Effects of Drinking on the Risk for Diabetes and Its Complications

What is the problem and what is known about it so far?

Type 2 diabetes mellitus interferes with the body's ability to store energy from food. The pancreas makes insulin, a substance that helps to store energy from food. In people with type 2 diabetes, the body makes plenty of insulin but cannot use it normally. The result is high blood sugar levels, and over time, high blood sugar can lead to blindness, kidney failure, and nerve damage. Diabetes increases the rate of atherosclerosis (hardening of the arteries), a condition that can lead to heart disease. Being overweight, lack of exercise, and family history of the disease increase the likelihood of developing type 2 diabetes. Nearly 8% of U.S. adults age 20 years and older have diabetes. Many others have an increased likelihood of developing diabetes.

People should avoid activities that make it more difficult to keep the blood sugar in a healthy range or that increase the chance of developing diabetes. Many people with diabetes wonder if drinking alcohol is harmful to their diabetes or increases the complications of diabetes. People at high risk for diabetes also wonder how alcohol affects their chances of getting diabetes.

Why did the authors do this review?

The authors wanted to find out about the effects of drinking alcohol on diabetes and its complications.

How did the authors do this review?

The authors searched the medical literature to find articles about the effects of alcohol on diabetes and its complications. They found 32 studies with relevant information. Two researchers read all the studies. Only a few of the studies were of “good” quality. The authors discarded poor-quality articles. They used 32 studies with some faults but none that were very serious.

What did the authors find?

Some findings related to developing diabetes. Nondrinkers and people who drank more than 3 drinks per day had the highest risk for diabetes. People who had one to 3 drinks a day had a lower risk. Other findings applied to patients who have diabetes. Moderate drinking (one to 3 drinks per day) did not have an important effect on blood sugar levels in patients with diabetes. However, this finding may not apply to all patients because the studies were done under special test conditions that differ from normal daily life. Heart disease was less common in people with diabetes who drank moderate amounts of alcohol than in those who did not.

What are the implications of the review?

People who drink up to 3 drinks a day should know that alcohol does not increase their chances of getting diabetes. Patients with diabetes should know that moderate drinking (one to 3 drinks per day) probably does not harm their diabetes, although the evidence for this conclusion is rather weak. They should also know that moderate drinking is associated with less heart disease in people with diabetes. Despite this finding, experts feel that we do not know enough to recommend that patients who do not drink alcohol should begin to drink in moderation.