It’s the kind of study that produces headlines social media loves: “Regular alcohol consumption could cut diabetes risk,” “Want to keep diabetes at bay? Drinking alcohol might just help,” and “You now have a good reason to drink six beers next week.”
As one person gleefully quipped on Twitter: “I’ll drink to that one!”
But do those headlines accurately reflect the study’s findings, which were published last week by a team of Danish researchers in Diabetologia (the journal of the European Association for the Study of Diabetes)?
No. For the study was an observational one, which means it cannot conclusively determine whether alcohol offers any protection against diabetes. In fact, the study’s limitations (which I’ll get to in a minute) are significant. So, although the findings are interesting, no one should be using alcohol as a liquid talisman against diabetes.
As one expert points out, “Even if an association does exist, there are far healthier ways to reduce your diabetes risk, such as achieving or maintaining a healthy weight.”
Here’s how the study was done: Researchers at the National Institute of Public Health of the University of Southern Denmark analyzed data from 70,551 Danish adults who participated in their country’s Health Examination Survey (DAHNES) during 2007-2008. For the survey, the participants filled out a lengthy questionnaire that contained questions about health and lifestyle, including their weekly alcohol consumption.
To be part of the current study, the survey respondents could not have been diagnosed with diabetes before they filled out the questionnaire, nor could they have been pregnant within the previous six months. (Women are advised not to drink alcohol during pregnancy.)
The participants were followed until 2012. During that period, 859 men and 887 women developed diabetes. The researchers then compared the average amount of alcohol the people who developed diabetes said they drank weekly (when they filled out the questionnaire in 2007-2008) with the average weekly amount reported by the people who didn’t develop the disease.
What the data revealed
The study found that the risk of diabetes was lowest in men who consumed a weekly average of 14 drinks of alcohol and in women who consumed a weekly average of nine. Specifically, men who had 14 drinks per week were 43 percent less likely to develop diabetes than men who did not drink at all, and women who consumed nine drinks per week were 58 percent less likely to develop the disease than women who were abstainers.
Those findings held even after adjusting for such confounding factors as age, gender, body mass index, education, diet, high blood pressure and family history of diabetes.
A deeper dig into the data revealed further associations related to specific alcoholic beverages: Men who drank one to six glasses of beer per week had a 23 percent lower risk of diabetes than those who drank less than one per week. Beer had no such effect on women, apparently. But women who downed seven or more drinks of spirits (such as gin) per week had an 83 percent increased risk of diabetes compared to those who consumed less than one drink of spirits per week.
“Our findings suggest that alcohol drinking frequency is associated with the risk of diabetes and that consumption of alcohol over 3-4 weekdays is associated with the lowest risks of diabetes, even after taking average weekly alcohol consumption into account,” the study’s authors conclude.
Don’t uncork the wine bottle yet
People were only asked about their drinking habits and other risk factors at a single time point. The study doesn’t tell us whether those habits changed over the period in which people were monitored for diabetes. Most studies related to alcohol consumption also run the risk that people are not always completely accurate when describing what and how much they drink.
The way diabetes cases were recorded for the study did not distinguish between type 1 and type 2 diabetes, even though these conditions have different causes and treatments.
The study only followed people up for an average of just under five years, whereas a condition like diabetes may develop due to risk factors experienced over a longer period.
The information collected on diet may have been too simplistic to properly allow an understanding of how nutrition may also affect the diabetes risk of the people in the study.
Although the researchers excluded people from the study if they already had a diagnosis of diabetes at baseline, they didn’t exclude people if they had other chronic health conditions, some of which may contribute to diabetes risk. The only other condition that was considered in the analysis was high blood pressure.
Those are the kinds of limitations that make observational studies inconclusive, at best.
‘It is not proof’
“Overall, it is unclear whether the link between moderate alcohol drink and diabetes is real,” the NHS reviewer emphasizes. “It is not proof that starting to drink more, especially for those who do not currently drink, is useful in preventing diabetes. There are other risks, such as liver damage, to consider when drinking frequent or large volumes of alcohol above recommended limits.”
“If you are concerned that you might be at risk of developing diabetes, speak to your GP about the ways that lifestyle change can reduce your risk,” the reviewer adds.
FMI: The full Danish study is available online.