Adults with type 2 diabetes who drank five ounces of red or white wine with dinner for two years had a modest decrease in cardiometabolic risk compared with a group that drank mineral water, according to a randomized trial.

After two years, high-density lipoprotein cholesterol levels significantly increased by 2.0 mg/dL in the red wine group compared with the water group, while the total cholesterol to HDL cholesterol ratio decreased by 0.27 in the red wine group compared with the water group.

Meanwhile, participants in the white wine group had significant decreases in fasting plasma glucose and homeostasis model assessment of insulin resistance score compared with the water group.

The three groups had no differences in blood pressure, adiposity, liver function, drug therapy, symptoms or quality of life, although sleep quality improved in the wine groups compared with the water group.

Lead researcher Yftach Gepner, MPH, and Rachel Golan, PhD, of Ben-Gurion University of the Negev in Israel, and colleagues published their results online in the Annals of Internal Medicine on Oct. 12.

“Differential effects on glycemic control we saw were based on ADH1B genetic variants, which indicate that ethanol may play a role in the glycemic effects of the wine intervention,” they wrote. “ADH1B variants may assist in identifying patients with [type 2 diabetes] for whom moderate wine consumption may be clinically beneficial.”

They mentioned that the American Diabetes Association recommends people with type 2 diabetes have their own preference with regards to moderate alcohol consumption, while the American Heart Association recommends type 2 diabetics speak with their physicians about alcohol use.

In this trial, called CASCADE (Cardiovascular Diabetes and Ethanol), the researchers randomized 224 adults to receive five ounces of mineral water, white wine or red wine with dinner from June 2010 to May 2012. The study was conducted at Ben-Gurion University of the Negev–Soroka Medical Center and Nuclear Research Center Negev in Israel.

The study included adults with type 2 diabetes who were between 40 and 75 years old. Participants were excluded if they drank more than one alcoholic drink per week, had a personal or family history of addiction, smoking, stroke or MI; surgery within the last three months; used more than two insulin injections per day or an insulin pump and had a triglyceride level greater than 400 mg/dL and hemoglobin A1c (HbA1c) level less than 6.4 percent or 10 percent or more. Women who were pregnant or had first-degree relatives with breast cancer were also excluded.

At baseline, the mean age was 59, the mean HbA1c level was 6.9 percent and the mean alcohol intake was approximately one drink per week. Of the participants, 69 percent were men and most received medications for diabetes, hypertension and hypercholesterolemia.

The researchers provided a five-ounce measuring glass and asked participants to drink the water or wine with dinner every day. They also asked them to follow a Mediterranean diet and had clinical dieticians conduct group sessions once per month for the first three months and every three months afterward. The dieticians did not discuss wine during the sessions.

Participants completed electronic questionnaires at baseline and at six and 24 months to assess demographics, lifestyle patterns, medications, symptoms and quality of life. The researchers assessed adherence by tracking returned bottles and having participants complete questionnaires on their alcohol intake and ranking their adherence to the assigned beverages.

The researchers mentioned a few limitations of the study, including that participants were not blinded to their group assessment and researchers used fasting insulin and glucose levels to estimate insulin resistance instead of using the hyperinsulinemic euglycemic clamp.