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October 28, 2015 – According to a small prospective and randomized clinical study, just published online in the Annals of Internal Medicine, a regularly taken glass of wine with dinner may improve lipid and glycemic control profiles in patients with type 2 diabetes mellitus.
Findings from the Cardiovascular Diabetes and Ethanol study (CASCADE), which included 224 patients from two centers in Israel with controlled diabetes, showed that those who consumed 150 mL/day of red wine plus a Mediterranean diet had significantly higher levels of HDL cholesterol and apolipoprotein a1 after 2 years compared with those who drank equal amounts of mineral water plus the healthy diet (the primary outcomes). In addition, the group randomized to white wine intake had significantly decreased fasting plasma glucose levels vs the mineral-water group. Both wine groups also had significantly improved triglyceride levels. Of course, long-term, large-scale multicenter trials would now be needed to follow morbidity and mortality incidence rates in this patient group, in order to still confirm a hightened overall benefit of moderatel alcohol consupmtions over risks associated. For now, however, the results suggest modest beneficial effects of initiating moderate wine consumption, and, perhaps, red wine in particular, for this patient group.
All participants underwent several tests, including continuous monitoring of changes in blood pressure (BP), heart rate, and blood glucose levels, and follow-up for the dynamic of atherosclerosis and fat by ultrasound and MRI tests. Most importantly however, genetic analysis of alcohol dehydrogenase [ADH] was performed on all study participants, because ADH is know to be polymorphic in the population. This is particularly important since ADH catalizes the first step in the metabolism of alcohol (i.e., ethanol) to acetaldehyde, which is then further metabolized to acetic acid by aldehyde dehydrogenase (ALDH). In humans, there exist several form of ADH, among them ADH1A, ADH1B, ADH1C, ADH4, and ADH5, to mention a few. Genetic variation in the ADH1B gene leads to a subgroup of individuals (carriers of the ADH1B*1 allelic variant, the so-called slow alcohol metabolizers) who metabolize alcohol muach more slowly than the group of individuals who are carriers of the ADH1B*2 allelic variant (so-called extensive alcohol metabolizers).
In the present study, at the end of 2 years, the red-wine group significantly increased their HDL-C levels by 0.05 mmol/L (2.0 mg/dL) (P<0.001) vs the water group and increased their apolipoprotein a1 level by 0.03 g/L (P=0.05). The red-wine group also decreased total cholesterol/HDL-C ratio by 0.27 (P=0.04). While there were no significant differences in lipid changes between the white-wine and water groups, the white-wine group did significantly decrease their fasting plasma glucose level by 1.0 mmol/L vs the water group (P=0.004)—a result that was not found in the red-wine group. Very interestingly, the carriers of the ADH1B*1 allelic variant (slow alcohol metabolizers) in the combined wine groups had significant improvements in glycemic control when compared to those who carried ADH1B*2 allelic variant (fast alcohol metabolizers). This also included lower fasting plasma glucose (P=0.01) and HbA1c levels (P=0.02).
This genetic interaction may suggest that ethanol plays an important and perhaps beneficiary role in some type 2 diabetes patiens, when they belong to the poor alcohol metabolizer subgroup, i.e. are carriers of the ADH1B*1 allelic variant of ADH. However, much bigger clinical studies will be necessary to confirm or disprove such beneficiary effects in the long term and measuring hard clinical endpoint for the disease such as mortality and others.