There is evidence that
type 2 diabetes
is less prevalent among moderate drinkers, yet the risk-benefit balance
is controversial for such patients, due to a lack of long-term
randomized studies.
Researchers from Ben-Gurion University of the Negev-Soroka Medical
Center and Nuclear Research Center Negev, Israel, wondered if both red
and white wine might improve glucose control, depending on alcohol
metabolism and genetic profiling.
Previous research has suggested that ethanol (alcohol) is the key,
meaning that alcoholic drinks other than red wine could be equally
beneficial; others claim that red wine has particularly advantageous
properties.
People with
diabetes have a higher risk of developing cardiovascular disease, as well as lower levels of "good" HDL
cholesterol. High levels of HDL cholesterol can reduce the risk for
heart disease and
stroke, as it absorbs cholesterol and carries it back to the liver, where it is flushed from the body.
Should patients with type 2 diabetes be recommended to take up moderate
alcohol consumption? The American Diabetes Association (ADA) leave the
decision to the individual; the American Heart Association (AHA)
recommend discussing alcohol with a physician.
The researchers wanted to find out what the cardiometabolic effects
would be when patients with type 2 diabetes took up drinking moderate
amounts of alcohol; they also wanted to assess whether the type of wine
would matter.
They hypothesized that initiating moderate wine consumption would lower
cardiometabolic risk, mainly because of the ethanol component. They
predicted similar effects of red and white wine. Because of genetic
variability in alcohol metabolism, they predicted that the effects of
wine would vary according to ADH1B genotype.
The 224 participants were 40-75-year-old alcohol-abstaining men and women with well-controlled type 2 diabetes.
Among those excluded were: people already taking more than one alcoholic drink per week, anyone with a history of
addiction and patients using two or more
insulin injections a day.
Measurements taken at baseline included genetic markers,
blood pressure, liver biomarkers, medication use and symptoms, and quality of life.
From June 2010 to May 2012, participants were randomly assigned to 150
mL of mineral water, white wine or red wine with dinner. Wines and
mineral water were provided. All groups followed a
Mediterranean diet without caloric restriction. At intervals, blood samples were taken, questionnaires completed and group sessions attended.
Lipid and glycemic control profiles were primarily measured. Secondary
outcomes included triglyceride levels, blood pressure, waist
circumference, genetic interaction, medication use, liver function tests
and quality-of-life indicators.
After 2 years, no material differences were identified across the groups
in blood pressure, adiposity, liver function, drug therapy, symptoms or
quality of life, except that sleep quality improved in both wine groups
compared with the water group.
However, patients who drank wine showed decreased
cardiometabolic risks compared with those drinking mineral water. The
red wine drinkers experienced the most significant changes in lipid
variables.
The researchers unexpectedly found that while the alcohol itself appears
to aid glycemic control, red wine has a stronger effect on lipid levels
and overall variables of the metabolic syndrome, suggesting that its
non-alcoholic constituents also play a role.
The red wine had seven times higher levels of total phenols than the
white wine. Whether the phenolic compounds increase the
cardioprotectiveness is still debated. The team calls for differences
between red and white wine to be further studied, with focus on the
varied biodeliverability of the compounds.
The team found that genetic differences affected glycemic control and
therefore suggest that genetic information could assist in identifying
which patients with type 2 diabetes would benefit from moderate wine
consumption.
Limitations include the participants not being blinded to treatment
allocation, but the long-term nature of the study is a strength.
The authors caution that the benefits of drinking wine should be weighed
against potential risks when translated into clinical practice.