Insulin resistance and diabetes are not the same thing, but these medical issues are closely related. With insulin resistance, the body stops responding normally to the hormone insulin. This leads to a buildup of blood sugar. If left unchecked, insulin resistance commonly leads to type 2 diabetes (T2DM). Some people, with a condition called prediabetes, are insulin resistant but are not yet diabetic. Research suggests that alcohol has an effect on insulin resistance. This effect seems to be variable, however, depending on the amount of alcohol consumed and the pattern of drinking. A person's sex, race and body mass index also seem to influence the effect of alcohol on insulin resistance.
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Past studies suggested that moderate drinking might reduce insulin resistance and protect against T2DM. More current studies, however, call this into question. A September 2015 "Diabetes Care" article reported on pooled results from 38 studies that evaluated the relationship between alcohol intake and T2DM risk. The researchers found that overall, people who drank 1 standard alcoholic beverage daily were 18 percent less likely to develop T2DM compared to nondrinkers. However, when the researchers analyzed the results further, they found the protective effect was only experienced by certain groups of people.
Influence of Gender
In examining the results of the 2015 "Diabetes Care" study by the sex of the participants, a reduced T2DM risk associated with alcohol consumption was seen only in women. The greatest level of reduced risk was seen with moderate drinking among women, approximately 2 standard drinks per day. Female study participants who drank heavily -- approximately 5 or more drinks per day -- did not experience a reduced risk for T2DM. Among men, drinking was found to be associated with increased risk for T2DM. The researchers found increased diabetes risk among men even with light drinking, 1 standard alcoholic beverage per day or less.
Influence of Race
When researchers evaluated the pooled results of the 2015 "Diabetes Care" according to Asian vs. non-Asian heritage of the study participants, they found moderate alcohol consumption reduced T2DM risk only in non-Asian people. No risk reduction was seen among Asian study participants. As the authors of a 2008 "Asia Pacific Journal of Clinical Nutrition" review article explain, genetic differences between people of Asian vs. non-Asian heritage may account for different metabolic responses to alcohol consumption and a higher overall risk for T2DM among Asians. Additional research is needed to better understand how genetic variability among people of different races might affect the relationship among alcohol consumption, insulin resistance and T2DM risk.
Influence of BMI
The authors of the 2008 "Asia Pacific Journal of Clinical Nutrition" review article noted that BMI -- a measure of relative leanness or above normal weight -- appears to influence the effect of alcohol consumption on insulin resistance and T2DM risk among Japanese people. After reviewing the results from 7 studies, the authors concluded that moderate to heavy drinking among lean Japanese men increases the risk to T2DM. However, at least one study found that moderate drinking -- fewer than 3 drinks per day -- among heavier Japanese men was associated with a reduced risk for T2DM. Additional research is needed as not all studies have found that BMI affects the relationship between alcohol consumption and T2DM risk. A March 2005 "Diabetes Care" article that pooled results from studies examining this relationship concluded that BMI was not a significant factor.
Negative Effects of Alcohol
While the effects of light to moderate alcohol consumption on insulin resistance and T2DM risk appear variable, heavy drinking is clearly associated with an increased risk. Research suggests that drinking could increase the likelihood of T2DM development by increasing insulin resistance and impairing the body's ability to process blood sugar.
A February 2015 "World Journal of Biological Chemistry" study report noted evidence from research performed in rats to suggest that drinking alcohol could disrupt the function of the body's insulin-producing cells. When these cells aren't working properly, the risk for insulin resistance and T2DM can increase. Another animal study report published in January 2013 in "Science Translational Medicine" noted similar findings with binge drinking -- consuming 5 or more drinks within 2 hours for men, or 4 or more for women. The researchers found that rats fed alcohol in amounts that mimic binge drinking in people experienced increased insulin resistance that continued for at least 2 days.
Warnings and Precautions
While moderate alcohol consumption might have beneficial effects on insulin resistance in some people, drinking may not benefit and could potentially increase T2DM risk in others. Drinking alcohol can also cause problems for people living with diabetes. Alcohol consumption can increase the risk for low blood sugar several hours after drinking. Conversely, drinking can lead to high blood sugar in some situations. The American Diabetes Association recommends that people with prediabetes or diabetes who choose to drink do so in moderation -- no more than 1 standard drink daily for women and 2 for men. A standard drink is 12 ounces of beer, 5 ounces of wine or 1.5 ounces of distilled alcohol.
All people with diabetes, prediabetes or an increased risk for T2DM should talk with their doctor about the possible risks and benefits of drinking alcohol. A number of factors affect the relative risks of drinking alcohol, including medications, body weight and the presence of liver disease.