EASD: Moderate Wine Drinking Lowers Fasting Glucose in Type 2 Diabetes

September 20, 2007

AMSTERDAM -- A glass of merlot or perhaps sauvignon blanc a day may offer modest benefits for patients with type 2 diabetes, said researchers here.

AMSTERDAM, Sept. 20 -- A glass of merlot or perhaps sauvignon blanc with dinner may offer modest benefits for patients with type 2 diabetes, said researchers here.

In a small study, teetotalers with confirmed type 2 diabetes who agreed to drink a 150 mL (five ounce) glass of wine with dinner daily for three months had modest but significant reductions (P =0.015) in fasting plasma glucose compared with controls who drank non-alcoholic diet beer, reported Iris Shai, Ph.D., of Ben Gurion University in Beer-Sheva, Israel, and colleagues.

Alcohol did not, however, have any significant effects on post-meal glucose levels, Dr. Shai reported at the meeting of the European Association for the Study of Diabetes here.

"Meta-analysis of observational studies suggests that moderate alcohol is associated with a lower risk of coronary heart disease mortality among patients with type 2 diabetes," Dr. Shai said, "and this beneficial effect is greater than among non-diabetics."

She noted that several short term studies reported decreases in fasting plasma glucose associated with alcohol consumption in patients with diabetes, but others found no significant effect.

To help clarify the situation, the authors recruited 109 abstemious patients with confirmed type 2 diabetes ages 41 to 74.

The patients were randomized in a 2:1 ratio to receive 150 mL of wine - either a merlot, for those who expressed a preference for red wine, or a sauvignon blanc, for those who wanted white - or a non-alcoholic diet malt beer (0 g alcohol, 30 calories) to be taken with dinner for three months. The patients were provided standardized glasses for their assigned beverage.

All participants received individual diet and nutritional counseling, but were not pushed to lose weight. Diet and alcohol consumption were monitored in the study.

A total of 91 patients completed the study, with significantly more dropouts occurring in the control group than in the intervention group.

"Most of them were just disappointed not to be assigned to the wine arm," Dr. Shai said.

They found that among the wine drinkers, fasting plasma glucose decreased from 139.58 mg/dL + 41.0 to 118.01 + 32.5 after three months, but there was no similar change among controls (Delta = -21.55mg/dL, P=0.015 compared with the delta of controls).

Alcohol consumption did not have an effect, however, on two-hour post-prandial glucose levels (P=0.966).

Among the wine drinkers, those with higher baseline HbA1c levels had a greater reduction in fasting plasma glucose (age-adjusted correlation -0.33, P=0.045).

There were no significant hepatic effects of introducing alcohol to previous non-drinkers, as evidenced by measures of serum bilirubin, alkaline phosphatase, alanine aminotransferase (ALT), or aspartate aminotransferase (AST).

When asked about possible adverse effects, new wine drinkers reported no significant changes from baseline compared with controls, except for an improved ability to fall asleep.

Dr. Shai said that the effects of ethanol may be similar to that of metformin, which inhibits hepatic glucose production.

"We are discussing a lot what drives the beneficial effects of wine," Dr. Shai replied. "We're not sure if it's the ethanol or the other components of the red wine ? but in the future if we compared only red wine to controls, we would never know if it was the ethanol or the other components." Red wine is high in flavanols and catechines, both of which have beneficial metabolic effects, but white wine is not.