Alcohol, Blood Glucose and Diabetes

Chart 1. Effect of Moderate and Heavy Drinking on the Blood Glucose Levels
DRINKING PATTERN	EFFECT ON THE BLOOD GLUCOSE
	Healthy individuals	Individuals with Diabetes 1	Individuals with Diabetes 2
A SINGLE alcohol session (0.5-1 gram alcohol/kg body weight or 2-5 drinks) with a meal	No significant change in the blood glucose levels [9,12,13]	Possible slight fall of the fasting or after-meal glucose levels [4,9]	No change, or slight fall of the after-meal glucose [9]
BINGE drinking on an empty stomach	Possible hypoglycemia [9]	Possible hypoglycemia [9]	Possible hypoglycemia [9]
REGULAR MODERATE drinking (1 drink = 13 g alcohol/day) before meals	Decreased risk of diabetes 2 [3,6,7,8]	Decreased HbA1c levels [11]	Lower fasting glucose, but not after-meal glucose levels [2,14], decreased HbA1c levels [11]
HABITUAL drinking (3-4 drinks = 45 g alcohol/day) by well nourished individuals	Decreased risk of diabetes 2 [10]	Decreased HbA1c levels [11]	Decreased HbA1c levels [11]
CHRONIC HEAVY drinking (>4 drinks, that is >50 g alcohol/day by well nourished individuals	Increased risk of diabetes 2 [1]	Decreased HbA1c levels [11]	Decreased HbA1c levels [11]; increased fasting glucose and glucose after a meal [15]

Chart 1 references: ^{[1,2,3,4,6,7,8,9,10,11]}

Alcohol and Blood Glucose in Healthy People

In healthy individuals, long-term moderate drinking does not significantly affect fasting and after-meal blood glucose levels ^[6,16,17,18].

Binge drinking increases the risk of diabetes 2 in women ^[10].

In one study, in lean healthy individuals, moderate amounts of alcohol (1-3 drinks) consumed with carbohydrate meals attenuated the rise of glucose levels after meals for up to 37% ^[6].

Blood Glucose in Chronic Alcoholics

It is estimated that 45-70% of chronic alcoholics with alcoholic liver disease (hepatitis or cirrhosis) have glucose intolerance or diabetes type 2 ^[1]. Hyperglycemia is also common in chronic alcoholics without liver disease ^[19].

Alcohol Effect on Blood Glucose in Diabetes Type 1

According to one large 2006 study, alcohol drinking (mild, moderate or heavy) decreases HbA1c (hemoglobin with attached glucose) levels in individuals with diabetes 1 ^[11]. HbA1c reveals average glucose levels over the last 2-3 months. Lower HbA1c means better control of blood glucose (less hyperglycemia) during 2-3 months preceding testing ^[20].

Individuals with diabetes type 1 who drink moderately amounts of alcohol in the evening may have hypoglycemia after the breakfast next morning ^[21].

Diabetics type 1 who binge drink on an empty stomach for several days may develop diabetic ketoacidosis with nausea, vomiting, fruity smell of breath, frequent urination, thirst, confusion, coma or can die ^[22].

Alcohol Effect on Blood Glucose in Diabetes Type 2

• Moderate drinking decreases insulin resistance and the risk of diabetes type 2 ^[3,6,7,8].
• Alcohol drinking (mild, moderate or heavy) can decrease HbA1c levels in individuals with diabetes 2 ^[11].
• In one study, in individuals with diabetes type 2 who previously abstained from alcohol and were then drinking 150 mL of wine (13 g alcohol) with dinner each day for 3 months, a drop of fasting glucose from 140 to 118 in average, but no change in glucose levels after a meal, was observed ^[2].
• Alcohol consumed together with certain oral anti-diabetic drugs (chlorpropamide, glibenclamide, glipizide, glyburide, tolbutamide) may cause hypoglycemia, especially in fasting individuals ^[4,5,17,23].
• Heavy drinkers are at increased risk of developing diabetes type 2, probably due to the damage of the pancreas and decreased insulin sensitivity ^[1].

Should Diabetics Drink Alcohol?

Moderate drinking may be beneficial for both diabetics type 1 and type 2, since it decreases HbA1c levels and thus the risk of long-term complications ^[11]. Excessive drinking may be harmful for diabetics, because it increases the risk of obesity, elevated blood triglycerides, high blood pressure, peripheral neuropathy, hypoglycemia or hyperglycemia, impotence and diabetic retinopathy ^[9].

Alcohol-Related Hypoglycemia

Heavy drinking without eating for more than 24 hours may, especially in chronic alcoholics, result in severe hypoglycemia (low blood glucose level) within 6 to 36 hours after drinking. Mechanism: fasting depletes the body’s stores of glycogen – a molecule from which glucose is released into the blood, and alcohol inhibits formation of new glucose in the liver ^{[9,24,25,26,27,28]}. Severe alcohol-related hypoglycemia seems to be rare ^[28].

Combining alcohol and carbohydrates (sweet liqueurs, vodka and soft drinks, rum and cola, gin tonic, or alcohol with carbohydrate snacks) may, within 1-3 hours of consumption, trigger reactive hypoglycemia with hunger, shakiness, dizziness and weakness ^[29,30]. Mechanism: carbohydrates stimulate insulin secretion and alcohol enhances its effect what results in excessive drop of blood glucose ^[29,31]. Risk factors for reactive hypoglycemia include obesity, anxiety, irregular meals, diabetes 2, adrenal insufficiency, hypopituitarism ^[32,33].

Glycemic Index of Alcohol Beverages

An estimation of glycemic index of some alcoholic beverages ^[6]:

• Beer GI = 57
• White wine GI = 7
• Gin GI = 10
• Liqueurs with high sugar content may have high GI.