"Is it okay to drink just a little bit?"

This is a thought that likely crosses the mind of anyone who is concerned about their health but finds it difficult to completely quit drinking.

In particular, many people assume that as long as they avoid binge drinking, small amounts of alcohol will not pose a major health problem.

However, the story can change for those with higher-than-normal blood sugar levels.

Recently, research results have suggested that individuals with diabetes or impaired fasting glucose, which corresponds to prediabetes, face a higher risk of colorectal cancer even if they consume relatively small amounts of alcohol.

Colorectal cancer is one of the most common cancers in South Korea.

According to the National Cancer Registration Statistics released earlier this year by the Korea Central Cancer Registry, newly diagnosed colorectal cancer cases in 2023 stood at 32,610, accounting for 11.3% of all cancers and ranking third.

According to the latest issue of the international journal Journal of the National Cancer Institute (JNCI), a joint research team from Samsung Medical Center and Soongsil University analyzed the impact of blood sugar status and alcohol consumption on the risk of developing colorectal cancer among 4,475,492 adults who underwent national health examinations in 2012.

The median follow-up period was 9.3 years, during which 51,592 people were diagnosed with colorectal cancer.

Looking solely at blood sugar status, there was a difference in colorectal cancer risk.

Fasting blood sugar levels below 100 mg/dL were classified as normal, and 100 to 125 mg/dL as impaired fasting glucose.

Diabetes was defined as a fasting blood sugar level of 126 mg/dL or higher, or being prescribed therapeutic drugs at least once a year under a diabetes diagnosis code.

Compared to people with normal blood sugar, the risk of developing colorectal cancer was 11% higher for those with impaired fasting glucose and 26% higher for diabetes patients.

When alcohol consumption was added to the equation, the gap widened further.

The research team classified moderate drinking or less as less than 30g per day for men and less than 20g per day for women.

Translating this to typical drinks, 20g of alcohol corresponds to about 2 to 3 glasses of soju, and 30g to about 3 to 4 glasses.

The analysis showed that among moderate drinkers, those with impaired fasting glucose had a 23% higher risk of colorectal cancer compared to non-drinkers with normal blood sugar, while the risk for diabetes patients surged by up to 48%.

This indicates that alcohol can act as a factor further increasing the risk of colorectal cancer for people with high blood sugar.

The difference was even greater in cases of heavy drinking.

Compared to normal blood sugar non-drinkers, the risk of colorectal cancer was 17% higher in the normal blood sugar heavy drinking group, 41% higher in the impaired fasting glucose heavy drinking group, and 77% higher in the diabetes heavy drinking group.

In particular, this study observed a "synergistic effect" where drinking alcohol when having impaired fasting glucose or diabetes increased the risk of colorectal cancer beyond simply adding the effects of the two individual risk factors.

The research team suggested the overlap of oxidative stress and inflammation as one possible explanation.

Drinking alcohol can lead to the accumulation of acetaldehyde, a carcinogen produced during alcohol breakdown, and increase mucosal inflammation and oxidative stress.

High blood sugar can also elevate oxidative stress through the generation of advanced glycation end products and the activation of inflammatory signaling pathways.

It is possible that the overlapping of these two processes creates an environment vulnerable to the transformation of colon cells into cancer.

In addition, they presumed that the relative prevalence among East Asians, including Koreans, of a genetic mutation (ALDH2) that impairs the breakdown of acetaldehyde could be one of the reasons why even relatively small amounts of alcohol increase the risk of colorectal cancer.

The research team stated, "An association with an increased risk of colorectal cancer was confirmed even at moderate or lower levels of alcohol consumption, and this association was particularly prominent in individuals with impaired fasting glucose or diabetes," adding, "The more abnormalities people have in blood sugar metabolism, the more minimizing alcohol intake can help lower the risk of colorectal cancer."