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Wine and dine with diabetes

For some, wine is a daily or weekly indulgence. As those with type 2 diabetes must pay extra attention to the blood sugar and lipid impact of what they consume, this trial puts red and white wine to the test.

Study under review: Effects of Initiating Moderate Alcohol Intake on Cardiometabolic Risk in Adults With Type 2 Diabetes: A 2-Year Randomized, Controlled Trial


Fermentation of grains, fruit juices, and honey has been used to make alcohol for thousands of years. There is evidence to suggest that alcohol consumption is linked to a reduction in cardiovascular disease risk among healthy individuals. Moderate alcohol consumption has also been linked to a reduced risk[1] of type 2 diabetes. Additionally, some evidence suggests that all alcoholic beverages have similar effects[2], whereas other research argues that wine is particularly beneficial, possibly because of its polyphenol content.

A major limitation of the aforementioned evidence favoring alcohol consumption is that the evidence comes from short-term RCTs and observational research. Furthermore, the observational research shows a J-shaped relationship, indicating that benefits only exist up to a certain point. However, recommendations from authoritative bodies like the American Diabetes Association and American Heart Association leave moderate alcohol consumption to personal preference and discussion between the physician and patient, given the lack of long-term clinical trials to support causal cardioprotective effects.

The basics of alcohol metabolism are depicted in Figure 1. It’s metabolized primarily within the liver through pathways involving alcohol dehydrogenase (ADH) and the cytochrome P450 enzymes, among others. The major pathway is ADH, which converts alcohol into acetaldehyde, a highly reactive and toxic byproduct that may contribute to tissue damage and, possibly, the addictive process. This compound is then further metabolized into acetate with aldehyde dehydrogenase (ALDH), and is safely excreted from the body.

ADH isn’t a single enzyme, but broadly refers to five classes that slightly differ in function based on location within the body and activity levels. Of these, genetic variation has been shown to occur at the ADH1B and ADH1C gene locations, and this genetic variability influences a person’s susceptibility to developing alcoholism and alcohol-related health effects. Individuals with a variant type of ADH known as ADH1B1 have 1 (denoted as “CT”) or 2 (denoted as “CC”) wild-type alleles that result in slow metabolism of alcohol, whereas the ADH1B2 genotype contains two mutants (TT) that result in a more rapid metabolism of alcohol.

Figure 1: The basics of alcohol metabolism

The study under review aimed to fill several knowledge gaps with a long-term RCT that provides stronger evidence than previous research. It evaluated the impact of consuming one glass of red or white wine, potentially identifying effects of wine polyphenols in addition to the alcohol content, on individuals with type 2 diabetes over a two-year period. The trial assessed whether genetic variations in ADH mediated any effects.

Short-term and observational evidence suggests that alcohol may confer some cardiovascular protection in healthy individuals and those with type 2 diabetes. This study sought to evaluate the long-term (two-year) impact of wine consumption in people with type 2 diabetes.

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