How Safe Is Alcohol for Patients With Diabetes?

Q: What are the effects of acute alcohol ingestion on diabetes mellitus?

A: Alcohol ingestion is one of the most common causes of disabling hypoglycemia in the United States. The effects of alcohol ingestion on patients with diabetes vary considerably, depending on whether they have type 1 or type 2 diabetes and on whether they are receiving insulin therapy.¹

In patients with type 1 diabetes, acute alcohol ingestion often results in severe hypoglycemia. Because alcohol does not significantly alter hepatic glucose production in most patients with type 2 diabetes,² hypoglycemia secondary to alcohol ingestion is unusual in these persons unless they are receiving insulin. However, the reaction to alcohol of patients with long-standing type 2 diabetes who are receiving replacement insulin therapy secondary to loss of -cell reserve is similar to that of patients with type 1 disease. In fact, among patients with either type of diabetes who are treated with insulin, alcohol has been implicated in up to 20% of hospital admissions for hypoglycemia.³

Effects of alcohol that contribute to hypoglycemia. The ingestion of alcohol results in metabolic by-products that reduce hepatic glucose production via gluconeogenesis. Because the glucagon response is still intact in most patients with non-insulin-dependent diabetes, glycogenolysis can temporarily help maintain circulating glucose levels in these patients even though gluconeogenesis is inhibited. However, the impaired glucagon response and loss of available glycogen stores seen in insulin-dependent diabetes limit this source of hepatic glucose as well.

In addition to inhibiting hepatic glucose production, the ingestion of alcohol has several other effects that directly impair normal hormonal counterregulatory responses to hypoglycemia. First, alcohol blocks lipolysis by inhibiting the release of free fatty acids from adipose tissue. Alcohol also reduces the amount of growth hormone that is released in the early morning hours. This has the effect of abolishing the dawn phenomenon in patients who are insulin-dependent. Finally, alcohol metabolism increases the sensitivity of the liver to insulin,⁴ thereby triggering the use of available glucose to replenish glycogen stores.

Factors that can exacerbate the effects of alcohol. Carbohydrate intake and activity level influence the risk of hypoglycemia following ingestion of alcohol. Ingestion of alcohol following a prolonged fast reduces hepatic glucose output by 23% in healthy persons.⁵ This effect is exacerbated during relative starvation or when carbohydrate intake is poor.

Factors that can impede response to signs of hypoglycemia. The effects of alcohol can impair a patient's judgment, leading him or her to ignore the early signs and symptoms of hypoglycemia and to postpone treatment. The risk of unawareness of incipient hypoglycemia is especially great in patients whose blood glucose levels are normally strictly controlled and in whom hypoglycemic incidents have been rare. Finally, alcohol tends to cause delayed hypoglycemia 10 to 16 hours following ingestion. The delayed nature of the reaction further increases the likelihood that the hypoglycemia will not be recognized and properly treated.

When these various factors converge, a hypoglycemic episode is both more likely-and more likely to be initially ignored. Consider, for example, the case of a college student with type 1 diabetes who normally has excellent glycemic control and who ingests alcohol in the evening, eats little food, and is physically active (eg, dances). Delayed hypoglycemia might occur 10 to 16 hours later.^2,6,7 Its first signs might well be missed.

Treatment of alcohol-induced hypoglycemia. Treat hypoglycemia resulting from alcohol ingestion with intravenous glucose. Glucagon administration is effective in patients with hypoglycemia only if liver glycogen is available. Because alcohol reduces hepatic glucose production, sufficient glycogen may not be available.

Prevention of alcohol-induced hypoglycemia. The following measures can reduce the risk of hypoglycemia in patients with insulin-dependent diabetes who drink:

• Limiting alcohol intake (hypoglycemia is less likely if no more than 2 drinks are consumed).

• Ingesting carbohydrates before and along with the consumption of alcohol.

• Avoiding strenuous activity while drinking.

Key Points for Your Practice

• In patients with type 1 diabetes and those with type 2 diabetes who require insulin, acute alcohol ingestion can result in severe hypoglycemia.

• Alcohol tends to cause delayed hypoglycemia 10 to 16 hours following ingestion; this increases the risk because after that much time has elapsed, hypoglycemia may not be recognized and properly treated.

• Treat hypoglycemia resulting from alcohol ingestion with intravenous glucose rather than glucagon.

References:

REFERENCES:1. Pandit, MK Burke J, Gustafson AB, et al. Drug-induced disorders of glucose tolerance. Ann Intern Med. 1993;118:529-539.
2. Plougmann S, Hejlesen O, Turner B, et al. The effect of alcohol on blood glucose in type 1 diabetes-metabolic modelling and integration in a decision support system. Int J Med Inform. 2003;70:337-344.
3. Potter J, Clarke P, Gale EA, et al. Insulin-induced hypoglycaemia in an accident and emergency department: the tip of an iceberg? Br Med J. 1982;285:1180-1182.
4. Avogaro A, Beltramello P, Gnudi L, et al. Alcohol intake impairs glucose counterregulation during acute insulin-induced hypoglycemia in IDDM patients. Diabetes. 1993;42:1626-1634.
5. Meeking DR, Cavan DA. Alcohol ingestion and glycaemic control in patients with insulin-dependent diabetes mellitus. Diab Med. 1997;14:279-283.
6. Richardson T, Weiss M, Thomas P, et al. Day after the night before: influence of evening alcohol on risk of hypoglycemia in patients with type 1 diabetes. Diabetes Care. 2005;28:1801-1802.
7. Turner BC, Jenkins E, Kerr D, et al. The effect of evening alcohol consumption on next-morning glucose control in type 1 diabetes. Diabetes Care. 2001;24:1888-1893.