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| Date: 03-15-2016 | HC# 021622-540 |
Mori TA, Burke V, Zilkens RR, Hodgson JM, Beilin
LJ, Puddey IB. The effects of alcohol
on ambulatory blood pressure and other cardiovascular risk factors in type 2
diabetes: a randomized intervention. J
Hypertens. March 2016;34(3):421-428.
Type 2 diabetes is associated with several
other diseases or risk factors, including hypertension, dyslipidemia, high
levels of inflammation and oxidative stress, and cardiovascular disease, which
is the leading cause of death in patients with type 2 diabetes. Alcohol
consumption may have a positive effect on some of these conditions and a
negative effect on others, depending upon the amount and type of alcohol
consumed. Acute alcohol consumption can increase insulin sensitivity, and low to
moderate consumption can result in better glycemic control, decreased
inflammation, and improved endothelial function. Heavier alcohol consumption
can increase blood pressure, serum triglycerides, homocysteine levels, arterial
stiffness, and incidence of metabolic syndrome. In this crossover study, the
short-term effects of red wine (from Vitis
vinifera, Vitaceae) consumption on blood pressure, glycemic control, and
other cardiovascular risk factors were measured in patients with type 2
diabetes.
The study was conducted at the School of
Medicine and Pharmacology at the Royal Perth Hospital in Perth, Western
Australia, Australia, from August 2003 to February 2004. Included patients were
men and postmenopausal women between the ages of 40 and 70 who had type 2
diabetes, defined as use of hypoglycemic medication, 2 fasting plasma glucose measurements
of > 7.1 mmol/l, or a diabetic glucose tolerance test. Patients were
required to have consumed alcohol regularly for the previous year, women on
average consuming 2 to 3 Australian standard drinks per day and men, 3 to 4.
Patients were excluded if they had type 1 diabetes, a history of myocardial
infarction or stroke, recent (< 3 months) cardiovascular symptoms or major
surgery, peripheral vascular disease, blood pressure > 170/100 mm Hg, liver
or kidney disease, hemoglobin A1c levels > 8.5%, or if they had smoked
within 2 years. Patients using medications for hypertension or dyslipidemia
were not excluded. The study was divided into four 4-week phases. The first
phase was a 4-week run-in during which usual alcohol consumption was maintained.
Each patient then completed each of the remaining 3 phases, which included a
red wine phase, a dealcoholized red wine phase, and a water phase, in a
randomized, crossover design.
Female patients consumed 230 ml of red wine
(Shiraz Cabernet; donated by Orlando Wyndham Group; Rowland Flat, South Australia,
Australia), dealcoholized red wine (donated by Orlando Wyndham Group), or water
daily with the evening meal; male patients consumed 300 ml. Wine doses
contained 24 g of alcohol for women and 31 g for men. There was no washout
period between phases. At the end of each phase, blood pressure and heart rate
were measured for 24 hours with an ambulatory monitor and a 24-hour urine
sample and fasting blood sample were taken. Patients recorded their blood
glucose levels 4 times per day on Monday and Thursday of each week. Blood levels
of total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density
lipoprotein cholesterol (LDL-C), triglycerides, fibrinogen, homocysteine,
insulin, and glucose were measured; the last 2 values were used to calculate
insulin resistance. Urinary sodium excretion and sodium/creatinine ratio were
measured. Urinary 4-O-methylgallic acid was assayed as a marker of compliance
with wine consumption, and blood γ-glutamyl transpeptidase (γ-GT) as a marker
of change in alcohol consumption. Statistical analyses included use of repeated
measures mixed models (for blood pressure data) and General Linear Model
repeated measures (for biomarker measurements and weight).
Twenty-eight patients met the inclusion
criteria, and 24 patients completed the study. Patients' mean age was 59.3 ±
5.6 years, and their mean body mass index was 29.3 ± 4.8 kg/m2. Average
24-hour systolic blood pressure (SBP) at the beginning of the study was 130.1 ±
11.9 mm Hg, and diastolic blood pressure (DBP) was 77.7 ± 6.4 mm Hg. Urinary
levels of 4-O-methylgallic acid were similar following the red wine and
dealcoholized red wine phases but approximately 80% lower after the water phase;
blood levels of γ-GT were lower after the water phase than the red wine phase. Both
SBP and DBP while awake were significantly greater after the red wine phase
than the water phase (P = 0.033 and 0.008, respectively). In contrast, DBP
while sleeping was significantly lower after the dealcoholized red wine phase
than after the water phase (P = 0.016). Red wine significantly increased heart
rate relative to dealcoholized red wine and water (P < 0.01 for both). Total
cholesterol and the ratio of total cholesterol to HDL-C varied significantly
among phases (P = 0.005 and 0.037, respectively), with the lowest values after
the water phase. Urinary sodium excretion was lowest following the red wine
phase, but the difference was not significant after correction for
nonsignificantly lower creatinine levels. No other biomarkers varied among
phases.
Red wine consumption did not alter glycemic
control in patients with type 2 diabetes but was associated with increases in
serum cholesterol, cholesterol to HDL-C ratio, waking SBP and DBP, and heart
rate. Such changes are associated with increased risk of cardiovascular
disease; however, as the authors note, alcohol consumption is strongly
associated with lower risk. Other studies have shown that the effect of alcohol
consumption on blood pressure is biphasic, with a reduction in blood pressure in
the first hours after consumption followed by an increase. Varying effects of
alcohol on glycemic control and insulin sensitivity are reported; differences
in dosing and consumption patterns may be partly responsible. Doses in this
study were high. Patients' use of hypoglycemic, dyslipidemic, and hypertensive
medications may have affected outcomes. The study was limited by its small
sample size and the impossibility of blinding. Patients were required to be
fairly heavy drinkers, who may have atypical physiological responses or be less
likely to comply fully with protocols requiring abstinence.
—Cheryl McCutchan, PhD
