Women who drink a lot of alcohol and engage in binge drinking starting in their mid-teens are more likely to have high blood sugar - a risk factor for type 2 diabetes - when they reach their early 40s.
The study that comes to this conclusion is the first to assess 27 years of alcohol consumption in men and women, starting from the age of 16, and relate it to blood glucose levels at the end of the period.
The researchers, from Umeå University in Sweden, report their findings in the journal BMC Public Health.
Having blood sugar, or glucose, that is higher than normal but not high enough for a diagnosis of diabetes is classed as prediabetes - a condition that affects around 1 in 3 people, or 86 million individuals, in the United States.
People with prediabetes are at higher risk of developing type 2 diabetes, heart disease, stroke, and other serious health problems.
Study plugs gap in research
In describing the reasons for their study, the authors explain that previous investigations have proposed that moderate drinking is linked to reduced risk for type 2 diabetes, and that women appear to benefit more than men.
However, they suggest that the pattern of drinking could be just as important as the amount in assessing the long-term relationship between alcohol intake and glucose levels.
They also point to the lack of research that tracks drinking habits from adolescence and relates them to glucose levels in the middle years.
Therefore, they decided to plug this research gap by using records on nearly 900 men and women taking part in the Northern Swedish Cohort study, which started collecting data in 1981.
The data in the Swedish records allowed the researchers to examine alcohol intake and binge drinking starting from age 16 through to age 43, and relate it to fasting blood glucose at the end of that period.
The data on alcohol consumption came from questionnaires that the participants completed at age 16, 18, 21, 30, and 43 - the age at which their blood glucose was measured.
The researchers defined binge drinking as "drinking four or more standard drinks of beer, wine, or spirits per occasion for women (five or more standard drinks for men) at least once a month."
Higher alcohol intake tied to higher glucose
First author Dr. Karina Nygren says, "Our findings show that high alcohol consumption from ages 16 to 43 is associated with higher blood glucose levels in women but not in men."
The significant link between higher blood glucose and the women's total alcohol intake and binge drinking over the 27-year period was independent of other factors known to affect blood glucose, such as body mass index (BMI), blood pressure, and smoking.
However, for men, there was no such strong independent link between blood sugar and total alcohol intake and binge drinking. In their case, the only strong link to high blood sugar was with BMI and blood pressure.
Nonetheless, despite the fact that women had this extra, independent link to high blood glucose from high alcohol intake and binge drinking, the men's blood glucose levels were found to be higher than the women's, and their alcohol intake over the 27 years from adolescence was nearly three times higher than the women's.
No biological explanations
Previous research has suggested that ethanol, the alcohol in alcoholic beverages, can interfere with the ability of cells to use insulin to help them absorb glucose for energy - a condition known as insulin resistance.
Other studies that have examined binge drinking in rats have suggested that the habit changes the body's metabolism in a way that impairs insulin.
However, while such studies may explain biologically how high alcohol intake might lead to high blood glucose, they do not explain the current study's findings about why this should be different in men and women.
The researchers point out that their study was not designed to determine whether higher alcohol consumption and binge drinking actually causes high blood glucose. It can only show that such a relationship exists, that it is independent, and that it is statistically significant.
"Because higher blood glucose is a risk factor for the development of type 2 diabetes, our data suggest that informing people about the risk of high alcohol consumption at a young age could have positive health impacts further down the line."
Dr. Karina Nygren