1D and this may play a supporting role in the low blood sugar that results the next morning.
Low blood sugar when drinking alcohol is magnified in several ways. First, there may be delayed recognition of low blood sugar while drinking by both the person with T1D and their friends and bystanders. Symptoms of hypoglycemia such as dizziness, disorientation, and sleepiness are often like those of alcohol intoxication and may be easily dismissed. Even moderate alcohol consumption has been found to decrease hypoglycemia awareness despite common signs like sweating and a rapid pulse.
Thus, persons with T1D may be unaware of the hypoglycemia and/or unable to seek help or treatment. Also, the disinhibiting properties of alcohol may also cause the person to forget to check blood sugars, eat properly, or take their basal insulin properly at bedtime. The vomiting and loss of appetite that can result from consuming too much alcohol may also raise the risk for low blood sugar and hamper attempts to treat the low blood sugar with carbs.
Children and adolescents with T1D are more susceptible to the dangers of alcohol. About 3 in 10 youth with T1D report consuming alcohol. The typically age of the first drink is 15 years. Binge drinking is reported by 10% of children/teens with diabetes. Sadly, only half of teens with T1D report knowing any of the effects of alcohol on their diabetes control. It’s these unaware T1D teens who are at the greatest risk for drinking and/or binge drinking.
Kids of any age should be reminded that alcohol consumption is illegal, but if drinking does occur, it’s important to consume a carb-containing meal or snack beforehand and regularly check blood sugars while drinking and up to 24 hours afterwards. A trusted friend should be identified, taught and tasked on what to do if low blood sugar is suspected. They should be made aware that an emergency glucagon injection may not work because of depletion of the liver’s stores of stored sugar (glycogen).
Medical alert identification should be worn. Any scheduled basal insulin such as glargine, levemir or degludec (or an insulin pump basal rate) should not be interrupted. Advanced pump features such as setting a lower temp basal rate or using alarms or temporary suspend features of a continuous glucose monitor system are very helpful. Before going to bed, the blood sugar should be checked and a snack should be eaten if the blood sugar is normal to low. Finally, it is important to stay well hydrated and resume routine insulin dosing and meals the next day.