A glass of red wine every night may help people with type 2 diabetes manage their cholesterol and cardiac health, according to new findings from a two-year randomized controlled trial led by Israeli researchers.

People with diabetes are more susceptible to developing cardiovascular diseases than the general population and have lower levels of “good” cholesterol. The antioxidant resveratrol in red wine is believed beneficial for heart health; however, doctors have been hesitant to recommend moderate alcohol consumption – especially for people with diabetes — because until now there has been no long-term, randomized controlled trial proving the effects.

Funded by a grant from the European Foundation for the Study of Diabetes, this groundbreaking study assessed the effects and safety of moderate alcohol consumption in diabetics, and whether the type of wine matters.

The two-year CArdiovaSCulAr Diabetes and Ethanol (CASCADE) trial was performed at Ben-Gurion University of the Negev (BGU), Soroka Medical Center and the Nuclear Research Center Negev on 224 diabetes patients aged 45 to 75, whose disease was well controlled and who did not regularly drink alcohol. They were randomly assigned to 150 mL of mineral water, white wine or red wine with dinner for two years, following an unrestricted Mediterranean diet.

Cap: BGU Prof. Iris Shai was the lead investigator. Photo by Dani Machlis/BGU

The results were recently published in the Annals of Internal Medicine by researchers from BGU, Hadassah Hebrew University Medical Center in Jerusalem, Harvard University’s School of Public Health, the University of Leipzig and Karolinska Institute in Sweden.

“Red wine was found to be superior in improving overall metabolic profiles, mainly by modestly improving the lipid profile, by increasing good (HDL) cholesterol and apolipoprotein A1 (one of the major constituents of HDL cholesterol), while decreasing the ratio between total cholesterol and HDL cholesterol,” the scientists explained.

They concluded that “initiating moderate wine intake, especially red wine, among well-controlled diabetics, as part of a healthy diet, is apparently safe, and modestly decreases cardio-metabolic risk. The differential genetic effects that were found may assist in identifying diabetic patients in whom moderate wine consumption may induce greater clinical benefit.”

Better sleep quality

In addition to the main finding, the CASCADE researchers also discovered that both red and white wine can improve sugar control, depending on the individual’s alcohol metabolism and genetic profile.

Only the slow alcohol-metabolizers achieved an improvement in blood sugar control, while fast alcohol-metabolizers (with much faster blood alcohol clearance) did not benefit from the glucose control effect of the ethanol in the wine. Approximately one in five participants was found to be a fast alcohol-metabolizer.

Neither red nor white wine had any effect on blood pressure, liver function tests, adiposity, or adverse events/symptoms. However, sleep quality was significantly improved in both wine groups, compared with the water control group. All comparisons were adjusted for changes in clinical, medical and drug therapy parameters among patients during the years of the study.

“The differences found between red and white wine were opposed to our original hypothesis that the beneficial effects of wine are mediated predominantly by the alcohol,” said BGU Prof. Iris Shai, principal investigator of the CASCADE trial and a member of the Department of Public Health in the Faculty of Health Sciences. “The genetic interactions suggest that ethanol plays an important role in glucose metabolism, while red wine’s effects additionally involve non-alcoholic constituents.”

She added that “any clinical implication of the CASCADE findings should be taken with caution with careful medical follow-up.”